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Chemical Structure: Structure of Matter. Elements, Ions & Isotopes

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Lecture materials for the Introductory Chemistry course for Forensic Scientists, University of Lincoln, UK. See http://forensicchemistry.lincoln.ac.uk/ for more details.

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This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License Elements, Ions & Isotopes University of Lincoln presentation
What you should know… Elements and their classification Atoms/molecules Symbols of the elements Allotropy The Octet rule Ions – cations/anions Oxidation/reduction Ionisation energy/electron affinity Isotopes Atomic mass Relative atomic mass This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License
1. Elements This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License
IUPAC Definition An element is matter, all of whose atoms are alike in having the same positive charge on the nucleus International Union of Pure and Applied Chemistry This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License
Dictionary Definition A substance that cannot be decomposed into simpler substances This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License
Are all elements simply collections of atoms? YES, normally Elemental mercury (liquid), Hg Elemental copper, Cu Elemental helium (gas), He Elemental gold, Au This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License
Some elements only exist as molecules These elements exist as diatomic molecules* * A molecule is two or more atoms bonded together This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License H 2 N 2 O 2 F 2 Cl 2 Br 2 I 2
Symbols A = MASS NUMBER Z = ATOMIC NUMBER =number of protons N =number of neutrons A = N + Z X This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License Z A
For Example This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License 20 40 11 22 1 1 H Na Ca
Classification of elements Metals Non-metals Semi-metals This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License
This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License H Be Li Na K Rb Cs Fr Mg Ca Sr Ba Ra Sc Y La Ac Ti V Cr Mn Fe Co Ni Cu Zn Zr Hf Ta W Re Os Ir Pt Au Hg Tl Nb Mo Tc Ru Rh Pd Ag Cd In Sn Pb Bi Po At Rn Xe Kr Ar Ne Sb Te I Ga Al Ge Si P S Cl As Se Br Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr He B C N O F Metals Semi-metals Non-Metals Classification of elements
Allotropes Some elements exist in more than one structural form. This property is called ALLOTROPY Consider carbon – 2 common allotropes are graphite and diamond. Both consist only of atoms of carbon, C, but their structures are very different, and hence their properties differ This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License
Allotropes of Carbon This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License C 60 fullerene structure Graphite layered structure Diamond structure
Allotropes of other elements? Tin, Sn Phosphorus, P Arsenic, As Oxygen, O Sulphur, S Selenium, Se This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License
2. Ions This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License
The Octet Rule Because filled orbitals give the best STABILITY , all elements try to attain a noble gas configuration (i.e. 8 electrons in their valence shell) 2 ways of doing this: (i) losing electrons; or (ii) gaining electrons (which ever uses the least energy) This is the driving force behind the chemistry of the elements and is called the OCTET RULE This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License
The Periodic Table This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License n=1 n=2 n=3 n=4 n=5 n=6 n=7 The Periodic Table consists of rows of 8 elements (s + p block only) Each row corresponds to a different quantum number (n=1–7) Each column has the same VALENCE CONFIGURATION ns 1 ns 2 ns 2 np 1 ns 2 np 2 ns 2 np 3 ns 2 np 4 ns 2 np 5 ns 2 np 6 f - block elements H Be Li Na K Rb Cs Fr Mg Ca Sr Ba Ra Sc Y La Ac Ti V Cr Mn Fe Co Ni Cu Zn Zr Hf Ta W Re Os Ir Pt Au Hg Tl Nb Mo Tc Ru Rh Pd Ag Cd In Sn Pb Bi Po At Rn Xe Kr Ar Ne Sb Te I Ga Al Ge Si P S Cl As Se Br Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr He B C N O F Lanthanoids Actinoids d – block elements Hydrogen and s – block elements p – block elements
