Question

1. what affects the atomic radius of an atom? (0:45)
2. why does the atomic radius change as you move down a group (from hydrogen, to lithium, to sodium, and so on?) (1:23 - 1:56)
3. compare the atomic structures of lithium and beryllium. how does the addition of a proton in beryllium influence its atomic radius? (2:10 - 3:20)
4. what trends can be observed in atomic radii throughout the periodic table based on the examples provided in the video? (3:25 - 3:32)

Explanation:

1. The number of electron shells and the effective nuclear charge affect atomic radius. More electron - shells increase radius, while a higher effective nuclear charge decreases it.
2. As you move down a group, the number of electron shells increases. Each new shell is farther from the nucleus, causing the atomic radius to increase.
3. Beryllium has one more proton than lithium. The increased positive charge in beryllium's nucleus attracts the electrons more strongly, pulling them in closer and making the atomic radius of beryllium smaller than that of lithium.
4. Atomic radius generally decreases across a period (due to increasing effective nuclear charge) and increases down a group (due to adding electron shells).

Answer:

1. The number of electron shells and effective nuclear charge.
2. The number of electron shells increases, making the atom larger.
3. The additional proton in beryllium attracts electrons more strongly, reducing the atomic radius compared to lithium.
4. Decreases across a period, increases down a group.