Chapter 5

1. Chapter 5 The Periodic Table Chemistry

2. History of the Periodic Table • StanislaoCannizzaro(1826-1910) • Found a method to determine atomic mass • Dimitri Mendeleev (1834-1907) • “Father of the Periodic Table” • Made the first accepted Periodic Table • Noticed trends and left empty spaces for “missing” elements **By 1860 more than 60 elements were known**

3. History of the Periodic Table • Henry Moseley (1887 – 1915) • Found a method to determine atomic number(# of protons)

4. Periodic Law • Properties of elements are based on atomic number and valence electrons • The Modern Periodic Table • Arranged by increasing atomic number so elements with similar properties fall in the same columns • Newest sections added: Lanthanides, Actinides, Noble Gases

5. Electron Configurations Revisited • Valence Electrons: • Outer Shell Electrons • Have the Highest Principle Quantum Number • Determine many properties of the atoms • Were the “dots” on the dot diagram from last chapter!

6. Electron Configurations Revisited Periodic Table Arrangement:

7. Period Prediction Located in PERIOD 4 Highest Principle QN Using only the ELECTRON CONFIGURATION… Example: 1s22s22p63s23p64s23d104p3

8. Group Prediction Located in Group 15 – Add the electrons from the highest period (includes s, d if any, and p if any) Using only the Electron Configuration… Example: 1s22s22p63s23p64s23d104p3

9. Blocks on the Periodic Table • s – Block • Group 1 = Alkali Metals • Soft • Extremely reactive • (but…Hydrogen is NOT a metal) • 1 valence electron

10. Blocks on the Periodic Table • s-Block • Group 2 = Alkaline-Earth Metals • 2 valence electrons • Reactive but less than Group 1

11. Blocks on the Periodic Table • p block: • Groups 13-18 • Properties vary greatly (due to “steps”) • Valence Electrons = Group # - 10 • Example:

12. Blocks on the Periodic Table A halogen lamp also uses a tungsten filament, but it is encased inside a much smaller quartz envelope. Because the envelope is so close to the filament, it would melt if it were made from glass. The gas inside the envelope is also different -- it consists of a gas from the halogen group. These gases have a very interesting property: They combine with tungsten vapor. If the temperature is high enough, the halogen gas will combine with tungsten atoms as they evaporate and redeposit them on the filament. This recycling process lets the filament last a lot longer. In addition, it is now possible to run the filament hotter, meaning you get more light per unit of energy. You still get a lot of heat, though; and because the quartz envelope is so close to the filament, it is extremely hot compared to a normal light bulb. • p block: • Group 17 = Halogens • Very reactive

13. Blocks on the Periodic Table Neon signs are luminous-tube signs that contain neon or other inert gases at a low pressure. Applying a high voltage (usually a few thousand volts) makes the gas glow brightly. They are produced by the craft of bending glass tubing into shapes. A worker skilled in this craft is known as a glass bender, neon or tube bender. • p block: • Group 18 = Noble Gases • Very unreactive • They have a stable (full) valence octet • Many used in creating signs

14. Blocks on the Periodic Table • d block: • Groups 3-12 • Called the TRANSITION METALS • Luster, conductive, Malleable, Ductile • Hg is the ONLY liquid metal

15. Blocks on the Periodic Table Lanthanides Actinides f Block

16. Periodic Properties • “Trends” • Strength of Nucleus • Across a period – strength gets stronger • Atomic Number!! More protons = greater charge on nucleus B. Down a group – strength gets weaker • Size of atom is getting larger – e- in levels farther away – shielding attraction from nucleus

17. Periodic Properties • Atomic Radius (size of atom) • Across a period – radius gets smaller • Decreases across periods because of increasing positive charge • e- are pulled closer to a higher charged nucleus • Increased pull results in a smaller atomic radius • Down a group – radius gets bigger • Outer e- fill an s sublevel in a higher energy level farther from the nucleus

18. Periodic Properties • Ionization Energy - Energy to REMOVE an electron • ION – atom that has gained or lost an electron • Across a period – ionization energy increases • Increasing nuclear charge – pulls e- toward nucleus • Harder to pull away because of strong attraction B. Down a group – ionization energy decreases • Outer e- are farther away from nucleus – more easily removed. • Outer e- are also shielded from positive nucleus – weak attraction – easily removed

19. Periodic Properties • Electron Affinity – • Energy change when an electron is ADDED • When EASY to add an electron – EA is EXOTHERMIC / NEGATIVE • When DIFFICULT to add an electron – EA is ENDOTHERMIC / POSITIVE • Across a period – EA is easier/more exothermic • Down a group – EA is difficult/more endothermic FYI - Generally more difficult to add e- to larger atoms!!

20. Periodic Properties • Ionic Radius • Size of ion • Same trend as atomic radius: • Across a period – gets smaller • Down a group – gets bigger

21. Periodic Properties Potassium Atom Potassium ION • Ionic Radius • Size of ion • Cation – Lost electrons • Positively charged ion • Smaller than neutral atom; due to less electrons, so nucleus can pull better on each e-

22. Periodic Properties • Ionic Radius • Size of ion • Anion – Gained electrons • Negatively charged ion • Larger than neutral atom; due to more electrons, so nucleus can’t pull as well on each e-

23. Periodic Properties • Electronegativity • Ability to attract electrons • Across a period – EN increases • Down a group – EN decreases FYI: • Nonmetals are always more electronegative!! • Larger atoms attract e- less strongly

24. Example Questions Which is smaller – C or O? Which is larger – Be or Be+2 (Neutral Be atom or Be ion)? Which has a more exothermic electron affinity – Na or P? Which has a more endothermic electron affinity – K or Cs? Which has a higher ionization energy – Ga or Se? Which has a higher electronegativity – F or Br?