The document discusses the determination of lattice energy of ionic compounds using the Born-Haber cycle. It explains that the lattice energy of sodium chloride can be determined experimentally by considering its formation through two different methods. Method 1 is the direct combination of solid sodium and gaseous chlorine to form solid sodium chloride. Method 2 involves 5 steps including sublimation, dissociation, ionization, and combining to form ions and the ionic solid. Using Hess's law, the lattice energy is calculated by equating the enthalpy change between the two methods. For sodium chloride, the calculated lattice energy is -773.95 kJ/mol.
The document summarizes Valence Shell Electron Pair Repulsion (VSEPR) Theory. [1] VSEPR Theory predicts molecular geometry based on electron pair repulsion around a central atom. [2] The theory states that electron pairs around an atom will position themselves as far apart as possible to minimize repulsion. [3] Molecular geometry can be determined by counting the number of electron pairs and their arrangement around the central atom.
The document summarizes key information about the periodic table of elements, including its organization of elements according to atomic number and properties. Elements are grouped into families with similar properties, and the periodic table can be used to predict chemical reactions and properties of elements. Different areas of the periodic table are described, including alkali metals, transition metals, noble gases, and more.
This document discusses the four main types of chemical bonds: ionic bonds, covalent bonds, hydrogen bonds, and metallic bonds. Ionic bonds involve the transfer of electrons between atoms. Covalent bonds involve the sharing of electrons between two atoms. Hydrogen bonds are electrostatic attractions between hydrogen atoms covalently bonded to electronegative atoms and another electronegative atom. Metallic bonds are electrostatic attractions between positively charged metal ions and delocalized electrons in metals. Examples of each type of bond are provided.
The periodic table organizes the chemical elements in an orderly fashion according to their atomic number and properties. Dmitri Mendeleev created one of the first periodic tables in 1869 by arranging the elements in order of increasing atomic mass, which allowed for the prediction of undiscovered elements. The modern periodic table arranges elements by atomic number and places them into rows called periods and columns called groups based on their chemical and physical properties. Elements within the same group have similar properties including their valence electrons and the types of ions they form.
CHEMICAL REACTION
CHEMICAL EQUATION
CHEMICAL FORMULA
BALANCING
TYPES OF CHEMICAL REACTION
COLLISION THEORY
FACTORS AFFECTING THE RATE OF CHEMICAL REACTION
1. Atoms are the basic building blocks of matter and consist of a small, dense nucleus surrounded by electrons.
2. Rutherford's gold foil experiment in 1911 showed that the atom has a small, dense nucleus containing positively charged protons and uncharged neutrons.
3. Niels Bohr proposed his model of the atom in 1913 in which electrons orbit the nucleus in fixed shells at specific energy levels, explaining atomic spectra.
In the late 18th century, French chemist Antoine Lavoisier recognized the importance of accurate measurements in chemistry. He extensively studied combustion and discovered it involved reaction with oxygen. He also established the law of conservation of mass, which states that mass is neither created nor destroyed in chemical reactions, though atoms may be rearranged. A chemical equation balances the reactants and products to show equal numbers of each type of atom.
The attractive force which holds various constituents (atom, ions, etc.) together and stabilizes them by the overall loss of energy is known as chemical bonding. Therefore, it can be understood that chemical compounds are reliant on the strength of the chemical bonds between its constituents; The stronger the bonding between the constituents, the more stable the resulting compound would be.
Chemical bonds form when atoms attract each other and bind together. There are three main types of bonds: ionic bonds form when a metal transfers electrons to a non-metal, metallic bonds involve delocalized electrons that move freely between metal atoms, and covalent bonds occur when two non-metals share pairs of electrons. Ionic bonds are strong but brittle, metallic bonds allow metals to conduct heat and electricity, and covalent bonds can be single, double or triple depending on how many electron pairs are shared.
Atomic number, Mass number, Relative atomic mass and Atomic mass unitQazi GHAFOOR
The document discusses atomic number, mass number, and relative atomic mass. It states that the atomic number of an element equals the number of protons in its nucleus. The mass number is the sum of protons and neutrons. An example problem finds an atom has 92 protons and 146 neutrons from a given mass number of 238 and atomic number of 92. Relative atomic mass is the average mass of an atom's isotope compared to carbon-12, measured in atomic mass units.
This document outlines the key concepts and objectives for a unit on atoms, molecules, and ions. It will cover early atomic theories like Dalton's atomic theory, discoveries leading to the nuclear model of the atom including cathode rays and Rutherford's gold foil experiment. Students will learn about atomic structure including atomic and mass numbers. The periodic table is introduced along with chemical bonds like ionic and covalent bonds. The document also outlines naming ionic and molecular compounds as well as writing chemical formulas.
The document summarizes the key differences between ionic and covalent bonding. Ionic bonds form when a metal transfers electrons to a nonmetal, creating oppositely charged ions. Covalent bonds form when nonmetals share electrons to obtain a full outer shell. Ionic compounds have high melting points, are brittle solids, and dissolve well in water, while covalent compounds have lower melting points, are soft and pliable, and are generally insoluble in water.
The electronegativity of an element is a measure of how strongly it attracts electrons in a covalent bond. Electronegativity increases left to right and top to bottom in a period, and metals have the lowest values while nonmetals have the highest. The difference in electronegativity between two bonded atoms indicates bond type - ionic bonds form when difference is >1.7, covalent bonds form when difference is <1.7, and polar covalent bonds form for differences in between. Electronegativity values can be used to predict and investigate bond types.
