Question

1. collect data: use the ruler to measure the atomic radii of the group 1 elements. as you do so, count the energy levels (shown as rings of electrons) in each atom. record in the table.

element	h	li	na	k	rb	cs
atomic radius (pm)	1	2	3	4	5	6

1. observe: what happens to the radius as you move down group 1?

1. explore: turn off show ruler. select li, and then select be. observe the radii of the elements in group 2. then look at other groups. what pattern do you see?

1. draw a conclusion: in general, what is the effect of the number of energy levels on the radius of an atom?

1. predict: how do you think the radius of an atom will change as you move across a period (horizontal row) in the periodic table?

Explanation:

Step1: Analyze group - 1 trend

As we move down group 1, the number of energy levels increases. From H to Cs, the number of energy levels goes from 1 to 6 and the atomic radius also increases. This is because each new energy level is farther from the nucleus, increasing the atomic radius.

Step2: Observe group - 2 and other groups

For elements in the same group, as the number of energy levels increases (going down the group), the atomic radius increases. This pattern is consistent across different groups.

Step3: Determine the effect of energy - levels on atomic radius

The more energy levels an atom has, the larger its atomic radius. This is because additional energy levels mean electrons are located farther from the nucleus.

Step4: Predict across a period

As we move across a period (from left to right), the number of protons in the nucleus increases, pulling the electrons closer. So, the atomic radius generally decreases across a period.

Answer:

1. The atomic radius increases.
2. For elements in the same group, as the number of energy levels increases, the atomic radius increases.
3. The more energy levels an atom has, the larger its atomic radius.
4. The atomic radius generally decreases as you move across a period.