Periodic trends help us understand how elements behave by showing us patterns in the periodic table. Let’s go over a few important trends:

1. Atomic Radius: This refers to how big an atom is. When you look down a group (which is a column in the table), the size of the atoms gets larger. For example, sodium ($Na$) is bigger than lithium ($Li$) because sodium has more layers of electrons.

2. Ionization Energy: This is the energy needed to take an electron away from an atom. Generally, this energy goes up as you move across a row in the table. For instance, it takes more energy to remove an electron from fluorine ($F$) than from lithium ($Li$) because fluorine has a stronger pull from its nucleus.

3. Electronegativity: This trend tells us how strongly an atom can attract electrons. Fluorine is the most electronegative element, which helps it form strong connections with other elements.

These trends help us make predictions about how elements will react, how they bond, and how they form compounds.