The Periodic Table

1. The Periodic Table Chapter 6

2. A quest for accurate reproduction • J.W. Dobereiner – published his triad classification system (ex. Cl,Br,I similar chemical properties) • 1860 • Scientists agreed upon a method to measure mass • Are masses related to elemental properties? • John Newlands • Noticed every 8th element had similar properties • Law of octaves

3. The Law of Octaves

4. Dimitri Mendeleev - 1869 • Organized the periodic table based on increasing atomic mass • Predicted the properties of unknown elements • Sc, Ge, Ga P. 181 - Q 24, 25

6. Henry Moseley • Arranged elements based on the number of protons • Determined periodic law • Groups have similar properties • Properties change as you move across a period • Pattern repeats one period to the next P.181 - Q – 26, 27

8. Terminology • Groups (Families) – (IUPAC labels 1-18) • Periods • Representative elements(1A – 8A) • Wide array of chemical and physical properties • Group number indicates number of valance electrons • Transition elements • Metalloids • Metal • Non metals P. 181 - Q - 31

9. Metals • Shiny, smooth • Good electrical and heat conductors • Malleable, ductile • Solid at room temp • Reactive Alkali’s and Alkaline’s (s block)

10. Transition Metals • D and F (Inner transitional metals) block • Lanthanides and Actinides P. 181 - Q 33, 34, 35 – P. 182 – 48, 49, 53, 54

11. Non-Metals • Most of p block • gases or brittle solids (Br) • Little luster • Poor conductors • Halogens very reactive • Noble Gases (Inert Gases) - extremely unreactive due to filled s and p sublevels P. 181 – 28, 32

12. Metalloids • Share properties of metals and non-metals • Heavy step line – B, Si, Ge, As, Sb, Te, Po, At • Found in p block P. 181 - 29

13. Atomic Radius Metals - Half the distance between adjacent nuclei in a crystal of an element. Non Metals - Half the distance between bonded atoms of the same element (diatomic molecule).

14. Atomic Radius – Family Trends Atomic charge and occupied energy levels increase. Occupied orbitals shield electrons in the outer most energy level from the pull of the nucleus. Increases

15. Atomic Radius – Period Trends decreases • Increasing positive charge pulls the valence electrons closer to the nucleus. • Shielding does not influence this trend because the effect is constant. P. 181 - Q - 36 - P. 182 - Q - 50

16. Ions – Atoms gain or lose electrons to have a complete set of valence electrons (Octet Rule) Empty outer orbital or energy level makes it smaller. Electrostatic repulsion decreases. 11 p  10 e Na Na+1 11 protons 11 electrons 11 protons 10 electrons

17. Increased electrostatic repulsion Cl 17 Protons 17 Electrons Cl1- 17 Protons 18 Electrons

18. Ionic Radius – Family Trends • Principle energy levels increase in size.

19. Ionic Radius – Period Trends 3 protons 2 electrons 4 protons 2 electrons 5 protons 2 electrons 6 protons 2 electrons 7 protons 10 electrons 8 protons 10 electrons 9 protons 10 electrons Electron repulsion decrease Electron repulsion decrease P. 181 - Q - 41, 42 - P. 182 - Q -52 - P. 183 - Q - 64, 65

20. Ionization Energy – energy needed for an atom to lose an electron Be  Be+  Be2+  Be3+ kilojoules/mol or kj/mol 1s2 1s2 1s2 1s1 2s2 2s1

21. 1st ionization energies increase as you move across a period due to the increased attraction of the nuclear charge. The stability of the filled sub level affects the ionization energy. P. 181 – Q - 37, 38, 40 – P. 182 – Q – 55, 58 – P. 183 – Q – 67B

22. Ionization Energy – Family Trends Decreases as you move down a family. The further the electron from the nucleus the easier it is to remove. P. 181 - Q - 39

23. Electronegativity – a measure of an atom’s ability to attract an electron P. 181 - Q - 43, 44, 45