Definition An ION is a charged atom or molecule. There are 2 types of ion: A CATION is positively charged An ANION is negatively charged This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License
Cations Cations are formed when an atom loses 1 or more valence electron: Na  Na + + e - Mg  Mg 2+ + 2e - The loss of electrons is known as OXIDATION and is a typical reaction of metals This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License
Valence Electrons This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License [Ar] 4s 2 Ca 20 1s 2 2s 2 2p 6 Ne 10 [Ar] 4s 1 K 19 [He] 2s 2 2p 5 F 9 1s 2 2s 2 2p 6 3s 2 3p 6 Ar 18 [He] 2s 2 2p 4 O 8 [Ne] 3s 2 3p 5 Cl 17 [He] 2s 2 2p 3 N 7 [Ne] 3s 2 3p 4 S 16 [He] 2s 2 2p 2 C 6 [Ne] 3s 2 3p 3 P 15 [He] 2s 2 2p 1 B 5 [Ne] 3s 2 3p 2 Si 14 [He] 2s 2 Be 4 [Ne] 3s 2 3p 1 Al 13 [He] 2s 1 Li 3 [Ne] 3s 2 Mg 12 1s 2 He 2 [Ne] 3s 1 Na 11 1s 1 H 1 Electronic configuration Element Symbol Atomic number Electronic configuration Element Symbol Atomic number
Group 1 = [NG] ns 1 Group 2 = [NG] ns 2 Elements in these groups want to LOSE their outer (valence) electrons to gain the noble gas configuration [NG]: Na  Na + + e - Mg  Mg 2+ + 2e - Electronic configuration of both cations = [Ne] The energy required to remove a valence electron is called the IONISATION ENERGY Group 1 & 2 elements (metals) This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License Group 1 Group 2 Ra Fr Ba Cs Sr Rb Ca K Mg Na Be Li
Anions Anions are formed when an atom gains 1 or more valence electron: F + e -  F - O + 2e -  O 2- The gain of electrons is known as REDUCTION and is a typical reaction of non-metals This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License
Group 16 = [NG] ns 2 np 4 Group 17 = [NG] ns 2 np 5 Elements in these groups want to GAIN valence electrons to attain the noble gas configuration [NG] ns 2 np 6 , which is the noble gas sitting on their RHS in the Periodic Table F + e -  F - O + 2e -  O 2- Electronic configuration of both anions = [Ne] Electron affinity is a measure of how easy it is to gain a valence electron Group 16 & 17 elements (non-metals) This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License Groups 16 17 18 Se S O At I Br Cl F Rn Xe Kr Ar Ne
3. Isotopes This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License
Definition In 1913 Soddy proposed the existence of ISOTOPES Definition : Atoms of the same elements with different atomic masses This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License Frederick Soddy Nobel Prize (Chemistry) 1921
Definition Isotopes of an element have the same number of protons, but different numbers of neutrons Eg. This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License 29 29 Mass number (A) Atomic number (Z) Protons (Z) = 29 Neutrons (N) = 34 Protons (Z) = 29 Neutrons (N) = 36 Cu Cu 65 63
This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License Henri Becquerel Marie & Pierre Curie Radioactivity discovered in 1896
Stable v. Radioactive Isotopes This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License There are approximately 1,700 isotopes known to exist
Chart of the nuclides This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License
Chart of the nuclides This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License Black squares denote STABLE isotopes Z N
Atomic Mass, A For simplicity, atomic masses are given relative to the mass of 12 C 12 C = 12.0000 amu amu = atomic mass unit = 1.660x 10 -27 kg similar to the mass of a proton or neutron (see Lecture 1) Mass number (A) is used as the atomic mass This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License
Relative Atomic Mass, A r This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License Mg 24 78.7 Mg 25 10.1 Mg 26 11.2 % abundance The relative atomic mass of an element is the weighted mean of the atomic masses of all the stable isotopes for that element. For example: A r (Mg) = 24.3 Atomic mass
This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License Acknowledgements JISC HEA Centre for Educational Research and Development School of natural and applied sciences School of Journalism SirenFM http:// tango.freedesktop.org

