Chemistry - Paper 2 Flashcards

A set of practice flashcards covering the key knowledge for Chemistry Paper 2, including atomic structure, the periodic table, bonding, calculations, and atmospheric science.

Structure of the atom

A nucleus containing protons and neutrons surrounded by electrons in shells.

Proton

A subatomic particle with a mass of $1$ and a charge of $+1$.

Neutron

A subatomic particle with a mass of $1$ and a charge of $0$.

Electron

A subatomic particle with a mass of $1/1850$ and a charge of $-1$.

Mass number

The number of protons + the number of neutrons in an atom.

Isotope

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

Relative atomic mass ($Ar$)

The mean mass of an atom relative to carbon-12; the mean mass of the isotopes of the element.

JJ Thomson

Identified electrons in 1897 through experiments leading to the discovery of subatomic particles.

Ernest Rutherford

In 1909, fired positive particles at gold foil to discover that atoms are mostly empty space with a positive nucleus.

Mendeleev

Arranged the periodic table in order of increasing relative atomic mass and left gaps to predict the properties of undiscovered elements.

Atomic number

The number of protons in the nucleus of an atom.

Electronic configuration

How the electrons are placed in shells, which can be written (e.g., 2.1) or drawn as circles with dots or crosses.

Ion

An atom or group of atoms with an electric charge.

Anion

A negatively charged ion formed by gaining an electron.

Cation

A positively charged ion formed by losing an electron.

Ionic lattice

A regular arrangement of ions held together by strong electrostatic forces between oppositely charged ions.

Covalent bond

A shared pair of electrons between two atoms.

Molecule

A group of atoms held together by covalent bonds, typically on the order of $10^{-10}\text{ metres}$.

Metallic bond

The force of attraction between metal ions and delocalised electrons.

Giant covalent structure

A giant lattice of atoms held together by covalent bonds, such as diamond or graphite.

Allotrope

Different structural forms of the same element.

Fullerenes

Simple molecules of carbon where each carbon has three covalent bonds to form spheres or tubes.

Relative formula mass ($Mr$)

The sum of the relative atomic masses of all the atoms in the formula of a compound.

Empirical formula

The simplest whole number ratio of atoms of each element present in a compound.

Law of conservation of mass

States that the total mass of reactants in a closed system remains constant because mass is neither created nor destroyed during a chemical reaction.

Concentration

The mass of a solute (in grams) divided by the volume of the solution (in $dm^3$), measured in $g/dm^3$.

Mole

A unit representing the Avogadro constant ($6.02 \times 10^{23}$) of particles.

Alkali metals (Group 1)

Soft metals with relatively low melting points that react with water to produce metal hydroxides and hydrogen gas; reactivity increases down the group.

Halogens (Group 7)

Non-metals whose reactivity decreases and melting/boiling points increase down the group.

Noble gases (Group 0)

Unreactive gases with a full outer shell of electrons.

Displacement reaction

A redox reaction where a more reactive element displaces a less reactive element from a solution of its salt.

Rate of reaction

The speed at which reactants are turned into products.

Activation energy

The minimum energy required for a chemical reaction to occur.

Catalyst

A substance that increases the rate of reaction by providing an alternative pathway with a lower activation energy, without being consumed.

Exothermic reaction

A reaction that transfers energy to the surroundings, associated with bond making.

Endothermic reaction

A reaction that takes in energy from the surroundings, associated with bond breaking.

Hydrocarbons

Compounds that contain only carbon and hydrogen atoms.

Crude oil

A finite resource consisting of a mixture of hydrocarbons arranged in chains or rings.

Fractional distillation

A process used to separate crude oil into simpler mixtures (fractions) like petrol, kerosene, and diesel oil.

Homologous series

A series of compounds with the same general formula, similar chemical properties, and a gradual variation in physical properties.

Cracking

The process of breaking down larger, saturated hydrocarbon molecules (alkanes) into smaller, more useful molecules (alkenes).

Greenhouse effect

The process where gases like $CO_2$, methane, and water vapour absorb and release heat radiated from the Earth, keeping the planet warm.