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.
Atomic Structure Part 2
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.
Electrons And The Periodic Table
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.
Covalent Boding Part 2
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.
The Group 1 elements
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.
The Group 7 Elements
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.
The Transition Elements
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.