Atoms with more than one electron

WDYT?WDYT?

•What are they pulling off the atoms?

•Compare the size of the atoms and the difficulty the men are having.

Chp1 Act 6 Page 46

Investigation

• Based on the “what do you see?” write a definition for ionization energy.

Periodicity of first ionization energy (IE1)

Using Two different color pens/markers, highlight Group I and Group 18 elements on the bottom graph

Ionization energy

• Energy required to overcome the attraction of the nuclear charge and remove an electron.

• What family is Helium in on the PT?

• What family is Lithium in on the PT?

• Which one has the greater IE? Why?

Ionization Energy

What is the IE trend as you go down a group?

What is the IE trend as you go across a period from left to right?

First Ionization Energy

Lithium (Z=3)

Sodium (Z=11)

Hydrogen (Z=1)

+ e-

++

+

e-

8e-

2e-

++++

e-

+

e-H+

++

+

e- 2e-

Li+

e-

8e-

2e-

++++

Na+

First Ionization Energy

++

+

e-

Lithium (Z=3)

8e-

Sodium (Z=11)

2e-

2e-

++++

e-

+

Hydrogen (Z=1)

e-

D

ecre

asin

g

Lithium (Z=3)3 protons screened

by 2 e-

++

+

e-

2e-

Beryllium (Z=4)4 protons screened

by 2 e-

Boron (Z=5) 5 protons screened

by 2 e-

++

+

e- 2e- e-

+ ++

+

e- 2e-e-

e-

++

1 e- removed = 2s0 1 e- removed = 2s1 1 e- removed = 2s22p0

D

ecre

asin

g Decreasing

Lithium (Z=3)3 protons screened

by 2 e-

++

+

e-

2e-

Beryllium (Z=4)4 protons screened

by 2 e-

Boron (Z=5) 5 protons screened

by 2 e-

++

+

e-

2e- e-

+ ++

+

e- 2e-e-

e-

++

D

ecre

asin

g Decreasing

Ionization energy

• Second ionization energy IE2 – to remove 2nd e-– Always larger than IE1

– as e- are removed, Z remains constant and remaining e- are harder to remove

IE Periodic Table TrendsChem Saver p 22

SAMPLE PROBLEM 8.4 Ranking Elements by First Ionization Energy

PLAN:

SOLUTION:

PROBLEM: Using the periodic table only, rank the elements in each of the following sets in order of decreasing IE1:

(a) Kr, He, Ar (b) Sb, Te, Sn (c) K, Ca, Rb (d) I, Xe, Cs

IE decreases as you proceed down in a group; IE increases as you go across a period.

(a) He > Ar > Kr

(b) Te > Sb > Sn

(c) Ca > K > Rb

(d) Xe > I > Cs

Group 8A(18) - IE decreases down a group.

Period 5 elements - IE increases across a period.

Ca is to the right of K; Rb is below K.

I is to the left of Xe; Cs is further to the left and down one period.