Chemistry Paper 1 Key Concepts

Comprehensive vocabulary flashcards covering key concepts in Chemistry, including atomic structure, bonding, quantitative chemistry, states of matter, and chemical changes.

Structure of the atom

Consists of protons and neutrons in a tiny central nucleus with electrons orbiting in fixed shells (energy levels).

Proton

A sub-atomic particle with a mass of $1$ and a charge of $+1$.

Neutron

A sub-atomic particle with a mass of $1$ and a charge of $0$.

Electron

A sub-atomic particle with a mass of $\frac{1}{2000}$ and a charge of $-1$.

Isotopes

Atoms of the same element that have the same number of protons but different number of neutrons.

Relative atomic mass (RAM)

The mean relative mass of the isotopes in an element; it is not always a whole number.

Mendeleev's Periodic Table

Arrangement of elements in order of increasing atomic mass, leaving gaps to predict properties of unknown elements.

Modern periodic table

Arrangement of elements in order of increasing atomic number, with vertical columns called groups.

Electronic configuration

States the number of electrons in each shell; for example, sodium ($Na$) with $11$ electrons is $2.8.1$.

Cation

A positive ion, usually a metal, formed when atoms lose electrons (e.g., $Li^+$, $Mg^{2+}$).

Anion

A negative ion, usually a non-metal, formed when atoms gain electrons (e.g., $Cl^-$, $O^{2-}$).

Ionic bond

The strong electrostatic force of attraction between oppositely charged ions.

Covalent bond

A shared pair of electrons between two atoms, resulting in the formation of molecules.

Metallic bond

The attraction between fixed positive ions and a 'sea' of delocalised electrons.

Malleable

The property of metals that allows them to be hammered into shape as layers of ions slide over each other.

Giant covalent structures

Unusual covalent structures that hold many atoms together in a giant molecule, such as diamond and graphite.

Diamond

A form of carbon where each atom is bonded to $4$ others in a giant lattice; it is very hard and does not conduct electricity.

Graphite

A form of carbon where each atom is bonded to $3$ others in layers; it conducts electricity and acts as a lubricant.

Relative formula mass (RFM)

The relative mass of a compound found by adding the masses of its constituent atoms.

Mole

A unit representing $6.02 \times 10^{23}$ particles of a substance (Avogadro’s number).

Empirical formula

The simplest whole number ratio of atoms in a substance.

Conservation of mass

The principle that in all reactions, mass is not created or destroyed.

Concentration

The mass of solute dissolved in $1\,dm^3$ of a solvent, calculated as \text{mass (g)} \div \text{volume (dm^3)}.

Limiting reactant

The reactant that is not in excess and determines the mass of product formed.

Pure substance

A substance with a fixed composition and a sharp melting point, not mixed with anything else.

Filtration

A separation method where filter paper catches insoluble or larger pieces, allowing liquid through.

Crystallisation

A method to separate a solute from a solution by evaporating the solvent to leave crystals.

Distillation

A process that separates a liquid from a mixture by heating to evaporate it and then condensing it.

Fractional distillation

A method used to separate a mixture of liquids based on their different boiling points.

Chromatography

A technique to separate mixtures of soluble substances using a mobile phase (solvent) and a stationary phase (paper).

Potable water

Water that is safe to drink, treated via sedimentation, filtration, and chlorination.

Acids

Substances that in solution have a pH lower than $7$ and are a source of hydrogen ions ($H^+$).

Alkalis

Soluble bases that in solution have a pH above $7$ and are a source of hydroxide ions ($OH^-$).

Strong acid

An acid that dissociates completely into ions when dissolved in water (e.g., hydrochloric acid).

Neutralisation

A reaction where an acid reacts with a base to form a salt and water ($H^+ + OH^- \rightarrow H_2O$).

Titration

A technique used to prepare a soluble salt by adding a specific volume of alkali to an acid until the end point is reached.

Precipitation reaction

A reaction where soluble salts react together to form an insoluble salt called a precipitate.

Electrolyte

An ionic substance with freely moving ions that can conduct electricity when liquid or dissolved in water.

Electrolysis

The process where electrical energy from a d.c. supply decomposes electrolytes.

Oxidation

The gain of oxygen or the loss of electrons ($OIL$).

Reduction

The loss of oxygen or the gain of electrons ($RIG$).

Displacement reaction

A reaction where a more reactive metal displaces a less reactive metal from its compound.

Bioleaching

A biological method of extracting metals using bacteria.

Phytoextraction

A biological method of extracting metals using plants to absorb metal compounds.

Life cycle assessment

An evaluation of the environmental impact of a product from raw materials to disposal.

Dynamic equilibrium

A state in a reversible reaction where the forward and backward reactions happen at the same rate.

Haber process

The industrial process for making ammonia using a nitrogen and hydrogen reversible reaction ($N_2 + 3H_2 \rightleftharpoons 2NH_3$).