Transcript Atomic Trends: Atomic Size

Atomic Trends: Atomic Size
Small
n=1
Increasing
“n”
n=2
n=3
n=4
n=5
Larger
orbitals
n=6
n=7
Large
Large
Small
n is constant...
Additional electrons placed in the same orbital
Atomic size shouldn’t change!
But Z (nuclear charge) is increasing (left to right).
There is an increasing attraction for all electrons!
Atomic size decreases!
Atomic Trends: Ionization Energies
Definitions:
1st Ionization Energy (I.E.1)
The energy required to remove the first
electron from a neutral atom (kJ/mole).
2nd Ionization Energy (I.E.2)
The energy required to remove the second
electron from the same atom (kJ/mole).
+
Remove 1eCosts YOU the I.E.1
2+
Remove 1eCosts YOU the I.E.2
Which electron was the most difficult to remove???
Atomic Trends: Ionization Energies
Which electron was the most difficult to remove???
To remove the first electron, you separate an electron from it’s atom.
To remove the second electron, you separate an electron from an ion.
I.E.1 < I.E.2
Atomic Trends: Ionization Energies
Electrons
Close to
Nucleus
Difficult to
remove eLarge I.E.
Electrons
Far From
Nucleus
Easier to
remove eSmall I.E.
Small
Electrons
Close to
Nucleus
Large
Small Difficult to
remove eLarge I.E.
Atomic Trends
Size oxygen <
Large I.E.
Small
atoms
I.E. oxygen >
Size phosphorus
I.E. phosphorus
O
P
Large
atoms
Small I.E.
Small
atoms
Large I.E.
Atomic Trends: Ionization Energies
Full orbital
1s2 ...difficult to remove e
...higher I.E.
He
Higher I.E.
e- is difficult to remove
1s2 2s2 2p6
Full orbital (High I.E.)
½ full (higher I.E.)
1s2 2s2 2p5
1s2 2s2 2p3
H
Lower I.E.
e- is easier to remove
1s1
1s2 2s2
1s2 2s2 2p1
1s2 2s2 2p4
1s2 2s2 2p2
Easier to remove 2p1 e- (Lower I.E.)
1s2 2s1
Partially full orbital
Easy to remove 2s1 electron (Low I.E.)
1
H
2
He
3
Li
4
5
6 7
Be B C N
Atomic Number
8
O
9
F
10
Ne
Atomic Trends: Ionization Energies
I.E.Ne < I.E. He
He1s
2
Why is Helium’s
I.E. greater than
Neon’s I.E.?
Ne
I.E. He
1s2 2s2 2p6
I.E. Ne
Because Ne is a
larger atom and its
electrons are more
loosely held!
1
H
2
He
3
Li
4
5
6 7
Be B C N
Atomic Number
8
O
9
F
10
Ne