1) Erwin Schrodinger developed quantum mechanics and formulated the Schrodinger equation in 1926, which treats electrons as waves rather than particles.
2) The Schrodinger equation led to the discovery of quantum numbers that describe electron behavior and allowed for a more accurate model of atomic structure.
3) There are four quantum numbers - the principal quantum number (n) describes the electron shell or energy level, the azimuthal quantum number (l) describes the subshell shape, the magnetic quantum number (m) describes spatial orientation, and the spin quantum number (s) describes electron spin.
This power point work describe about polar and nonn polar compounds and how to find it very easily and it also explain dipole moment and its calculation...this includes some workout problems
This ppt was made for our stupid projects..... The main purpose behind uploading this ppt is that no one should suffer like us and waste their time behind these stupid things... concentrate on your studies..
The document discusses Lewis structures and the rules for drawing them. It explains that Lewis structures show how atoms bond via shared electron pairs to achieve stable noble gas configurations. It provides a 4-step process for drawing Lewis structures, covering counting electrons, identifying the central atom, adding lone pairs to complete octets, and checking that all electrons are accounted for. Exceptions to the octet rule and drawing structures for ions are also covered.
This document discusses molecular bonding, energy states of molecules, bonding in solids, and electrical properties of materials. It begins by explaining different types of molecular bonding mechanisms including ionic, covalent, van der Waals, and hydrogen bonding. It then discusses the energy states and spectra of molecules, including rotational, vibrational, and electronic transitions. The document next summarizes bonding in ionic solids, covalent solids, and metallic solids. It concludes by covering electrical conduction in metals, insulators, and semiconductors, as well as properties and applications of superconductivity.
Lattice energy refers to the energy released when separate ions in the gas phase form an ionic crystal lattice. It can be calculated theoretically using the Born-Landé equation or experimentally using the Born-Haber cycle. The Born-Landé equation considers the electrostatic attraction and repulsive forces between ions, while the Born-Haber cycle uses standard enthalpy data and Hess's law. Lattice energy depends on factors like ion charge and size - higher charge or smaller ions lead to stronger electrostatic forces and higher lattice energy. Lattice energy is an important concept for understanding the properties and stability of ionic compounds.
The document appears to be describing the magnetic properties of inorganic complexes. It discusses how ligand field theory can be used to predict whether a complex will be paramagnetic or diamagnetic based on whether it forms a low-spin or high-spin configuration. Low-spin complexes tend to be diamagnetic due to having more paired electrons, while high-spin complexes are often paramagnetic since they have more unpaired electrons. The magnitude of the crystal field splitting parameter Δ depends on factors like the metal ion, its oxidation state, and the identity and geometry of the ligands.
Assignment chemical bonding_jh_sir-4163NEETRICKSJEE
This document contains information about chemical bonding. It begins with an introduction to chemical bonds, including the causes of chemical combination and classification of different bond types. It then discusses ionic bonds in depth, including how they form through electron transfer, representation of ionic compound formulas, and factors that affect ionic bond strength. The document also covers properties of ionic compounds such as physical state, isomorphism, conductivity, solubility, and polarization.
Bonding in coordination complexes (Part 1)Chris Sonntag
This document provides an overview of bonding models for transition metal compounds. It discusses valence bond theory and how ligands donate electrons to empty metal orbitals to form bonds. Crystal field theory and ligand field theory are introduced to explain how the electronic structure of transition metals is affected by ligands in their coordination sphere. The ligands create a crystal field that splits the degenerate d-orbitals of the metal into different energy levels. The size of this splitting depends on factors like the metal ion and type of ligands. Spectroscopic properties of complexes, such as color, are determined by the energy gap between these split d-orbital levels.
Coordination Chemistry, Fundamental Concepts and TheoriesImtiaz Alam
This document provides an overview of coordination chemistry concepts including:
- Werner's coordination theory which proposed that metals exhibit primary and secondary valences.
- Blomstrand-Jorgensen chain theory which suggested cobalt(III) forms complexes with only three bonds.
- Nomenclature rules for naming coordination compounds based on ligands and metal oxidation state.
- Crystal field theory which explains color and magnetic properties of complexes based on ligand effects on d orbital splitting.
- The distinction between labile complexes with rapidly substituting ligands versus inert complexes.
This document discusses chemical bonding, including ionic bonds, covalent bonds, and molecular orbital theory. It covers the factors that influence ionic bond formation, such as ionization energy and lattice energy. Born-Haber cycles are used to calculate the lattice energy of ionic compounds like NaCl. The document also discusses polar covalent bonds and how electronegativity differences between atoms determine bond polarity. Hybridization of atomic orbitals and VSEPR theory are introduced.
Crystal field theory was proposed in the 1950s to describe the bonding in ionic crystals and metal complexes. It uses an electrostatic model to explain how ligands interact with the d-orbitals of a central metal ion. This interaction splits the degeneracy of the d-orbitals into lower-energy orbitals (t2g) and higher-energy orbitals (eg). The crystal field splitting energy is determined by factors like the ligand type, metal oxidation state, and complex geometry. Crystal field theory can be used to determine properties of complexes such as color, magnetism, and spinel structures. It provides explanations for phenomena like Jahn-Teller distortions but has limitations and cannot fully describe covalent bonding.
1) The document discusses various topics relating to atomic structure and interatomic bonding, including electronic structure, ionic bonding, covalent bonding, and metallic bonding.
2) It describes the different types of bonds - ionic formed between ions with different electronegativities, covalent formed by shared electrons between similar atoms, and metallic formed by delocalized electrons in metals.
