Which trend occurs as you move towards the bottom left of the periodic table?

As you move towards the bottom left of the periodic table, atomic radii tend to increase. This trend can be attributed to the addition of electron shells as you move down a group. Each successive element in a group has an additional electron shell, which results in a larger atomic size due to increased distance from the nucleus.

Additionally, as you move from left to right across a period, the effective nuclear charge increases due to an increase in protons, which pulls the electrons closer and decreases atomic radii. However, this effect is countered by the downward trend in atomic size as you gain more energy levels. Therefore, moving to the bottom left shows a clear increase in atomic radii, which is a definitive characteristic of elements in that region of the periodic table.

In contrast, ionization energy and electronegativity decrease in this direction. Similarly, electron affinity typically becomes less exothermic as you move towards the bottom left, as the ability to gain electrons is reduced due to the larger size and decreased effective nuclear charge felt by incoming electrons. Thus, atomic radii increasing is consistent with the observed behaviors of these other properties.