The Periodicities of the Periodic Table

Ionization energy energy needed to make an ion by losing electrons

First Ionization Energy Definition: energy needed to remove the most loosely held e- Valence electron high E electron Outermost electron

1st

Why 1st? Is there a 2nd? 2nd ionization energy 3rd ionization energy Energy needed to remove the second electron 3rd ionization energy Energy needed to remove the third electron

1st 3rd e- removed 2nd e- removed

What’s holding the e- in place? PROTONS “Opposites attract” There is a force of attraction between protons (+) and electrons (-)

Ionization E trend? 3 p+ 9 p+ As move across a period…IE increases. WHY? 3 p+ 9 p+

As you go across a period a proton and an electron are being added more p+ hold the e- tighter when in the same energy level Increasing nuclear charge

More E to remove As move UP a group … IE increases. WHY? Period 1 Let’s figure it out . . . More E to remove

Potassium 19 p+

Sodium 11 p+

Lithium 3 p+

because . . . As you go up a group INCREASES because . . . As you go up a group the electron shells get closer to the nucleus and can hold on to the e- tighter. ALSO………………….

Potassium 19 p+

SHIELDING as you go DOWN a group Not only does the distance increase between the p+ and valence e- e- in outer shells repel each other & makes them easier to remove

Who has the highest IEs? Lowest?

Electronegativity E-neg

Electronegativity Ability of an atom to attract electrons of other atoms. In other words. . . Atoms with high e-neg are bullies that steal electrons

F Electronegativity INCREASES EXCEPT for Noble gases. WHY? Periodic trend F INCREASES EXCEPT for Noble gases. WHY? Already have full valence shell!

Summary Atoms with high electronegativities also have high ionization E

Atomic Radius Radius distance from the center of a circle (Nucleus) to the outermost edge (valence shell) R

Atomic Radius Periodicity DECREASES DECREASES

Why????? Why does atomic radius DECREASE as you move up a group? Losing full Energy levels Why does atomic radius DECREASE as you move across a period? Increasing the # of p+ holds the e- in tighter

NOW Compare the radii of Na0 and Na+ POSITIVE Ionic radius is smaller the radii of Cl0 and Cl- NEGATIVE Ionic radius is larger

Compare 2 different elements Compare the ionic radius of Mg2+ and the atomic radius of Ne. The ionic radius of Mg2+ is smaller than the atomic radius of Ne because the Mg 2+ ion has more p+ (12) than the Ne atom (10).

General Formulas of compounds You can look at the groups on the periodic table and determine how they will combine with elements of different groups.

Group 1 Group 2 Group16 Group 17 +1 +2 -2 -1 1:1 General Formula: AB

Group 1 Group 2 Group16 Group 17 +1 +2 -2 -1 1:1 General Formula: AB

Group 1 Group 2 Group16 Group 17 +1 +2 -2 -1 2:1 General Formula: A2B

Group 1 Group 2 Group16 Group 17 +1 +2 -2 -1 1:2 General Formula: AB2

THE END