3) The properties inferred from different types of bonding are discussed, such as higher melting temperatures for stronger bonds with larger bond energies, and larger coefficients of thermal expansion for weaker bonds.
This document discusses the periodic table and periodic trends among the elements. It begins by outlining the ground state electron configurations of elements. It then classifies the elements and discusses how atomic and ionic radii vary periodically. The document also examines how other properties like ionization energy and electron affinity change across the periodic table. Specific trends in reactivity are described for representative main group elements in Groups 1A through 8A. In summary, the key periodic trends and relationships among atomic and physical properties of the elements are outlined.
A chemical bond is a lasting attraction between atoms, ions or molecules that enables the formation of chemical compounds. The bond may result from the electrostatic force of attraction between oppositely charged ions as in ionic bonds or through the sharing of electrons as in covalent bond
The document discusses Crystal Field Theory, which explains the bonding in transition metal complexes. It describes how the electrostatic interaction between ligand electrons and metal d-orbitals results in a splitting of the d-orbital energies. In an octahedral field, the t2g orbitals are stabilized more than the eg orbitals. Crystal Field Theory can explain properties like electronic spectra, magnetic moments, and color of complexes. The magnitude of splitting depends on factors like the metal ion, its charge, the ligands, and can be represented by the crystal field splitting energy Δo.
This document discusses different types of chemical bonds including ionic bonds, covalent bonds, and polar covalent bonds. It explains how ionic bonds form between a metal and nonmetal when electrons are transferred, covalent bonds form through shared electron pairs, and polar covalent bonds result from unequal electron sharing. The document also covers bond energies, dipole moments, electronegativity, and Lewis structures.
This document discusses complexation interactions and coordination complexes. It defines complex compounds as molecules where most bonds can be described by classical theories of valency but some bonds are anomalous. Complexation interactions include van der Waals forces, dipolar forces, electrostatic forces, hydrogen bonding, charge transfer, and hydrophobic interactions. Coordination complexes result from Lewis acid-base reactions between donor and acceptor molecules, consisting of a central metal ion surrounded by ligands. Examples of complexes and their electronic configurations are provided to illustrate how hybridization predicts complex geometry.
1) The document discusses the history and modern structure of the atomic model, including the discovery of subatomic particles like protons, neutrons, and electrons. It describes the structure of the atom including the nucleus and electron cloud.
2) Quantum numbers are introduced to describe the allowed energy states of electrons. Electron configuration is used to write out the arrangement of electrons in atoms and relates to an element's position in the periodic table.
3) Different types of chemical bonds are described including ionic bonds formed by electron transfer, covalent bonds formed by electron sharing, and metallic bonds formed by delocalized electrons in metal crystals. Secondary bonds like hydrogen bonds are also introduced.
1) The document discusses atomic structure and bonding, covering the history of atomic theory from Dalton to Chadwick. It describes the structure of atoms including protons, neutrons and electrons.
2) Atomic number and mass are defined, and electron configuration is explained using quantum numbers. Different types of chemical bonds are covered - ionic formed by electron transfer, covalent by electron sharing, and metallic by delocalized electrons.
3) Secondary bonds such as hydrogen and van der Waals bonds are also summarized. The periodic table is shown organizing elements by electron configuration. Different classes of elements - metals, nonmetals and metalloids - are defined by their bonding properties.
(1) The document discusses doping of semiconductors and transition metal oxides, including n-type and p-type doping of silicon. It also covers band structure diagrams and density of states plots.
(2) Preparation methods for metal oxides include molecular synthesis and solid state synthesis. Modification of solids can occur through ion exchange or intercalation. Lithium ion batteries operate through lithium intercalation into graphite.
(3) Characterization techniques covered are XRD for crystal structure analysis and electron microscopy. Magnetic properties depend on temperature; ferromagnets become paramagnetic above the Curie temperature. Spinels can exhibit ferrimagnetism from opposing sublattice
This document provides an overview of 12 units of chemistry content including atomic structure, chemical calculations, states of matter, energetics, periodic table blocks, and organic chemistry topics. It summarizes key concepts such as atomic properties, types of rays, radioactive decay, the gold foil experiment, atomic models including the Bohr model, quantum numbers, electron configuration, chemical bonding theories including ionic and covalent bonding, and Lewis structures. Diagrams are provided to illustrate electron configurations and molecular shapes determined by VSEPR theory.
(T.L.E.) Agriculture: Essentials of GardeningMJDuyan
(𝐓𝐋𝐄 𝟏𝟎𝟎) (𝐋𝐞𝐬𝐬𝐨𝐧 𝟏.𝟎)-𝐅𝐢𝐧𝐚𝐥𝐬
Lesson Outcome:
-Students will understand the basics of gardening, including the importance of soil, water, and sunlight for plant growth. They will learn to identify and use essential gardening tools, plant seeds, and seedlings properly, and manage common garden pests using eco-friendly methods.
Credit limit improvement system in odoo 17Celine George
In Odoo 17, confirmed and uninvoiced sales orders are now factored into a partner's total receivables. As a result, the credit limit warning system now considers this updated calculation, leading to more accurate and effective credit management.
Integrated Marketing Communications (IMC)- Concept, Features, Elements, Role of advertising in IMC
Advertising: Concept, Features, Evolution of Advertising, Active Participants, Benefits of advertising to Business firms and consumers.
Classification of advertising: Geographic, Media, Target audience and Functions.
Is Email Marketing Really Effective In 2024?Rakesh Jalan
Slide 1
Is Email Marketing Really Effective in 2024?
Yes, Email Marketing is still a great method for direct marketing.
