Atomic radius is the distance from the atom's nucleus to the outer edge of the electron cloud. This shows us the size of the atom.

​

Radius of an Atom

What are the sizes of the atoms on the periodic table?

The Periodic Table is separated into GROUPS and PERIODS

Groups are vertical Columns on the Periodic Table. They run from top to bottom (Longways)

​

GROUPS

Groupss are labeled on the top of your reference tables (Groups 1 - 18).

​

GROUPSS

The group number tell you the number of valence electrons

​

Elements in the same group or column has simlar properties

​

Periods are horizontal rows on the periodic Table. They run from left to right (across)

​

PERIODS

Periods are labeled on the sides of your reference tables (Periods 1 - 7).

​

PERIODS

The PERIOD NUMBER tells you the number of energy levels

​

How does atomic radius change throughout the periodic table?

The Atomic Radius increases down a group and decreases accross a period

​

Atomic Radius on the Periodic Table

​Take a close look at how the atomic radius changes across a period and down a group

We add an energy level as move down a group. The atom gets larger

We add more protons to the nucleus as we move across a period. A bigger positive pull from the nucleus makes the atom tighter and smaller

Moving down group 2 - atoms get bigger
A28Moving down group 2 - atoms get biggerAlways count energy levels to see which atom is bigger

lways count energy levels to see which atom is bigger

Use pages 10 -11 to find the radius of the atom and compare to see which is bigger or smaller