periodic trends

Which group is very reactive with water and forms ionic compounds?

⚡ Alkali metals (Group 1); low ionization energy 💧

Which metals have low ionization energy and reactivity with water increases down the group?

🟢 Alkaline earth metals (Group 2); reactivity ↑ down group 💦

Which group has high electronegativity, is highly reactive with metals, and is a strong oxidizer?

🟡 Halogens (Group 17); Cl has highest electronegativity ⚡

Which elements are inert and non-reactive?

✨ Noble gases (Group 18); stable, generally non-reactive

Which metals often show bright colors and form colored ions/compounds?

🌈 Transition metals; often form colored ions/compounds

How do you calculate bond length?

🔗 Bond length ≈ atomic radius × 2

What is the trend of atomic radius across a period and down a group?

⬇ across period, ⬆ down group

What is Z-effective?

🧲 Effective nuclear charge; proton “pull” on electrons → more protons = smaller atom

What happens to an atom when it gains an electron?

➕ Atom becomes larger (same element)

What is ionization energy (IE)?

⚡ Energy required to remove an electron; opposite trend of atomic radius

What are the exceptions to ionization energy trends?

❗ N > O (half-filled p orbital stable), Be > B (full s orbital stable)

What is electronegativity?

💧 Atom’s “thirst” for electrons → ↑ across period, ↓ down group

What is electron affinity (EA)?

💖 Energy change when atom gains an electron; more negative = favorable; ↑ across period, ↓ down group; F > Cl; exceptions: Be & N; noble gases excluded

What is the trend of atomic radius?

⬇ across period, ⬆ down group

What is the trend of ionization energy / EN / EA?

⬆ across period, ⬇ down group

What is the trend of metal reactivity?

⚡ ↑ down group

What is the trend of nonmetal reactivity?

🌿 ↑ across period