Slide 2
In this article we will cover:
- What is Email Marketing?
- Pros and cons of Email Marketing.
- Tools available for Email Marketing.
- Ways to make Email Marketing effective.
Slide 3
What Is Email Marketing?
Using email to contact customers is called Email Marketing. It's a quiet and effective communication method. Mastering it can significantly boost business. In digital marketing, two long-term assets are your website and your email list. Social media apps may change, but your website and email list remain constant.
Slide 4
Types of Email Marketing:
1. Welcome Emails
2. Information Emails
3. Transactional Emails
4. Newsletter Emails
5. Lead Nurturing Emails
6. Sponsorship Emails
7. Sales Letter Emails
8. Re-Engagement Emails
9. Brand Story Emails
10. Review Request Emails
Slide 5
Advantages Of Email Marketing
1. Cost-Effective: Cheaper than other methods.
2. Easy: Simple to learn and use.
3. Targeted Audience: Reach your exact audience.
4. Detailed Messages: Convey clear, detailed messages.
5. Non-Disturbing: Less intrusive than social media.
6. Non-Irritating: Customers are less likely to get annoyed.
7. Long Format: Use detailed text, photos, and videos.
8. Easy to Unsubscribe: Customers can easily opt out.
9. Easy Tracking: Track delivery, open rates, and clicks.
10. Professional: Seen as more professional; customers read carefully.
Slide 6
Disadvantages Of Email Marketing:
1. Irrelevant Emails: Costs can rise with irrelevant emails.
2. Poor Content: Boring emails can lead to disengagement.
3. Easy Unsubscribe: Customers can easily leave your list.
Slide 7
Email Marketing Tools
Choosing a good tool involves considering:
1. Deliverability: Email delivery rate.
2. Inbox Placement: Reaching inbox, not spam or promotions.
3. Ease of Use: Simplicity of use.
4. Cost: Affordability.
5. List Maintenance: Keeping the list clean.
6. Features: Regular features like Broadcast and Sequence.
7. Automation: Better with automation.
Slide 8
Top 5 Email Marketing Tools:
1. ConvertKit
2. Get Response
3. Mailchimp
4. Active Campaign
5. Aweber
Slide 9
Email Marketing Strategy
To get good results, consider:
1. Build your own list.
2. Never buy leads.
3. Respect your customers.
4. Always provide value.
5. Don’t email just to sell.
6. Write heartfelt emails.
7. Stick to a schedule.
8. Use photos and videos.
9. Segment your list.
10. Personalize emails.
11. Ensure mobile-friendliness.
12. Optimize timing.
13. Keep designs clean.
14. Remove cold leads.
Slide 10
Uses of Email Marketing:
1. Affiliate Marketing
2. Blogging
3. Customer Relationship Management (CRM)
4. Newsletter Circulation
5. Transaction Notifications
6. Information Dissemination
7. Gathering Feedback
8. Selling Courses
9. Selling Products/Services
Read Full Article:
https://digitalsamaaj.com/is-email-marketing-effective-in-2024/
How to Show Sample Data in Tree and Kanban View in Odoo 17Celine George
In Odoo 17, sample data serves as a valuable resource for users seeking to familiarize themselves with the functionalities and capabilities of the software prior to integrating their own information. In this slide we are going to discuss about how to show sample data to a tree view and a kanban view.
No, it's not a robot: prompt writing for investigative journalismPaul Bradshaw
How to use generative AI tools like ChatGPT and Gemini to generate story ideas for investigations, identify potential sources, and help with coding and writing.
A talk from the Centre for Investigative Journalism Summer School, July 2024
How to Configure Time Off Types in Odoo 17Celine George
Now we can take look into how to configure time off types in odoo 17 through this slide. Time-off types are used to grant or request different types of leave. Only then the authorities will have a clear view or a clear understanding of what kind of leave the employee is taking.
How to Store Data on the Odoo 17 WebsiteCeline George
Here we are going to discuss how to store data in Odoo 17 Website.
It includes defining a model with few fields in it. Add demo data into the model using data directory. Also using a controller, pass the values into the template while rendering it and display the values in the website.
Understanding and Interpreting Teachers’ TPACK for Teaching Multimodalities i...Neny Isharyanti
Presented as a plenary session in iTELL 2024 in Salatiga on 4 July 2024.
The plenary focuses on understanding and intepreting relevant TPACK competence for teachers to be adept in teaching multimodality in the digital age. It juxtaposes the results of research on multimodality with its contextual implementation in the teaching of English subject in the Indonesian Emancipated Curriculum.
Join educators from the US and worldwide at this year’s conference, themed “Strategies for Proficiency & Acquisition,” to learn from top experts in world language teaching.
1. BY
Dr. SURYAKANT B. BORUL
M. Sc., M.Phil., Ph. D.
Head & Assistant Professor,
Department of Chemistry,
Late Ku. Durga K. Banmeru Science
College, Lonar. Dist. Buldana. 443302.
LATE KU. DURGA K. BANMERU SCIENCE
COLLEGE, LONAR, DIST. BULDANA. 443302.
(Affiliated to Sant Gadage Baba Amravati University Amravati; 2 (f) & 12 B; NAAC Accredited with ‘C’ grade)
3. Ionic Bonding-
Defn- “The chemical bond which is formed by transfer of one or more
electrons from the valence shell of one atom to the valence shell of another
atom is called as ionic bond.”
Or “The chemical bond which is formed due to electrostatics force of
attraction in between opposite charge ions is called as ionic bond.”
