Periodic Trends Worksheet 1 Answer Key Using the Periodic Law

If you’re looking to understand how the properties of elements change across the table, start by focusing on atomic radius, ionization energy, and electron affinity. These are the fundamental aspects that will give you the best insight into the reactivity and other characteristics of elements as you move from one group to another.

Atomic radius decreases as you move from left to right within a period. This happens because of the increased positive charge in the nucleus, which pulls electrons closer. On the other hand, as you move down a group, the atomic radius increases due to the addition of electron shells, which outweigh the effect of nuclear charge.

Ionization energy follows a similar pattern. It increases across a period as the effective nuclear charge grows, making it harder to remove an electron. Conversely, it decreases as you go down a group because the outermost electrons are further from the nucleus and are more easily removed.

Finally, electron affinity–the tendency of an atom to accept an electron–generally becomes more negative as you move across a period. This means elements become more likely to gain electrons. However, as you move down a group, electron affinity becomes less negative due to the increasing distance between the nucleus and the incoming electron.

By focusing on these patterns, you’ll better understand how elements behave in different conditions and how their positions on the table correlate with their physical and chemical properties.