1. 1. Elements in the same row belong to the
same
.
period
2. Elements in the same column are
group
members of the same
.
3. Elements that have many similar
properties belong to the same group .
4. Generally, the atomic mass of elements
increases
as you move from left to
right and from top to bottom on the
Periodic Table.

2. Review
Periodic table
Groups
18
Elements in each group have similar
properties
Periods
7 periods

3. Electron Configuration
Electrons orbit around the
nucleus
Form a “cloud” around the
nucleus
The “cloud” has “layers”
“Layers” = energy shells

4. Energy Levels
 Labeled with capital letters
 “K” first shell
 Closest to the nucleus

5. Energy Levels
 Holds up to 2 electrons
 “L” shell is the second
 Holds up to 8 electrons

6. Energy Levels
“M” shell is next
Holds up to 18
electrons
There are more than 3
shells

7. Energy Levels
 No. of shells depends on
the no. of electrons
 Each shell must be full
before a new one forms

8. Valence Electron(s)
Electron(s) in the outer most
shell of an atom
The group number tells you
the number of valence
electron(s)

9. Valence Electron(s)
Group 1, 1 valence
electron
Group 13?
3
Determines an elements
reactivity

10. Valence Electron(s)
The period tells you how
many energy shells an atom
has
And which shell the valence
electron(s) are in

11. Octet Rule
Elements need 8
valence electrons to be
stable
Or their outer shell is
full

12. Argon Atom
8 valence electrons = stable
Outer shell is full = stable