For example – Bond in between Na and Cl
Na + Cl [Na+] [Cl-] or Na+Cl-
(2,8,1) (2,8,7) (2,8) (2,8,8)
5. The formation of an ionic bond is favoured when-
1) Metals has low ionization energy
2) Other elements has high electron affinity and
3) The resulting compound has lattice energy.
6. Types of Cations
The formation of an ionic compound is due to atom attaining electronic
configuration similar to that of inert gas element by an anion while the cation may
achieve any one of the following configurations.
1. No valence electron (Ex.- H+)
2. Ions with inert gas configuration–These ions have inert gas e. c. (ns2np6) in
their outermost shell. (Except foe n=1).
Cations Inert Gas
Li+ He (1s2)
Na +, Mg 2+, Al 3+ Ne (2s2 2p6)
K+, Ca+, Sc3+ , Ti4+ Ar (3s2 3p6)
Rb+ , Sr2+ , Y3+, Zr4+, Kr (4s2 4p6)
Cs+ , Ba2+ , La3+ , Ce4+ Xe (5s2 5p6)
7. 3. Ions with pseudo inert gas configuration (ns2np6nd10)– These ions
have inert gas e.c. (ns2 np6 nd10) in their outermost shell.
Cations Electronic Configuration
Ag+ , Cd 2+, In3+, Sn4+ 4s2 4p6 4d10
Au+ , Hg 2+,Ti3+, Pb4+ 5s2 5p6 5d10
4. The inert s2 pair configuration ((n-1)s2 p6 d10 ns2)–
When the elements having valence shell configuration ns2 npx
(x=1,2,3) lose their p electrons only, cations with ns2 configuration are
formed.
8. Cations Electronic Configuration
Ga+ , Ge 2+ and As3+ 4s2
In+ , Sn 2+ and Sb3+ 5s2
Ti+ , Pb 2+ and Bi3+ 6s2
This is possible only when the energies of the ns & np electrons
differ sufficiently so as to result in the stepwise ionization during the
chemical bond formation. Therefore, only the post transition elements of
group IIA, IV A and VA give such ions.
9. 5. The d and f ions:- The transition metal ions formed by the loss of the outer
valence shell electrons without the ionization of the d electrons have the
configuration of the outer shell as- ns2 np6 ndx (x= 1 to 9) and are classified
as the d ions.
Ex: Ti2+ , V2+ , Cr2+ , Co2+ etc.
The ions are derived from the inner transition elements by the loss of
the outer s and d electrons and have configuration. (n-1) s2 ,(n-1)p6, (n-
2)d10, (n-2)f1-13 ex.- Lanthanide and actinide ions.
6. Ions with Irregular configurations:- These are certain ions that cannot be
classified into any particular class
Ex: Ga4+
10. Energetics of Ionic Bond Formation
Their are three types of energies are involved in the ionic bond
formation. These are as follows
A) Ionization energy
B) Electron affinity or energy
C) Lattice energy
A) Ionization energy-
“The amount of energy required to remove the outer most electron
from an isolated gaseous atom of an element in its ground state to form
cation is called as ionization energy.”
11. M(g) M(g) + e- ; H = +I
The energy required for this change is denoted by I.
The energy is to be supplied in the process it is given a positive sign.
The energy is measured in electron volts (eV) or Kcal / mole.
The magnitude of ionization energy is a direct measure of ease of cation
formation.
If its value is low. Cation is readily formed. Alkali and alkaline earth
metals have low values of ionization energy.
12. B) Electron affinity or energy-
“The amount of energy released when an electron is added to an
isolated neutral gaseous atom in its ground state to produce an anion is
called as electron affinity or energy.”
X(g) + e- X-
(g); H = -E
It is denoted by E.
It is the energy released, it is given a negative sign.
The energy is measured in electron volts(eV) or Kcal/ mole.
Anion formation will be favoured if more energy is released in above
process i.e. if electron affinity is high.
13. C) Lattice energy- It is related to the formation of an ionic solid from its
ions. Lattice energy of an ionic crystal M+ X- is defined in the following
two ways-
1. The energy released when exact number of gaseous cations M+
(g) and gaseous
anions X-
(g) come close together from infinity to from one mole of solid ionic
crystal, M+ X-
(S) is called as lattice energy.
M+
(g) + X-
(g) M+ X-
(S) + Energy released
2. The energy required for removing ions of one mole of solid ionic crystal from
their equilibrium positions in crystal to affinity is called as lattice energy.
M+ X-
(S) + Energy supplied M+
(g) + X-
(g)
It is denoted as U
15. Ionic Bonding-
Defn- “The chemical bond which is formed by transfer of one or more
electrons from the valence shell of one atom to the valence shell of another
atom is called as ionic bond.”
Or “The chemical bond which is formed due to electrostatics force of
attraction in between opposite charge ions is called as ionic bond.”
For example – Bond in between Na and Cl
Na + Cl [Na+] [Cl-] or Na+Cl-
(2,8,1) (2,8,7) (2,8) (2,8,8)
16. C) Lattice energy- It is related to the formation of an ionic solid from its
ions. Lattice energy of an ionic crystal M+ X- is defined in the following
two ways-
1. The energy released when exact number of gaseous cations M+
(g) and gaseous
anions X-
(g) come close together from infinity to from one mole of solid ionic
crystal, M+ X-
(S) is called as lattice energy.
M+
(g) + X-
(g) M+ X-
(S) + Energy released
2. The energy required for removing ions of one mole of solid ionic crystal from
their equilibrium positions in crystal to affinity is called as lattice energy.
