Chemistry
Ionic vs covalent bonds — quick study summary
AP ChemistryGCSE ChemistryIB Chemistry
Atoms bond to achieve a stable (usually full) outer electron shell. Ionic bonds form when one atom transfers electrons to another, producing oppositely charged ions held together electrostatically. Covalent bonds form when atoms share electron pairs. Metals + non-metals usually form ionic; non-metals + non-metals form covalent.
Key points
- Ionic: electron transfer between metal and non-metal (e.g. NaCl)
- Covalent: electron sharing between non-metals (e.g. H₂O, CO₂)
- Ionic compounds: high melting/boiling points, conduct when molten or dissolved
- Covalent compounds: lower melting points (usually), don't conduct electricity
- Polar covalent: unequal sharing (electronegativity difference 0.4–1.7)
Practice quiz
Click each question to reveal the answer.
1. What type of bond holds Na⁺ and Cl⁻ together in salt?
- Covalent
- Ionic
- Hydrogen
- Metallic
Answer: Ionic
2. What type of bond is in a water molecule (H₂O)?
Answer: Covalent (polar)
3. Which compound has a higher melting point — NaCl or H₂O?
Answer: NaCl
Ionic lattices require breaking many strong electrostatic bonds.
Last reviewed: May 2026