Chem Chapter 2

Lewis Structure

A diagram showing atom bonds and electron placement.

VSEPR Theory

VSEPR theory predicts shapes based on electron repulsion

Covalent Bond

A covalent bond is formed when two non-metals share electrons.

Intramolecular Forces

Forces that hold atoms together within a molecule (e.g., covalent bonds).

Intermolecular Forces

Forces that occur between molecules, including dipole-dipole, dispersion forces, and hydrogen bonding.

Polar Molecule

A molecule with an asymmetrical shape that results in a permanent dipole moment.

Non-Polar Molecule

A molecule with a symmetrical shape, resulting in an even distribution of charge.

Dipole-Dipole Forces

Attractive forces between the positive end of one polar molecule and the negative end of another.

Hydrogen Bonding

A special type of dipole-dipole attraction that occurs when hydrogen is covalently bonded to nitrogen, oxygen, or fluorine.

Diamond

An allotrope of carbon that has a 3D tetrahedral lattice structure, is hard, and does not conduct electricity.

Graphite

An allotrope of carbon composed of layers of hexagonal lattices, conducts electricity due to delocalised electrons.

Amorphous Carbon

Carbon that lacks a crystalline structure and has no ordered arrangement of atoms.

Melting Point

The temperature at which a solid becomes a liquid, influenced by intermolecular forces.

Boiling Point

The temperature at which a liquid becomes a gas, strongly affected by the strength of intermolecular forces.

Dispersion Forces

Weak forces arising from temporary shifts in electron density in non-polar molecules, leading to temporary dipoles.

Permanent Dipole

A permanent separation of charge within a polar molecule due to asymmetrical arrangement of polar bonds.

Lone Pair

A pair of valence electrons not involved in bonding, which influences the shape of molecules.

Tetrahedral Shape

A molecular shape formed by four pairs of bonded electrons around a central atom, leading to a three-dimensional arrangement.

Pyramidal Shape

A molecular shape that occurs when there is one lone pair and three bonded pairs around a central atom.

Bent Shape

A molecular shape resulting from two bonded atoms and two lone pairs around a central atom.

Structural Formula

A representation of a molecule that shows the arrangement of atoms and the bonds between them.

Molecular Formula

A notation that uses elemental symbols and subscripts to represent the number of atoms in a molecule.

Allotropes

Different structural forms of the same element, such as diamond and graphite for carbon.