Chapter 6. Electronic Structure and Chemical Periodicity

1. Chapter 6.Electronic Structure and Chemical Periodicity The Periodic Law states that when elements are arranged in order of increasing atomic number, elements with similar chemical properties occur at periodic (regularly spaced) intervals. Tom Lehrer's Elements in Song

2. The Periodic Table A Periodic Table is a tabular arrange-ment of the elements, in order of atomic number, in which elements with similar chemical properties are grouped in columns. Several attempts were made to group elements in the mid-1800's. The one that worked was developed in Russia, by Dmitri Mendeleev, in 1869.

3. Dmitri Mendeleev

4. Mendeleev's Periodic Table

5. Mendeleev's Predictions for Undiscovered Elements

6. Periodic Table of the Elements

7. The Periodic Table and Electronic Structure of Atoms The Periodic Law follows from the electronic structures of atoms. The outermost electrons in the atoms of an element are responsible its properties. Valence electrons, or distinguishing electrons, are the outermost electrons in an atom.

8. Electron Energies are QuantizedThey Occur in steps Atomic Spectra of Elements

9. Steps Within the Steps An Electron Shell is a region of space around a nucleus that contains electrons that have similar energies, and similar distances from the nucleus. An Electron Subshell is a subdivision of a shell, in which all the electrons have exactly the same energy and distance from the nucleus. An Electron Orbital is a region of space in a subshell where one or two electrons with a specific energy are likely to be found.

10. Electron Shells and Subshells

11. Electron Shells and Subshells

12. Steps Within the Steps An Electron shell contains 2(n2) electrons Electron subshells have characteristic numbers of orbitals and electrons. Subshell # of orbitals # of electrons s 1 2 p 3 6 d 5 10 f 7 14

13. Shapes of Orbitals An Electron Orbital is a region of space in a subshell where one or two electrons with a specific energy are likely to be found.

14. How Three p Orbitals Make up a p Subshell

15. Energy Levels of Subshells Get a Bit Shuffled

16. Aufbau Diagram: Order of Fillingfor Subshells

17. Periodic Table, Showing Subshells That Contains Valence Electrons for Various Elements

18. Periodic Table, Showing Shell Number for Valence Electrons

19. Periodic Table Showing How Inner Transition Elements Fit into the Main Table

20. The modern Periodic Table. Elements with similar chemical properties fall in the same vertical column.

21. Vocabulary of Periodic Table Group (family) of elements--vertical column Period (row) of elements--horizontal row Group 1A: Alkali Metals Group 2A: Alkaline Earth Metals Group 7A: Halogens Group 8A: Noble Gases Groups 1A – 8A: Representative Elements Groups 1B – 8B: Transition Metals

22. Vocabulary of Periodic Table Pink: Representative Metals Orange: Transition Metals Yellow: Inner Transition Metals Purple: Post-Transition Metals Aqua: Metalloids, a.k.a Semimetals Green: Nonmetals

23. Properties of Metals, Metalloids, and Nonmetals.

24. Effective Nuclear Charge (Zeff) Zeff is the charge actually felt by an electron Outer electrons are shielded by inner electrons.

25. Relative Sizes of Main Group Atoms

26. Ionization Energy is the energy required to pull an electron off an atom.

27. Electron Affinity is the energy released when a neutral atom gains an electron.

28. Electronegativity is a measure of the at-traction an atom has for electrons it is sharing in a chemical bond.

29. Cations are positively charged atoms that have lost electrons. They are always smaller than the parent atom.

30. Anions are negatively charged atoms that have gained electrons. They are always larger than the parent atom.