M+ X-
(S) + Energy supplied M+
(g) + X-
(g)
It is denoted as U
17. Factors favouring the Formation of Ionic
Bond
The formation of an ionic compound MX will be favoured if
i) The Ionization energy of element is low
ii) Electron affinity or energy of X is high
iii) Lattice energy of compound MX is high
Calculation of lattice energy- Lattice energy may be calculated
theoretically using Madelung constant or it may be determined
experimentally using Born Haber cycle. Both the methods are
discussed as-
18. Theoretical Calculation of Lattice energy using Madelung
constant
In 1918 Max Born and Alfred Landé proposed that the lattice energy
could be derived from the electrostatic potential of the ionic lattice and a
repulsive potential energy term. Lattice energy can be theoretically calculated
using the Born-Lande equation.
Where e = Charge on electron (1.6022X 10-19C)
Z+ and Z- = Charge on cation and anion respectively
NA= Avogadro number (6.023 x 1023); n = Born Exponent
r = Distance between nuclei of cation and anion in cm.
U= Lattice energy of the ionic compound
M= Madelung (From name of Erwin Madelung, a German physicist)
19. Madelung constant-
It is a correction factor which takes into account the electrostatic forces
exerted by neighboring ion pair. It entirely depends upon the arrangement of
positive and negative ions in crystal, i.e. upon the geometry of the ionic crystal.
It does not depends upon the nature of ions present in the crystal.
It can be calculated by summing the mutual potential energies of all the
ions a lattice. Values of Modelung constants for some common crystal are as-
Crystal type Modelung constant
NaCl 1.747558
CaCl 1.762670
CaF2 5.03878
TiO2 4.816
20. Born exponent-
It is a repulsion exponent which allows for repulsive forced between the
electron clouds of oppositely charged ions. It can be evaluated from the results
of experimental measurements of the compressibility of the crystal.
It is found that for all the crystals n lies in the neighbouring of 9. It
depends upon configuration of ion.
For the different configuration the values are as –
He= 5, Ne=7, Ar=9, Kr=10, Xe=12
For a crystal having two ions of different electronic configuration average of the
values given above is used. For ex.-in case of NaCl, Na+ ion has configuration of
neon (n=7) and Cl - has configuration of argon (n=9). Thus evaluation of lattice
energy of NaCl the value of n to be used 8.
21. Experimental Determination of Lattice Energy using Born
Haber cycle
The lattice energy of an ionic solid like NaCl may be determined by
using Born-Haber Cycle. It is a thermo-chemical cycle and was devised by
Born and Haber in 1919.
The cycle first relates the lattice energy of crystalline solid
(unknown quantity) to other known thermo-chemical quantities. Then the
use of Hess’s law to evaluate the unknown quantity.
22. Lattice energy of sodium chloride may be determined by
using Born-Haber cycle as follows
Sodium chloride may be considered to be formed solid sodium metal
and gaseous chlorine by two different methods described below:
Method 1: It is the direct combination of solid sodium and gaseous chlorine
to give solid sodium chloride. The process may be represented by following
equation.
Na(s) + 1/2 Cl2(g)→ Na Cl (s); H, = -414.2 kJ/mol
23. This equation tells us that when one mole of solid sodium combines
with half mole of gaseous chlorine molecules, one mole of crystalline sodium
chloride is formed. During this process 414.2 kJ mol of energy is also
evolved. This energy is called heat of formation of sodium chloride and is
represented by the symbol H.
Method 2 : It involves five different steps described below
Step 1 : Sublimation of Sodium: In this process 1 mole of solid sodium
Na(s) changes to gaseous sodium Na(s). The energy required for this process
is SNa (Heat of sublimation of sodium) Its value is experimentally found out
to be 108.7 kJ/mol.
Na(s) → Na(g) ; SNa = 108.7 kJ/mol
24. Step 2: Dissociation of chlorine: In this process half mole of chlorine is
dissociated into 1mole of chlorine atoms. The energy required for this process
is 1/2 DCl2 (where DCl2, is the heat of dissociation of one mole of chlorine).
Experimental value of 1/2 DCl2 is 112.95 kJ/mol
Cl2(g) Cl(g) ; 1/2 DCl2 = 112.95 kJ/mol
Step 3: Formation of sodium ions: 1 mole of gaseous sodium atoms are
converted to sodium ions by removal of an electron from each of them.
Energy required for this process is INa .(Ionization energy of sodium) Its
experimental value is 489.5 kJ/mol.
Na(g) Na+
(g) + e- INa = 489.5 kJ/ mol
25. Step 4: Formation of chloride ions: One mole of chlorine atoms (formed in
step 2) take up electrons given by sodium and are converted to negatively
charged chloride ions. The process is accompanied by release of energy. By
definition the energy released in this process is electron affinity of chlorine
(ECl). Its experimental value is -351.4 kJ/mol
Cl(g) + e-→ Cl-
(g) ; ECl2= -351 kJ/ mol
Step 5: Formation of ionic crystal Na+Cl-
(s) : Gaseous sodium and chloride
ions formed instep (3) and (4) above combine to give solid sodium chloride
crystal Na+Cl-
(s). Energy is related in this process also and by definition of
lattice energy of NaCl.
26. It is represented by UNaCl. Its value is to be determine fro other
values.
Na+
(g) + Cl-
(g) → Na+Cl- ; UNaCl = ?
According to Hess’s law the energy change in method (1) must be
equal to total of energy changes of all steps in method (2) i.e.
Hf = SNa + ½ DCl2 + INa + ECl2 + UNaCl
Putting the actual values we gets.
