Term | Definition |
Alkali metals | Very reactive metals in group 1 of the periodic table, e.g. sodium. |
Alkalis | Substances which produce OH- ions in water. |
Aquifer | Underground layer of permeable rock or loose materials (gravel or silt) where groundwater is stored. |
Atom | The basic “building block” of an element which cannot be chemically broken down. |
Atomic number | The number of protons found in the nucleus of an atom. |
Attact | Move towards, for example, unlike charges attract. |
Balanced equation | Chemical equation where the number of atoms on each side of the equation balance each other. |
Barium chloride | Testing chemical for sulfates in water. |
Boiling point | Temperature at which the bulk of a liquid turns to vapour. |
Catalyst | A chemical that speeds up a reaction but is not changed or used up by the reaction. |
Charge(s) | A property of matter- charge exists in two forms, positive and negative, which attract each other. |
Chemical properties | The characteristic reactions of substances. |
Chlorination | Addition of chlorine to water supplies to kill micro-organisms. |
Close packed metal ions | Structure of a metal. |
Compound | Two or more elements which are chemically joined together, e.g. H2O. |
Covalent bonds | Bonds between atoms where some of the electrons are shared. |
Delocalised electrons | Electrons which are free to move away through a collection of ions- as in a metal. |
Dot and cross model | A drawn model representing the number of electrons in the outside shell of bonding atoms or ions. |
Double covalent bond | Covalent bond where each atom shares two electrons with the other atom. |
Electron gain | Gaining of electrons to form negative ions. |
Electron loss | Losing of electrons to form positive ions. |
Electron shells | The orbit around the nucleus likely to contain the electron. |
Electronic structure | The number of electrons in sequence that occupy electron shells, e.g. the 11 electrons of sodium are in sequence 2,8,1. |
Electrons | Small particles within an atom that orbit the nucleus (they have a negative charge). |
Electrostatic attraction | Attrraction between opposite charges, e.g. between Na+ and Cl-. |
Elements | Substances made out of only one type of atom. |
Filtration | The process of filtering river or ground water to purify it for drinking water. |
Flame test | Test where a chemical burns in a Bunsen flame with a characteristic colour- tests for metal ions. |
Giant ionic lattice | Sodium chloride forms a lattice, also called a giant ionc structure. |
Giant molecular structures | A large regular three-dimensional covalently bonded structure containing more than one non-metal element. |
Group | Within the periodic table the vertical columns are called groups. |
Group 1 metals | Metals in group 1 of the periodic table, e.g. lithium, sodium and potassium. |
Group 7 elements | Non-metals in group 7 of the periodic table, e.g. fluorine, bromine and iodine. |
Halogens | Reactive non-metals in group 7 of the periodic table, e.g. chlorine. |
Hardness | Hardness of solid material as tested by the scratch test. |
Helium | Second element in the periodic table; an alpha particle is a helium nucleus. |
Intermolecular force | Force between molecules. |
Ionic bond | A chemical bond between two ions of opposite charge. |
Ionic equation | An equation representing the formation of ions by the transfer of electrons. |
Ionises | Adds or removes electrons from an atom leaving it charged. |
Ions | Charged particles (can be positive or negative) |
Isotopes | Atoms with the same number of protons but different number of neutrons. |
Lustrous | Shiny |
Mass number | Number of protons and neutrons in a nucleus. |
Melting point | The temperature at which a solid turns into a liquid. |
Metal halide | A compound of a metal and a halogen, e.g. potassium bromide. |
Metallic bonding | The bonding between close-packed metal ions due to delocalised electrons. |
Metallic properties | The physical properties specific to a metal, such as lustre and electrical conductivity. |
Metals | Solid substances that are usually lustrous, conduct electricity an form ions by losing electrons. |
Minerals | Natural solid materials with a fixed chemical composition and structure, rocks are made of collections of minerals; mineral nutrients in our diet are things like calcium and iron, they are simple chemicals needed for health. |
Molecular formula | The formula of a chemical using chemical symbols in the periodic table, e.g. methane has a molecular formula of CH4. |
Molecule | Two or more atoms which have been chemically combined. |
Molten liquid | A liquid that has just melted, usually referring to rock, ores, metals or salts with very high melting points. |
Negative ion | An ion made by an atom gaining electrons. |
Neutrons | Small particle which does not have a charge found in the nucleus of an atom. |
Nickel catalyst | A catalyst used in the hardening of margarine. |
Nitrate residue | Unwanted residues sometimes found in water contaminated by farm run-off. |
Non-metals | Substances that are dull solids, liquids or gases that do not conduct electricity and form ions by gaining electrons. |
Nucleons | Protons and neutrons (both found in the nucleus). |
Nucleus | Central part of an atom that contains protons and neutrons. |
Oxidation | The process of electron loss. |
Period | A row in the periodic table. |
Periodic table | A table of all the chemical elements based on their atomic number. |
Pesticide residue | Unwanted residues sometimes found in water contaminated by local pesticide use. |
Physical property | Property that can be measured without changing the chemical composition of a substance, e.g. hardness. |
Positive ion | An ion made by an atom losing electrons. |
Precipitate | Solid formed in a solution during a chemical reaction. |
Precipitation reaction | Chemical test in which a solid precipitate is formed- tests for metal ions. |
Product | Molecules produced at the end of a chemical reaction. |
Protons | Small positive particles found in the nucleus of an atom. |
Reactants | Chemicals which are reacting together in a chemical reaction. |
Reduction | The process of electron gain. |
Relative atomic mass | The mass of an atom compared to 1/12th of a carbon atom. |
Relative formula mass | The sum of the relative atomic masses in a compound. |
Reservoir | A water resource where large volumes of water are held. |
Sea water | Water containing high levels of dissolved solids making it undrinkable. |
Sedimentation | A process during water purification where small solid particles are allowed to settle. |
Silver nitrate | A chemical used for testing for halide ions in water. |
Single covalent bond | Bond between to two atoms in which each atom shares one electron. |
Stable electronic structure | An achieved structure where the outer electron shell of an atom is full. |
Sub-atomic particles | Particles that make up an atom, e.g. protons, neutrons and electrons. |
Substrate | Molecules at the start of a chemical reaction. |
Thermal decomposition | The breaking down of a compound into two or more products on heating. |
Transition element | An element in the middle section of the periodic table, between the group 1 and block and the group 3 to 0 (zero) block. |
Water conservation | The act of reducing water consumption through planned choice, e.g. hosepipe bans and water metering. |
Water resources | Places from where water is extracted or where it is stored, e.g. aquifers, reservoirs or lakes. |