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Chemical Structure: Structure of Matter. Elements, Ions & Isotopes

  • 1. This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License Elements, Ions & Isotopes University of Lincoln presentation
  • 2. What you should know… Elements and their classification Atoms/molecules Symbols of the elements Allotropy The Octet rule Ions – cations/anions Oxidation/reduction Ionisation energy/electron affinity Isotopes Atomic mass Relative atomic mass This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License
  • 3. 1. Elements This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License
  • 4. IUPAC Definition An element is matter, all of whose atoms are alike in having the same positive charge on the nucleus International Union of Pure and Applied Chemistry This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License
  • 5. Dictionary Definition A substance that cannot be decomposed into simpler substances This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License
  • 6. Are all elements simply collections of atoms? YES, normally Elemental mercury (liquid), Hg Elemental copper, Cu Elemental helium (gas), He Elemental gold, Au This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License
  • 7. Some elements only exist as molecules These elements exist as diatomic molecules* * A molecule is two or more atoms bonded together This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License H 2 N 2 O 2 F 2 Cl 2 Br 2 I 2
  • 8. Symbols A = MASS NUMBER Z = ATOMIC NUMBER =number of protons N =number of neutrons A = N + Z X This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License Z A
  • 9. For Example This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License 20 40 11 22 1 1 H Na Ca
  • 10. Classification of elements Metals Non-metals Semi-metals This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License
  • 11. This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License H Be Li Na K Rb Cs Fr Mg Ca Sr Ba Ra Sc Y La Ac Ti V Cr Mn Fe Co Ni Cu Zn Zr Hf Ta W Re Os Ir Pt Au Hg Tl Nb Mo Tc Ru Rh Pd Ag Cd In Sn Pb Bi Po At Rn Xe Kr Ar Ne Sb Te I Ga Al Ge Si P S Cl As Se Br Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr He B C N O F Metals Semi-metals Non-Metals Classification of elements
  • 12. Allotropes Some elements exist in more than one structural form. This property is called ALLOTROPY Consider carbon – 2 common allotropes are graphite and diamond. Both consist only of atoms of carbon, C, but their structures are very different, and hence their properties differ This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License
  • 13. Allotropes of Carbon This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License C 60 fullerene structure Graphite layered structure Diamond structure
  • 14. Allotropes of other elements? Tin, Sn Phosphorus, P Arsenic, As Oxygen, O Sulphur, S Selenium, Se This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License
  • 15. 2. Ions This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License
  • 16. The Octet Rule Because filled orbitals give the best STABILITY , all elements try to attain a noble gas configuration (i.e. 8 electrons in their valence shell) 2 ways of doing this: (i) losing electrons; or (ii) gaining electrons (which ever uses the least energy) This is the driving force behind the chemistry of the elements and is called the OCTET RULE This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License
  • 17. The Periodic Table This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License n=1 n=2 n=3 n=4 n=5 n=6 n=7 The Periodic Table consists of rows of 8 elements (s + p block only) Each row corresponds to a different quantum number (n=1–7) Each column has the same VALENCE CONFIGURATION ns 1 ns 2 ns 2 np 1 ns 2 np 2 ns 2 np 3 ns 2 np 4 ns 2 np 5 ns 2 np 6 f - block elements H Be Li Na K Rb Cs Fr Mg Ca Sr Ba Ra Sc Y La Ac Ti V Cr Mn Fe Co Ni Cu Zn Zr Hf Ta W Re Os Ir Pt Au Hg Tl Nb Mo Tc Ru Rh Pd Ag Cd In Sn Pb Bi Po At Rn Xe Kr Ar Ne Sb Te I Ga Al Ge Si P S Cl As Se Br Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr He B C N O F Lanthanoids Actinoids d – block elements Hydrogen and s – block elements p – block elements
