The Periodic Table
The Periodic Table
is a chart that organizes all the
elements in a way that shows patterns –
both similarities and differences among
the elements.
Elements are listed by increasing
atomic number.
The horizontal rows are called periods.
There are 7 periods.
The vertical columns are called groups.
There are 18 groups.

Elements in the same group have similar
chemical properties.
Periods


Each period
corresponds to the
energy levels found
outside an atoms
nucleus
The period that an
element is located in
tells you what the
highest energy level is
that will contain
electrons
Periods
The most energy levels found in an atom (currently)
is seven which corresponds to the seven periods in
the table
Example
 Potassium (K) is located in period 4 and thus will
have its valence electrons in the fourth energy
level
Group
1
Period 1
Group
2
Period 2
Period 3
Period 7
3 4 5
18
Special Groups
Group 1 elements are known as the alkali
metals.
Group 2 elements are known as the alkaline
earth metals.
Group 17 elements are called halogens.
Group 18 elements are called noble gases.
Groups 3-12 are called transition metals.
The Lanthanides and Actinides are the
excerpts at the bottom.
Group 1 – Alkali Metals
Have only one e- in the
valence shell
Most reactive of all metals
– reactivity increases as
you go down the group
Hydrogen is an exception!

Has one valence electron
but is classified as a nonmetal
Group 2 – Alkaline Earth
Metals
Has two e- in valence shell
Become increasingly soluble with
increase in temperature
Group 18 – Noble Gases
Generally are chemically inert meaning they
do not react with other elements
This is because they already have 8e- in their
valence shell causing them to be stable
(He only has 2 valence e-)
Only He and Ne are truly inert – others will
react in limited amounts under specific
conditions
Group 17 – Halogens
Halogen means “salt former” – form salts
when reacting with a metal
Most exist as diatomic molecules in gaseous
state
Ex. Cl2
All are one e- short of a full valence shell
causing them to be very reactive
Are non-metals
Transition and Rare Earth Metals
Some of the rest of the elements in the periodic
table fall under these two categories
 Transition metals are groups 3 – 12
 Rare earth (inner transition) metals are broken
down further into actinides and lanthanides
Transition and Rare Earth Metals
These are also called the inner
transition elements and they
belong here
Representative Elements
Groups 1, 2 (s block) and 13-18 (p
block) are often called representative
elements. They are sometimes labelled
1A, 2A, 3A, …8A
 These elements are called the
representative elements
1A
2A
3A 4A 5A 6A 7A
8A
0
The Periodic Table
There are 3 major sections of elements
in the periodic table:
1.
2.
3.
Metals
Non-metals
Metalloids
Metals are located to the left of the
“staircase line” and non-metals are to
the right (except H). Metalloids border
the line.
Properties of Metals
Physical Properties
Chemical Properties:
Luster (shiny)
 Good conductors
 High density
 High melting point
 Malleable/bendable
 Solid at room
temperature
(except Hg)


Easily lose electrons
 Corrode easily (ex:
rusting or tarnishing)
 Low electronegativity
Properties of Non-metals
Physical Properties:





•
Dull
Poor conductor
Brittle
Not malleable
Low density and melting point
Chemical Property:


Tend to gain electrons
High electronegativity
Properties of Metalloids
Metalloids border the “staircase” and tend to
have some properties of both metals and
non-metals.
solids
can lose or gain electrons
semi-conductors of electricity (Conduct heat
and electricity better than non metal but not
as well as metals
Shiny or dull
Malleable
The Periodic Table