-414.2 = +108.7 +1/2*225.9 + 489.5 - 351.4 + UNaCl
Therefore
UNaCl = -414.2 -108.7 – 112.95- 489.5 + 351.4
UNaCl = -773.95KJ/Mol
28. Experimental Determination of Lattice Energy using Born
Haber cycle
The lattice energy of an ionic solid like NaCl may be determined by
using Born-Haber Cycle. It is a thermo-chemical cycle and was devised by
Born and Haber in 1919.
The cycle first relates the lattice energy of crystalline solid
(unknown quantity) to other known thermo-chemical quantities. Then the
use of Hess’s law to evaluate the unknown quantity.
29. Lattice energy of sodium chloride may be determined by
using Born-Haber cycle as follows
Sodium chloride may be considered to be formed solid sodium metal
and gaseous chlorine by two different methods described below:
Method 1: It is the direct combination of solid sodium and gaseous chlorine
to give solid sodium chloride. The process may be represented by following
equation.
Na(s) + 1/2 Cl2(g)→ Na Cl (s); H, = -414.2 kJ/mol
30. This equation tells us that when one mole of solid sodium combines
with half mole of gaseous chlorine molecules, one mole of crystalline sodium
chloride is formed. During this process 414.2 kJ mol of energy is also
evolved. This energy is called heat of formation of sodium chloride and is
represented by the symbol H.
Method 2 : It involves five different steps described below
Step 1 : Sublimation of Sodium: In this process 1 mole of solid sodium
Na(s) changes to gaseous sodium Na(s). The energy required for this process
is SNa (Heat of sublimation of sodium) Its value is experimentally found out
to be 108.7 kJ/mol.
Na(s) → Na(g) ; SNa = 108.7 kJ/mol
31. Step 2: Dissociation of chlorine: In this process half mole of chlorine is
dissociated into 1mole of chlorine atoms. The energy required for this process
is 1/2 DCl2 (where DCl2, is the heat of dissociation of one mole of chlorine).
Experimental value of 1/2 DCl2 is 112.95 kJ/mol
Cl2(g) Cl(g) ; 1/2 DCl2 = 112.95 kJ/mol
Step 3: Formation of sodium ions: 1 mole of gaseous sodium atoms are
converted to sodium ions by removal of an electron from each of them.
Energy required for this process is INa .(Ionization energy of sodium) Its
experimental value is 489.5 kJ/mol.
Na(g) Na+
(g) + e- INa = 489.5 kJ/ mol
32. Step 4: Formation of chloride ions: One mole of chlorine atoms (formed in
step 2) take up electrons given by sodium and are converted to negatively
charged chloride ions. The process is accompanied by release of energy. By
definition the energy released in this process is electron affinity of chlorine
(ECl). Its experimental value is -351.4 kJ/mol
Cl(g) + e-→ Cl-
(g) ; ECl2= -351 kJ/ mol
Step 5: Formation of ionic crystal Na+Cl-
(s) : Gaseous sodium and chloride
ions formed instep (3) and (4) above combine to give solid sodium chloride
crystal Na+Cl-
(s). Energy is related in this process also and by definition of
lattice energy of NaCl.
33. It is represented by UNaCl. Its value is to be determine fro other
values.
Na+
(g) + Cl-
(g) → Na+Cl- ; UNaCl = ?
According to Hess’s law the energy change in method (1) must be
equal to total of energy changes of all steps in method (2) i.e.
Hf = SNa + ½ DCl2 + INa + ECl2 + UNaCl
Putting the actual values we gets.
-414.2 = +108.7 +1/2*225.9 + 489.5 - 351.4 + UNaCl
Therefore
UNaCl = -414.2 -108.7 – 112.95- 489.5 + 351.4
UNaCl = -773.95KJ/Mol
35. Problem based on Lattice Energy
1) To calculate the lattice energy of NaCl crystal the data is-
Sublimation energy of Na (SNa)=108.710 Kj/ Mol
Dissociation energy for Cl2(DCl2)=225.9 Kj/ Mol
Ionization energy for Na(g) (ECl2)=489.5 Kj/ Mol
Electron affinity for Cl(g) (INa)=-351.4 Kj/ Mol
Heat of formation of NaCl (Hf ) = -414.2 Kj/ Mol
Ans-
We know that,
Hf = SNa + ½DCl2 + INa + ECl2 + UNaCl
Na+ + Cl- → Na+Cl- ; UNaCl = ?
UNaCl = -414.2 -108.7 – 112.95- 489.5 + 351.4
UNaCl = -773.95KJ/Mol
36. 2) To calculate the heat of reaction of KF from its elements from the following
data by use of Born Haber cycle. Sublimation energy of K (SK)=87.8 Kj/
Mol
Dissociation energy for F2(DF2)=158.9 Kj/ Mol
Ionization energy for K(g) (IK)= 414.2 Kj/ Mol
Electron affinity for F(g) (EF2)= -334.7 Kj/ Mol
Lattice energy for KF(UKF)= -807.5 Kj/ Mol
Heat of formation of KF (Hf ) = ?
Ans- We know that,
Hf = SK + ½DF2 + IK + EF2 + UKF
K(S) + ½ F2(g) → KF (S) ; Hf =?
