Periodic Trends and Ionization Energy

Vocabulary flashcards reviewing periodic trends including atomic radius, effective nuclear charge, ionization energy, and ion formation.

Atomic Radius Trend (Down a Group)

Going down the periodic table, the atomic radius increases because there are more energy levels and increased $e^-$ shielding.

Atomic Radius Trend (Across a Period)

Going right across the periodic table, the atomic radius gets smaller because of an increased proton number and higher effective nuclear charge ($Z_{eff}$), which pulls in $e^-$ more tightly.

Effective Nuclear Charge ($Z_{eff}$)

The effective positive charge exerted by the nucleus that increases with proton number across a period, pulling $e^-$ more tightly toward the nucleus.

Ionization Energy

The energy required to remove an $e^-$ from an atom.

Ionization Energy Trend (Across a Period)

Going right across the periodic table, ionization energy increases because atoms get closer to a full valence (making it harder to remove an $e^-$) and experience an increased proton number (increased $Z_{eff}$) that attracts $e^-$ more.

Ionization Energy Trend (Down a Group)

Going down the periodic table, ionization energy decreases because $e^-$ are further away from the nucleus (more energy levels and more $e^-$ shielding), making $e^-$ less attracted to the nucleus and easier to remove.

Ion

A charged species formed when an atom adds or removes $e^-$.

Cation

A positively charged ion formed when an atom loses or has an $e^-$ removed.

Anion

A negatively charged ion formed when an atom adds or gains an $e^-$.