Transcript Week 6 Periodicity

Periodic Trends
(a.k.a. “Periodicity”)
Properties of atoms that can be
predicted by patterns on the periodic
table.
Atomic Radius
 the SIZE of an atom
from nucleus to outer
energy level
 More energy levels =
larger radius = larger
size
 Atoms on the left of
the table are bigger
because they have
lower
electronegativity
Atomic Radii for “A” Elements
Atomic Size Increase
Metallic Character
1
IA
1
18
VIIIA
2
IIA
13
IIIA
14
IVA
15
VA
16
VIA
17
VIIA
2
3
4
5
6
7
3
IIIB
4
IVB
5
VB
6
VIB
7
VIIB
8
9
VIIIB
10
Metals
11
IB
12
IIB
Nonmetals
Metallic Character
 Metals tend to give up electrons easily
 The more easily an atom give up
electrons, the more metallic character it
has
Metallic Character Trend
Electronegativity
 The ability of an atom to attract and hold
an extra electron
 How “greedy” an atom is for electrons
 Elements that are small with ALMOST full
valence shells are the most
electronegative
Electronegativity
Electronegativity Trend
Ionization Energy
 The energy needed to remove an electron
from an atom (a.k.a. to make the atom an
ion)
 More electronegative = harder to remove
an electron = higher ionization energy
Ionization Energy
Reactivity
 Determined by position on the table:
 Metals: most metallic character
 Non-metals: most electronegativity
Review Questions:
1) How do energy levels determine
size?
2) Which element probably has the
most metallic character?
3) Which is the largest?
4) Why does it take more energy to
remove an electron from F than it
does to remove an e- from Cs?
5) Pair up the trends according to
their similarity (look at arrows!).