Basic Concepts of Chemical Bonding

Sizes of Ions


Sizes of Ions

Sizes of ions influence:

The size of an ion is influenced by:

Cations

Cations are therefore smaller than the parent atom

Anions

Anions are therefore larger than the parent atom

For ions of the same charge (e.g. in the same group) the size increases as we go down a group in the periodic table

As the principle quantum increases the size of both the parent atom and the ion will increase

How does the nuclear charge affect ion size?

Consider the following collection of ions:

ion

electrons

protons

O2-

10

8

F-

10

9

Na+

10

11

Mg2+

10

12

Al3+

10

13

Each ion:

The radius of each ion decreases with an increase in nuclear charge:

Oxygen and fluorine precede neon and are nonmetals, sodium, magnesium and aluminum come after neon and are metals.


1996 Michael Blaber