Chemical Bonding
Ionic, covalent and metallic bonding
Why Do Atoms Bond?
Atoms bond to become more stable by achieving a full outer electron shell (octet rule — 8 electrons, or 2 for the first shell). They do this by transferring or sharing electrons with other atoms.
Types of Chemical Bonds
• Ionic bonding: a metal transfers electrons to a non-metal (e.g. NaCl — Na gives 1 electron to Cl). Results in charged ions that attract each other.
• Covalent bonding: two non-metals share electron pairs (e.g. H₂O — oxygen shares electrons with two hydrogen atoms).
• Metallic bonding: metal atoms share a 'sea' of delocalised electrons (e.g. copper wire).
Example
Lewis Dot Diagrams
NaCl:
Na (2.8.1) → loses 1e⁻ → Na⁺ (2.8)
Cl (2.8.7) → gains 1e⁻ → Cl⁻ (2.8.8)
Electrostatic attraction between Na⁺ and Cl⁻ forms the ionic bond.
H₂O:
O has 6 valence electrons, needs 2 more.
Each H has 1 valence electron, needs 1 more.
O shares one pair with each H → two covalent bonds.
Note
Properties Comparison
Ionic compounds: high melting points, conduct electricity when dissolved or molten, crystalline solids.
Covalent compounds: low melting points, poor electrical conductors, can be gases/liquids/soft solids.
Metals: good conductors, malleable, lustrous.
Key Vocabulary
Ionic bondA bond formed by the transfer of electrons from a metal to a non-metal
Covalent bondA bond formed by sharing electron pairs between non-metals
Metallic bondA bond formed by delocalised electrons shared among metal atoms
IonAn atom that has gained or lost electrons and has a charge
Octet ruleAtoms tend to bond to achieve 8 electrons in the outer shell
SASL Avatar
Loading avatar...
1 / 5
Ionic bond
Speed: