AQA GCSE Chemistry Paper 1 Review (Grade 9 Standard)

A comprehensive set of vocabulary flashcards covering the core concepts of AQA GCSE Chemistry Paper 1, including atomic structure, bonding, quantitative chemistry, chemical changes, and energy changes.

Atom

The smallest part of an element that can exist.

Atomic Radius

Approximately $0.1\,nm$ or $1 \times 10^{-10}\,m$.

Nucleus Radius

Less than $\frac{1}{10,000}$ of the radius of the atom, about $1 \times 10^{-14}\,m$.

Element

A substance made up of only one type of atom.

Compound

A substance which contains two or more different elements chemically combined in fixed proportions.

Symbol Equation Balancing

Ensuring there are the same number of each type of atom on both the reactant side and the product side of a chemical equation.

Proton

A positively charged particle ($+1$) found in the nucleus with a relative mass of $1$.

Neutron

A neutral particle ($0$) found in the nucleus with a relative mass of $1$.

Electron

A negatively charged particle ($-1$) found in shells orbiting the nucleus with a relative mass of approximately $\frac{1}{2,000}$.

Isotopes

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

Ion

A charged particle formed when an atom or molecule gains or loses electrons.

Electron Shell Capacity

The first shell holds up to $2$ electrons, while the second and third shells each hold up to $8$ electrons.

Mass Number

The sum of the number of protons and the number of neutrons in the nucleus of an atom.

Atomic Number

The number of protons in an atom, which determines the element’s identity.

Relative Atomic Mass ($A_r$)

The average mass of all the atoms of an element compared to $\frac{1}{12}$ of the mass of a carbon-12 atom.

Mixture

Consists of two or more elements or compounds which are not chemically combined.

Filtration

A physical process used to separate mixtures of insoluble solids and liquids.

Simple Distillation

Used to separate a solvent from a solution when the liquid needs to be collected.

Fractional Distillation

Used to separate two or more liquids based on their different boiling points using a fractionating column.

Crystallization

Used to separate a dissolved solute from a solution by evaporating the solvent and leaving the solid to dry.

Chromatography Pencil Line

The starting line drawn in pencil because pencil is insoluble and will not interfere with the movement of components.

Plum Pudding Model

JJ Thomson's theory that the atom is a cloud of positive charge with negative electrons embedded within it.

Alpha Scattering Experiment

Ernest Rutherford's experiment which proved the atom has a concentrated positive nucleus and is mostly empty space.

Mendeleev's Periodic Table

An arrangement of elements by atomic weight where gaps were left for undiscovered elements.

Noble Gases (Group 0)

Elements with full outer shells that are unreactive and monatomic.

Alkali Metals (Group 1)

Reactive metals with one electron in their outer shell; reactivity increases as you go down the group.

Halogens (Group 7)

Non-metal elements consisting of diatomic molecules; reactivity decreases as you go down the group.

Transition Metals

Elements in the middle of the periodic table that form colored compounds, have multiple ion charges, and act as catalysts.

States of Matter Symbols

Standard shorthand for physical states: $(s)$ solid, $(l)$ liquid, $(g)$ gas, and $(aq)$ aqueous solution.

Ionic Bonding

The strong electrostatic attraction between oppositely charged ions formed by the transfer of electrons from a metal to a non-metal.

Covalent Bonding

A chemical bond where pairs of electrons are shared between non-metal atoms.

Graphite

A giant covalent structure of carbon arranged in layers of hexagonal rings with delocalized electrons that conduct electricity.

Diamond

A giant covalent structure of carbon where each atom forms four strong covalent bonds, making it extremely hard.

Fullerenes

Molecules of carbon with hollow shapes, based on hexagonal rings, used for drug delivery and lubricants.

Metallic Bonding

Bonding caused by the sharing of delocalized electrons in a giant structure of metal atoms.

Alloy

A mixture of a metal with other elements to distort the layers, making the substance harder than pure metal.

Nanoparticles

Particles between $1\,nm$ and $100\,nm$ in size with a very large surface area to volume ratio.

Law of Conservation of Mass

States that no atoms are lost or made during a chemical reaction; mass of products equals mass of reactants.

Avogadro's Constant

The number of atoms, molecules, or ions in one mole of a substance, defined as $6.02 \times 10^{23}$.

Molar Calculation Formula

\text{Mass (g)} = \text{Relative Formula Mass (M_r)} \times \text{Moles}.

Limiting Reactant

The reactant that is completely consumed first in a reaction, determining the maximum mass of product formed.

Concentration ($mol\,dm^{-3}$)

Calculated as $\frac{\text{Moles}}{\text{Volume in } dm^3}$.

Percentage Yield

$\frac{\text{Mass of product actually made}}{\text{Maximum theoretical mass}} \times 100$.

Atom Economy

\frac{\text{M_r of desired product}}{\text{Sum of M_r of all products}} \times 100.

Molar Volume of Gas

One mole of any gas occupies $24\,dm^3$ at room temperature ($20^\circ\text{C}$) and pressure ($1\,atm$).

Oxidation (OIL RIG)

The loss of electrons during a chemical reaction.

Reduction (OIL RIG)

The gain of electrons during a chemical reaction.

Displacement Reaction

A reaction where a more reactive element takes the place of a less reactive element in a compound.

Strong Acid

An acid that is completely ionized or fully dissociated in aqueous solution, such as $HCl$ or $H_2SO_4$.

Weak Acid

An acid that is only partially ionized in aqueous solution, such as citric acid or ethanoic acid.

Electrolysis

The process of using electricity to split an ionic compound into its elements when it is molten or dissolved.

Anode

The positive electrode where negative ions lose electrons (oxidation).

Cathode

The negative electrode where positive ions gain electrons (reduction).

Exothermic Reaction

A reaction that transfers energy to the surroundings, resulting in a temperature increase.

Endothermic Reaction

A reaction that takes in energy from the surroundings, resulting in a temperature decrease.

Activation Energy

The minimum amount of energy that particles must possess to react upon collision.

Titer

The difference between the final and initial volume readings on a burette during a titration.

Hydrogen Fuel Cell

A device that generates electricity by reacting hydrogen and oxygen to produce water as the only waste product.