CHEMISTRY PAPER 1 KEYWORDS

🔬 Atomic Structure and the Periodic Table

Element – A substance made of only one type of atom.

Compound – A substance made from two or more elements chemically bonded

. Mixture – Two or more substances not chemically bonded and easily separated.

Isotope – Atoms of the same element with the same number of protons but different numbers of neutrons.

Relative Atomic Mass (Ar) – The weighted average mass of an atom of an element compared to 1/12 the mass of carbon-12.

Atomic Number – The number of protons in the nucleus of an atom.

Mass Number – The total number of protons and neutrons in an atom's nucleus.

🧪 Bonding, Structure and Properties of Matter

Ionic Bonding – The electrostatic attraction between oppositely charged ions.

Covalent Bonding – A bond formed when two atoms share a pair of electrons.

Metallic Bonding – The attraction between positive metal ions and a sea of delocalised electrons.

Alloy – A mixture of metals or a metal and another element, designed to have improved properties.

Simple Molecular Substance – A substance made up of molecules containing a few atoms joined by covalent bonds.

Giant Covalent Structure – A large lattice of covalently bonded atoms (e.g., diamond or graphite).

Giant Ionic Lattice – A regular structure of ions held together by strong electrostatic forces.

🔥 Quantitative Chemistry

Mole – The amount of substance containing 6.02 × 10²³ particles (Avogadro’s constant).

Relative Formula Mass (Mr) – The sum of the relative atomic masses of all atoms in a formula.

Concentration – The amount of solute dissolved in a given volume of solution (mol/dm³).

Limiting Reactant – The reactant that is completely used up first, limiting the amount of product formed.

⚡ Chemical Changes

Reactivity Series – A list of elements ordered by their reactivity with water or acid.

Displacement Reaction – A reaction in which a more reactive element displaces a less reactive element from a compound.

Redox Reaction – A reaction involving both reduction (gain of electrons) and oxidation (loss of electrons).

Electrolysis – The breakdown of a substance using electricity.

Anode – The positive electrode where oxidation occurs.

Cathode – The negative electrode where reduction occurs.

Ore – A rock containing enough metal to make it economically worthwhile to extract.

💧 Energy Changes

Exothermic Reaction – A reaction that releases energy to the surroundings (temperature increases).

Endothermic Reaction – A reaction that absorbs energy from the surroundings (temperature decreases).

Activation Energy – The minimum amount of energy needed for a reaction to start.

Reaction Profile – A diagram showing the energy levels of the reactants and products in a reaction.