Across the periodic table, there are two important changes: atomic radius and ionization energy. Let’s break these down.

Atomic Radius

• Trend: The atomic radius gets smaller as you move from left to right across a row.
• Why It Happens: As you go from one element to the next, the number of protons in the nucleus increases. This stronger pull from the nucleus brings electrons closer to it.

Example: If we look at sodium (Na) and chlorine (Cl), sodium has a bigger atomic radius because it has fewer protons pulling on its electrons.

Ionization Energy

• Trend: Ionization energy increases as you go from left to right across a row.
• Why It Happens: The stronger attraction between the electrons and the nucleus means that it’s harder to take away an electron from the atom.

Example: It’s much easier to remove an electron from lithium (Li) than from fluorine (F).

Knowing these trends helps us understand how different elements act in chemical reactions!