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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.