C4 Keywords

Atom - Smallest part of an element that can take part in chemical reactions.

Element - Substance that consists only of atoms with the same atomic number.

Subatomic - Particles from which atoms are made, including protons, neutrons, and electrons.

Particle - A minute portion of matter.

Electron - Subatomic particle found outside the nucleus of an atom. It has a charge of -1 and a very small mass compared to protons and neutrons.

Nucleus - Relatively heavy central part of an atom, made up of protons and neutrons.

Proton - Subatomic particle found in the nucleus of an atom. It has a charge of +1 and a relative mass of 1. 

Neutron - Subatomic particle found in the nucleus of an atom. It has no charge and a relative mass of 1. 

Atomic number - Number of protons in the nucleus of an atom. 

Periodic table - Table in which the elements are arranged in rows (periods) and columns (groups) in order of their atomic number. 

Mass number - Total number of protons and neutrons in the nucleus of an atom. 

Isotope - Atoms of the same element that have different numbers of neutrons in their nuclei are called isotopes. 

Chemical symbol - Letter or pair of letters used to represent on atom of an element, eg H represents one atom of hydrogen; Fe represents one atom of iron. 

Compound - Substance made up of two or more different elements, chemically combined. 

Shell - Region of space in an atom that can hold a number of electrons. 

Electronic structure - Arrangement of the electrons in an atom in shells around the nucleus. 

Ion - Atom, or group of atoms, that has gained or lost one or more electrons and so is electrically charged. 

Ionic bond - Strong electrostatic force of attraction between oppositely charged ions. Ionic bons act in all directions. 

Dot and cross diagram - Diagram that shows how the electrons are arranged in a molecule or in ions. 

Ionic compound - Compound made up of ions. 

Giant ionic lattice - Regular, three-dimensional pattern of ions held together by strong electrostatic forces of attraction.

Period - Horizontal row in the periodic table. The atomic number of each element increases by one, reading them left to right.

Group - Vertical column in the periodic table. Elements in a group have similar chemical properties. 

Covalent compound - Compound in which the atoms are joined together in molecules by covalent bonds. 

Covalent bond - Shared pair of electrons between atoms in a molecule.

Molecule - Particle made up of two or more atoms chemically bonded together. 

Molecular formula - Description of a compound of an element that uses symbols for atoms. It shows the relative number of atoms of each type in the substance. 

Displayed formula - Description of a covalently bonded compound or element that uses symbols for atoms and that also shows the covalent bonds between the atoms. 

Simple molecule - Molecule containing only a few atoms joined by covalent bonds. 

Intermolecular force - Relatively weak force between a molecule and its neighbours. 

Group 1 - Group (vertical column) of elements on the left hand side of the perioidic table. An atom of each element hasone electron in its outer shell. 

Alkaline - Having a pH greater than 7. 

Alkali metal - Element in Group 1 of the periodic table (lithium, sodium, potassium, rubidium, caesium, francium). 

Flame test - Means of identifying metals by observing the colour they produce in the flame of a Bunsen burner. 

Group 7 - Group (vertical column) of elements on the right hand side of the periodic table. An atom of each element has seven electrons in its outer shell. 

Halogen - Element in Group 7 of the periodic table (fluorine, chlorine, bromine, iodine, astatine). 

Metal halide - Compound made up of metal and halogen. 

Displace - To replace (push out) an element in a compound.  

Displacement reaction - Reaction in which one element replaces another in a compound. 

Reduction - Chemical reaction in which oxygen is removed from a compound, or an atom or ion gains electrons. 

Transition element - Element that occurs between Groups 2 and 3 in the periodic table. 

Catalyst - Substance that speeds up a reaction without being used up in the reaction. 

Thermal decomposition reaction - Reaction in which a reactant is broken up into simpler products by the action of heat. 

Precipitation reaction - Reaction in which a precipitate forms. 

Precipitate - Suspension of small, solid particles, spread throughout a liquid or solution. 

Tensile strength - Resistance of a material to beraking when stretched. 

Metallic bond - Force of attraction between positively charged metal ions and delocalised electrons in a metal. 

Crystal - Piece of material in which the atoms, molecules, or ions are arranged in a regular three-dimensional pattern. 

Resistance - Measure of how difficult it is for an electric current to flow through a material. 

Superconductor - Metal that has a very low (almost zero) electrical resistance. 

Aquifer - Layer of rock that stores a large quantity of water. 

Pollutant - Substance released into the environment which can cause harm to living things, including humans.

Chlorination - Addition of chlorine to water to kill microbes.

Sedimentation - Process by which larger particles of solid in a liquid sink to the bottom over time. 

Filtration - Process by which smaller particles of solid are removed from a liquid by passing the liquid through a filter. 

Distillation - Process by which a liquid is purified by heating it to form a gas and then condensing a gas back to a liquid in a clean container.