Chemistry · Both
Ionic & Covalent Bonding
How ionic and covalent bonds form, and the properties of simple ionic and covalent substances.
Atoms bond to get a full outer shell. Metals and non-metals often form ionic bonds; non-metals with non-metals form covalent bonds.
Ionic bonding
Metal + non-metal → **ionic bond**
• Metal atoms **lose** electrons → positive ions
• Non-metal atoms **gain** electrons → negative ions
• Opposite charges attract (electrostatic force)
Example: Sodium (2,8,1) loses 1 electron → Na⁺
Chlorine (2,8,7) gains 1 electron → Cl⁻
Form NaCl (giant ionic lattice)
**Properties of ionic compounds:**
• High melting/boiling points
• Conduct electricity when molten or dissolved (not as solids)
• Often soluble in water
Covalent bonding
Non-metal + non-metal → **covalent bond**
Atoms **share** pairs of electrons so each gets a full outer shell.
Examples: H₂, O₂, H₂O, CO₂, CH₄
**Simple molecular substances:**
• Low melting/boiling points (weak forces between molecules)
• Do not conduct electricity
• Often gases or liquids at room temperature
Worked example
What type of bonding is in water (H₂O)?
Solution
**Covalent** (non-metal + non-metal, sharing electrons).
Practice questions
Try these without looking at the answers first.
Q1.Ionic or covalent: sodium chloride?
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Ionic
Q2.Ionic or covalent: carbon dioxide?
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Covalent
Q3.Why do ionic compounds conduct when molten?
Show answer
Ions are free to move