# Question #2fc5b

##### 1 Answer

You can do it like this:

#### Explanation:

The effective nuclear charge

Where

We can calculate

Electrons are grouped together in increasing order of

You can calculate the screening constant as follows:

Add 0.35 for each other electron within the same group, except for

If the group is of the

For

Lets apply this to

The electron structure is:

For a 3d electron:

Within the 3d group there are 4 other electrons giving 4 x 0.35 = 1.40 units.

There are 18 other electrons closer to the nucleus giving 18 x 1.00 =18.0 units.

For a 4s electron:

Within the 4s group there is 1 other electron giving 1 x 0.35 = 0.35 units.

In the (n - 1) group, which are the 3s, 3p and 3d, electrons there are 13 electrons giving 13 x 0.85 = 11.05 units

This leaves 10 (n - 2) electrons. This gives 10 x 1 = 10 units.

This shows that the 4s electrons experience a smaller effective nuclear charge than the 3d electrons so are more easily lost

This is consistent with observations.