1. How are atomic radii and ionization energy related (i. e. as atomic radius increases, what happens to the ionization energy) ?

2. Generally, as you go from left to right across a period on the periodic table, what happens to atomic radius? What about IE?

3. Generally, as you go down a group in the periodic table, what happens to atomic radius and IE?

4. Why does radius increase as you go down a group (hint: think of B-R diagrams) ? Why would an increase in radius make it easier to lose an outer electron (i. e. give a lower ionization energy) ?

1) Atomic radii and ionization energy related in this way: when we move from left to right across the periodic table, the atomic radii of elements becomes smaller. Having a smaller radius, the electrons are placed very tightly to the nucleus than larger atoms. So, the ionization energy that is required to withdraw an electron would be greater in regard to the smaller atoms.

2) As you go from left to right across a period on the periodic table the atomic the radius tend to decrease. Keep in mind that atomic radius always decreases from left to right within a period. It happens because the number of protons and electrons across a period are increased.

3) Generally, as you go down a group in the periodic table, the atomic radius increases. Remember that when you move down a group in the periodic table, the number of filled electrons increases.

4) The radius increases as you go down a group because of electron shielding. And, the main cause is that number of protons and electrons across a period. Take into account that atomic radius increases from top to bottom within a group.

5) An increase in radius will make it easier to lose an outer electron because it is placed farther from the nucleus. To be more precise, the increased distance becomes weaker the force of attraction. Then there usually occurs the effect called 'screening', during which the electrons from inner electron shells block some of the charge.