4.2 Covalent bonding

Define covalent bond.

A bond formed by the shared pair of electrons between two atoms.

What is a molecule?

A group of atoms held together by covalent bonds.

Define bond length.

The distance between the nuclei of two bonded atoms.

Define bond strength / bond enthalpy.

The energy required to break one mole of covalent bonds in the gaseous state.

How does bond length relate to bond strength?

Shorter bonds = stronger bonds.

Define single bond.

One shared pair of electrons.

Define double bond.

Two shared pairs of electrons.

Define triple bond.

Three shared pairs of electrons.

What is bond polarity?

The unequal sharing of electrons due to a difference in electronegativity.

Define electronegativity.

The ability of an atom to attract shared electrons in a covalent bond.

What is a polar covalent bond?

A covalent bond with unequal electron sharing.

What is a non-polar covalent bond?

A covalent bond with equal electron sharing.

Define coordinate (dative) covalent bond.

A covalent bond where both electrons come from one atom.

What is a giant covalent structure?

A lattice of atoms joined by strong covalent bonds throughout.

Give two examples of giant covalent structures.

Diamond and silicon dioxide (SiO₂).

Why do giant covalent structures have high melting points?

Because breaking the network of strong covalent bonds requires large amounts of energy.

What causes polarity in a covalent bond?

A difference in electronegativity between bonded atoms.

What is the relationship between polarity and dipole moment?

Greater electronegativity difference → greater dipole moment.