Question

1. the atomic radius is defined as the distance from the ____ to the ____ of the electron cloud.
2. atomic radius generally ______ as you move down a group on the periodic table.
3. atomic radius generally ______ as you move from left to right across a period.
4. the trend in atomic radius across a period is caused by an increasing number of ______ in the nucleus.
5. the trend in atomic radius down a group is caused by adding more ______

Explanation:

1. Atomic radius is the distance from nucleus to out - most part of electron cloud.
2. Down a group, new electron shells are added increasing atomic radius.
3. Across a period, effective nuclear charge increases pulling electrons closer, decreasing radius.
4. More protons in nucleus across a period cause stronger attraction on electrons.
5. Adding more electron shells down a group increases atomic radius.

Answer:

1. nucleus; outermost part
2. increases
3. decreases
4. protons
5. electron shells