Question

question 3. the atomic radius of elements

as you move down a group
in the periodic table. for example, the atomic
radius of barium (ba) is

than the
atomic radius of calcium (ca). similarly, the
atomic radius

as you move
across a period from left to right. for instance,
the atomic radius of lithium (li) is

than the atomic radius of oxygen
(o).

Explanation:

Step1: Analyze group trend (atomic radius down a group)

In the periodic table, as you move down a group, the number of electron shells increases. Each new shell is further from the nucleus, so atomic radius increases. So the first blank (trend down group) is "increases". Barium (Ba) is below Calcium (Ca) in Group 2, so Ba's radius is "larger" than Ca's.

Step2: Analyze period trend (atomic radius across a period)

As you move across a period from left to right, the number of protons (nuclear charge) increases while the number of electron shells remains the same. The increased nuclear charge pulls electrons closer, so atomic radius decreases. Lithium (Li) is to the left of Oxygen (O) in Period 2, so Li's radius is "larger" than O's, and the trend across a period is "decreases".

Answer:

First blank: increases; Second blank: larger; Third blank: decreases; Fourth blank: larger