Periodic Trends

Multiple Choice

Which is a larger atom, lithium or chlorine?

• Oxygen
• Lithium
• Chlorine
• Hydrogen

Multiple Choice

Which is larger, arsenic or sulfur?

• Arsenic
• Oxygen
• Carbon
• Sulfur

Multiple Choice

Which atom is more electronegative, sodium or oxygen?

• sodium
• hydrogen
• carbon
• oxygen

Ionization Energy

• Definition: Ionization energy is the amount of energy required to remove an electron from an atom in its gaseous state.

• Trend Across a Period: Increases as you move from left to right across a period due to stronger nuclear attraction, making it harder to remove an electron.

• Trend Down a Group: Decreases as you move down a group because outer electrons are farther from the nucleus and more shielded, requiring less energy to remove.

• Significance: Indicates how tightly an atom holds onto its electrons, affecting reactivity—higher ionization energy means less reactivity for metals and more reactivity for non-metals.

​Summary