Hf = 87.8 + ½(158.9) + 414.2 + (-334.7) + (-807.5)
Hf = 87.8 + 79.45 + 414.2 + (-1142.2)= 581.45-1142.2=-560.75
Heat of formation of KF (Hf ) = -560.75KJ/Mol
37. 3) To calculate the heat of reaction of MgF2 from its elements by using of Born
Haber cycle. Thermochemical data as-
Sublimation energy of Mg (SMg)=146.4 Kj/ Mol
Dissociation energy for F2(DF2)=158.9 Kj/ Mol
Ionization energy for Mg(g) (IMg)= 2184.0 Kj/ Mol
Electron affinity for F(g) (EF2)= -334.7 Kj/ Mol
Lattice energy for MgF2(U)= -2922.5 Kj/ Mol
Heat of formation of MgF2 (Hf ) = ?
Ans- We know that,
Hf = SMg + DF2 + IMg + EF2 + UMgF2
Mg(S) + F2(g) → MgF2(S) ; Hf =?
Hf = 146.4 + 158.9 + 2184 + 2(-334.7) +(-2922.5)
Hf = 146.4 + 158.9 + 2184 -669.4 -2922.5=2489.3-3591.9
Heat of formation of MgF2 (Hf ) = -1102.6KJ/Mol
38. Solvation of Ions and Solvation Energy
Q.-Explain the term Solvation energy.
Ans- “The interaction that takes place when a substance is introduced in a
solvent is called as solvation and the energy associated with this is called as
solvation energy.”
Water is called a polar solvent because in its molecule the oxygen
atom is partly negatively charged and each hydrogen atom is partly
positively changed as -
39. When sodium chloride is introduced in such a solvent, the negative
end of water molecule attract the positive ions, and the positive end attract
the negative ions of the crystal.
These attraction forces exerted by the water molecules weaken the
attractions existing among the ions in the crystal.
Hence some of the ions in the crystal are pulled away from their positions in
crystal lattice as -
42. Once the Na+ and Cl- ions are broken away from the ionic lattice,
following two processes occur same time.
1. Each sodium ion is surrounded by a definite but unknown number of
water molecules, say ‘x’, with their negative ends (oxygen ends)
pointing towards it, as shown in figure.
Na+ + xH2O = [Na(H2O)x]+
This process is called solvation of sodium ion and the energy change
associated with it is called as solvation energy of sodium ion, (Hs)Na+.
The chemical species [Na(H2O)x]+ is called solvated or acquated sodium
ion and may also be represented as [Na(aq)]+ .
43. 2) Each chloride ion is surrounded by definite but unknown number of water
molecules, say ‘y’ with their positive ends (hydrogen ends) pointing
towards it, as shown
Cl- + yH2O = [Cl(H2O)y]-
The process is called solvation of chloride ion and the energy change
associated with it is called solvation energy of chloride ion, (Hs)Cl-. The
chemical species [Cl(H2O)y]- is called solvated or aquated chloride ion and
may also be represented as [Cl(aq)]-
44. The total process may be written as:
NaCl(s) + (x+y)H2O [Na (H2O)x]+ + [Cl(H2O)y]-
or NaCl(s) + aq Na+
(aq) + Cl-
aq)
fig- Born-Haber cycle for determination of salvation energy.
45. Calculation of Solvation Energy
The energy changes during solvation of sodium and chloride ions may be
calculated using a Born-Haber type cycle as given in figure 1.6
Here L is the heat of solution of NaCl at infinite dilution (i.e. the
total amount of heat evolved or absorbed when one mole of sodium
chloride dissolved in such a large excess of water, that further addition of
water does not produce any heat change).
UNaCl is the lattice energy of NaCl.
(HS)Na+ and (Hs)Cl- are the solvation energies of sodium and
chloride ions.
46. Since heat of solution of NaCl at infinite dilution (L) and lattice
energy of NaCl (UNaCl) are experimentally known, the solvation energies
Na+ and Cl- ions can be calculated from following relation.
L = UNaCl + (HS)Na+ + (HS)cı-
It gives us the sum of solvation energies of sodium and chloride
ions. (There is no purely thermochemical way to separate this sum into
two parts corresponding to sodium and chloride ions.
47. Factors affecting solvation and solvation energy
i) Solvation energy and lattice energy: The dissolution of an ionic
compound in polar solvent is favoured if the attraction between solvent
molecules and ions, exceeds the attraction among the ions in a crystal
lattice or in other words if the energy of solvation of ions exceeds the
lattice energy of the crystal.
ii) Dielectric constant and solvation energy: For a given ion and the
solvent the dielectric constant and the solvent energy are related by
following equation, called Born equation.
48. Here,
H = Solvation energy of gaseous ion,
r = ionic radius and or
C = charge on the ion,
D = dielectric constant of the solvent.
From this equation it is evident that increase in the magnitude of
dielectric constant increases the solvation energy.
iii) Ionic size: Both solvation energy and lattice energy are increased by
decreases in cation and anion size. It is therefore difficult to relate solubility to
size of ion.
49. iv) However the two opposite charges are not of the same magnitude and in
general other factors being equal solubility increases with increase in
cation or anion size.
v) Ionic charge: With increasing cation or anion charge, the lattice energy
increases much more rapidly than the solvation energy. This results in
decrease of solubility.
vi) Electronic configuration of cations and their polarising effect:
a) If the anion is more readily polarized by the cation, than is the solvent,
the lattice energy will increase more than solvation energy and the
solubility will decrease.
b) If the solvent is more readily polarized by the cation, the solubility will
increase.
50. The ions having pseudo inert gas configuration Ag+, Pb++, Hg++,
etc. have high anion polarizing effect, hence their salts (AgCl, PbCl, HgCl)
have lower solubility in water, As compared to these, the alkaline earth
cations (Ca+, Ba++ etc.) having inert gas type configuration, have low anion
polarizing effect, hence their halides CaCl2, BaCl2, are readily soluble in
water.