Lecture Periodic Table

Tom Lehrer periodic table song:http://www.youtube.com/watch?v=SmwlzwGMMwc

Tell me something you did not know about the periodic table before your reading.

What is something you thought was cool/unique about it?

What is periodic?

What is periodic about the table?

1. Developed in the 1870’s by Mendeleyev with an increasing atomic # (# protons).

Increasing Atomic mass would be incorrect, why?

because of the isotopes of atoms (different masses).

2. Organized and read like reading a book:

across and

down

-Arranged in periods (rows) by increasing atomic #

(what is at the end of a sentence ?)

-labeled by their period # ?

-each period indicates the number e- shells of the element

-what are the most # shells for any atom ?

-each period’s elements have the same # electron shells

A. Periodicity: the repeating pattern of the chart (called periodic)

is reflected in the different periods

1. shows a repeating pattern of chemical reactivity from period to period

-due to repeating:

valence e- # and

oxidation #

-ie: melting and boiling points:

both reflect strength of forces between their molecules:

strongest when valence shells are half empty (middle of periodic table)

2. diameter of atoms reduces across periods

3. energy needed to remove valence e- increases across periods

Non-periodic atomic number

3. Also arranged in groups (or families) (columns: like columns which hold up things: vertical). labeled by: 1) group #, or

2) oxidation #, or 3) element at the top

Elements in the same group have:A. similar characteristic properties: bp/fp/sp heatB. same # electrons in the valence shellC. same oxidation #: charge after octet rule applied

4. Zig-zag line between B-Al and Po-At separates metals (80% chart) on the left from non-metals on the right

5. The most reactive:A. metals: bottom left (Fr), easily gain or lose e-: thus

good electricity and heat conductorsB. non-metals: top right (F), e- held tightly,

tend not to lose e-: good electricity resistors

6. Far right (group 18) is the group of noble gases. These are inert, non reactive: because

the valence shell is full (oxidation # is 0)

7. Transition metals: middle of chart: groups Sc Zn, can have different oxidation #’s depending on the chemicals and environments they are reacting with

8. Some elements are synthetic: human made.

First is Tc (technetium: greek for artificial) and all elements > 92 (plus 61)

9. Halogens: Fluorine group: 17, very reactive due to -1 oxidation # (7 e- in valence shell):

combine w/ alkali metals to form salts

10. Alkali metals: Hydrogen group: 1, very reactive due to +1 oxidation # (1e- in the valence shell)

11. Alkaline earth metals (group 2): 2 e- in valence shell: very reactive

12. Metalloids: have properties of both metals and non-metals: along the zig-zag line

13. Decreasing atom size going to the right of each period:

increasing + charged nucleus pulls -e closer together (opposites attract)

Key point:

periodicity of the chart is due to a

repeating trend of oxidation numbers

toward a formation of a stable configuration

circular periodic tables: