Elements are the primary constituents of matter, which cannot be chemically broken down into simpler substances.

Atoms contain a positively charged, dense nucleus composed of protons and neutrons (nucleons).

When metal atoms lose electrons, they form positive ions called cations.

A covalent bond is formed by the electrostatic attraction between a shared pair of electrons and the positively charged nuclei.

The periodic table consists of periods, groups and blocks.

Organic compounds can be represented by different types of formulas.

Chemical reactions involve a transfer of energy between the system and the surroundings, while total energy is conserved.

Bond-breaking absorbs and bond-forming releases energy.

Chemical equations show the ratio of reactants and products in a reaction.

The rate of reaction is expressed as the change in concentration of a particular reactant/product per unit time.

Brønsted–Lowry acid is a proton donor and a Brønsted–Lowry base is a proton acceptor.

Oxidation and reduction can be described in terms of electron transfer, change in oxidation state, oxygen gain/loss or hydrogen loss/gain.