  • 18. Definition An ION is a charged atom or molecule. There are 2 types of ion: A CATION is positively charged An ANION is negatively charged This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License
  • 19. Cations Cations are formed when an atom loses 1 or more valence electron: Na  Na + + e - Mg  Mg 2+ + 2e - The loss of electrons is known as OXIDATION and is a typical reaction of metals This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License
  • 20. Valence Electrons This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License [Ar] 4s 2 Ca 20 1s 2 2s 2 2p 6 Ne 10 [Ar] 4s 1 K 19 [He] 2s 2 2p 5 F 9 1s 2 2s 2 2p 6 3s 2 3p 6 Ar 18 [He] 2s 2 2p 4 O 8 [Ne] 3s 2 3p 5 Cl 17 [He] 2s 2 2p 3 N 7 [Ne] 3s 2 3p 4 S 16 [He] 2s 2 2p 2 C 6 [Ne] 3s 2 3p 3 P 15 [He] 2s 2 2p 1 B 5 [Ne] 3s 2 3p 2 Si 14 [He] 2s 2 Be 4 [Ne] 3s 2 3p 1 Al 13 [He] 2s 1 Li 3 [Ne] 3s 2 Mg 12 1s 2 He 2 [Ne] 3s 1 Na 11 1s 1 H 1 Electronic configuration Element Symbol Atomic number Electronic configuration Element Symbol Atomic number
  • 21. Group 1 = [NG] ns 1 Group 2 = [NG] ns 2 Elements in these groups want to LOSE their outer (valence) electrons to gain the noble gas configuration [NG]: Na  Na + + e - Mg  Mg 2+ + 2e - Electronic configuration of both cations = [Ne] The energy required to remove a valence electron is called the IONISATION ENERGY Group 1 & 2 elements (metals) This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License Group 1 Group 2 Ra Fr Ba Cs Sr Rb Ca K Mg Na Be Li
  • 22. Anions Anions are formed when an atom gains 1 or more valence electron: F + e -  F - O + 2e -  O 2- The gain of electrons is known as REDUCTION and is a typical reaction of non-metals This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License
  • 23. Group 16 = [NG] ns 2 np 4 Group 17 = [NG] ns 2 np 5 Elements in these groups want to GAIN valence electrons to attain the noble gas configuration [NG] ns 2 np 6 , which is the noble gas sitting on their RHS in the Periodic Table F + e -  F - O + 2e -  O 2- Electronic configuration of both anions = [Ne] Electron affinity is a measure of how easy it is to gain a valence electron Group 16 & 17 elements (non-metals) This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License Groups 16 17 18 Se S O At I Br Cl F Rn Xe Kr Ar Ne
  • 24. 3. Isotopes This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License
  • 25. Definition In 1913 Soddy proposed the existence of ISOTOPES Definition : Atoms of the same elements with different atomic masses This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License Frederick Soddy Nobel Prize (Chemistry) 1921
  • 26. Definition Isotopes of an element have the same number of protons, but different numbers of neutrons Eg. This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License 29 29 Mass number (A) Atomic number (Z) Protons (Z) = 29 Neutrons (N) = 34 Protons (Z) = 29 Neutrons (N) = 36 Cu Cu 65 63
  • 27. This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License Henri Becquerel Marie & Pierre Curie Radioactivity discovered in 1896
  • 28. Stable v. Radioactive Isotopes This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License There are approximately 1,700 isotopes known to exist
  • 29. Chart of the nuclides This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License
  • 30. Chart of the nuclides This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License Black squares denote STABLE isotopes Z N
  • 31. Atomic Mass, A For simplicity, atomic masses are given relative to the mass of 12 C 12 C = 12.0000 amu amu = atomic mass unit = 1.660x 10 -27 kg similar to the mass of a proton or neutron (see Lecture 1) Mass number (A) is used as the atomic mass This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License
  • 32. Relative Atomic Mass, A r This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License Mg 24 78.7 Mg 25 10.1 Mg 26 11.2 % abundance The relative atomic mass of an element is the weighted mean of the atomic masses of all the stable isotopes for that element. For example: A r (Mg) = 24.3 Atomic mass
  • 33. This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License Acknowledgements JISC HEA Centre for Educational Research and Development School of natural and applied sciences School of Journalism SirenFM http:// tango.freedesktop.org