Ionic vs covalent bonding
The difference between ionic and covalent bonds and the properties they give.
Ionic bonding
Happens between a metal and a non-metal. The metal atom loses electrons to become a positive ion and the non-metal gains them to become a negative ion. The oppositely charged ions attract strongly in a giant lattice.
Covalent bonding
Happens between non-metals. Atoms share pairs of electrons. This makes small molecules (like H₂O) or giant covalent structures (like diamond).
Properties
Ionic compounds have high melting points and conduct electricity when melted or dissolved, because the ions can move. Simple covalent molecules have low melting points and don't conduct, because the forces between molecules are weak.
✏️ Worked example
Why does sodium chloride conduct when dissolved but not as a solid?
In the solid the ions are fixed in the lattice. When dissolved, the ions are free to move and carry charge.
🧠 Test yourself
What type of bonding is in CO₂?
Covalent (two non-metals).
What charge does a magnesium ion have?
2+ (it loses 2 electrons).
Why does diamond have a very high melting point?
Many strong covalent bonds must be broken in its giant structure.
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