1. The Periodic Table
Chapter 5

2. 5.1 The periodic table
Dimitri Mendeleev - publish first real periodic table
Based on chemical and physical properties
Listed elements in increasing atomic mass order
Left spaces for undiscovered elements
His basic rule: the elements in any group, of the table are similar to their column-mates. Ex, look at the first column on the left, underneath hydrogen (H). The elements in this group are the alkali metals; they're all soft metals that react violently with water to make hydrogen gas.

3. …… Periodic Table aluminum Ga(1875) atomic mass 68 69.7
density
melting point low Co
oxide formula Al2O3 Ga2O3

4. ….. Periodic Table
Mendeleev formulated the original Periodic Law - Properties of elements are a periodic function of their atomic mass.
Mosely (English) discovers the proton so....new Periodic Law - Properties of elements are a periodic function of atomic number.
*** History lesson - After his brilliant discovery, Mosely was drafted into the infantry to fight for the crown in WW I. He was killed. Only after the war was it realized that scientists should probably not be drafted into combat roles. That policy exists to this day.***

5. 5.2 Electron configurations and the periodic table
*** valence e- have largest effect on chemical/physical properties
Label the groups/ families and periods

6. Names of Families Group 1 - Alkali Metals –
They are not found alone in nature - why? explosive with water - they are stored under kerosene - very reactive.
They react with nonmetals to form salts.
They are silvery, shiny (luster), have a low melting point, and are soft (so soft, you can cut them with a knife).
They are malleable (able to flattened into a sheet) and ductile (able to be drawn into a wire).
Sodium and Potassium are particularly important in body chemistry.

7. …..Families Group 2 - Alkaline Earth Metals -
2nd most reactive elements. Also not “lone state” elements.
Harder, denser than group 1. Common in sea salts.

8. …..Families Transition Metals - Groups 3-12.
Harder, more brittle, higher melting point than groups 1 and 2.
Form colored compounds.
Conduct heat and electricity well and are shiny.
Pd, Pt, Au - very unreactive (Noble metals).
They can't be divided neatly into groups; all of them have very similar properties.
Their valence electrons vary in chemical reactions. E.x. Iron (Fe), sometimes likes to give away 2e-, and sometimes 3e-.

9. …..Families Metalloids –
B, Si, As, Te, At, Ge, Sb - stairs and 2 people under the stairs.
Properties of metals and nonmetals.
Brittle - used in semiconductors, computers.

10. ….. Families Halogens - Group VII / 17 –
most reactive of the nonmetals.
Not found free in nature.
Solids, liquids, and gases in this group.
Widespread - sea salts, minerals, living tissue.
Many applications - bleach, photography, plastics, insecticides.

11. ….. Families Noble Gases - Group 18 –
Least reactive elements - used in air conditioners,
double pane windows, lights, balloons.

12. ….. Families Lanthanides - f block
rare earth elements (not really rare) - shiny, silver, reactive, make TV’s glow.
Some have very interesting properties. For example, gadolinium (Gd) is the only rare earth that's ferromagnetic--that is, it sticks to magnets, the way iron does.
Lanthanum is the only superconductor among them; at very low temperatures, it loses all resistance to the flow of electricity.

13. ….. Families Actinides - f block Side note -
unstable, radioactive - all but 4 are artificially created.
Side note -
f block elements are called inner transition elements - they were put into their current position by Glenn Seaborg - the only living person ever to have an element named after him.

14. 5.3 Electron Configuration and Periodic Properties
Periodic Trends:
For all of the following periodic trends you should:
know the definition
be able to draw the trend on periodic table drawings with arrows
explain why the trend happens
relate the trend to other trends
apply the trends on an “AB” sheet

15. Periodic Trends 2 trends
1. Atomic Radius - basic idea is “how big an atom is” - atoms are not spheres with outer boundaries due to the wave mechanical model.
2 trends
size - natural, logical - add more shells
size - not logical! why?
from left to right - more protons are added, but not more shells. Higher charged nucleus pulls electrons closer.

16. Periodic Trends
Atomic Radius
BIGGER

17. Periodic Trends Atomic Radius Examples Which has a larger radius?
Mg or Ca?
F or B?

18. Periodic Trends
2. Electronegativity- basic idea - the ability of an atom to attract electrons (Linus Pauling)
Electronegativity is related to atomic size…. They are opposites
Trend
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19. Periodic Trends Electronegativity Examples
Which has a larger electronegativity?
Cs or Mg?
Mn or F?

20. Periodic Trends Trend:
3. Ionization energy - energy required to remove the most loosely held electron from the outer energy level of an atom.
A(g) + energy yields A+(g) e-
Trend:
Larger
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21. Periodic Trends
IE is related to atomic radius - 2 reasons why smaller going down the table
1. greater distance from the nucleus - less attraction
2. inner electrons “shield” outer electrons from the nucleus
Examples
Which has a higher IE
Se or Cl?
B or Sr?

22. Periodic Trends Ionization Energy Cont’d
There is also a 2nd and 3rd IE - always higher than the first. IE of elements greatly increases when the outer shell has been emptied.
Example
Which has a higher 2nd IE, Na or Mg? Which has a higher 3rd IE - Al or Mg? Mg Na

23. Periodic Trends
4. Electron Affinity - energy absorbed when an electron is acquired by a neutral atom.
Basic idea - some atoms want to take on electrons - they have a high electron affinity value - they receive a lot of energy when accepting electrons
Trend:
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24. Periodic Trend Electron Affinity Cont’d Examples F or Na?
F = kJ/mole Na = -53 kJ/mole
F has a higher electron affinity - higher, more negative value

25. Periodic Trends
5. Valence electrons - outer shell electrons involved with bonding –tells you about an element’s chemical behavior +
Sodium
Chlorine
Salt

26. Periodic Trends Ions are created by gaining or losing electrons.
6. Ionic Radius - the size of an ion.
Ions are created by gaining or losing electrons.
Cation - positive, lost electrons
Metals tend to become cations
Anion - negative, gained electrons
Nonmetals tend to become anions
Cations are smaller than the neutral atom - why?
they lost a shell
Anions are larger - why?
more electron repulsion so shells are pushed farther apart

27. Periodic Trends Ionic Radius Cont’d Trend Example
Li+1 or Be Li is bigger because less protons pull the shell in less
O -2 or N N is bigger because less protons pull the shell in less
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28. Periodic Trends metals - larger atoms are more active - why?
7. Activity (Reactivity)
metals - larger atoms are more active - why?
they lose electrons more easily
nonmetals - smaller more active - why?
they gain electrons more easily

29. Periodic Table Metals Nonmetals Reactivity Trends Larger Larger Larger
Most active metals + most active nonmetals = most stable compounds
ex: RbF - very stable LiBr - less stable

30. Periodic Trends
8. Metallic character - some metals are said to be more metallic than others - really it is just a statement about their activity. If they are more active, they are said to be more metallic.
Trend
Which is more metallic?
Ca or Na?
Larger
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