Atom
the building block of matter. It is the smallest particle of an element. An atom is made up of protons and neutrons in a central nucleus surrounded by electrons that orbit the nucleus in constant motion.
Boiling
the process whereby heat is applied to a liquid causing bubbles of gas to form and rise to the surface.
Boiling point
the temperature at which a liquid changes to a gas.
Characteristic
a feature which sets it apart.
Chemical change
a change which results in a new substance being formed. It is not usually reversible.
Chemical reaction
a reaction in which new substances are formed. Reactants react together to form products. That is chemical changes take place.
Chemistry
the study of matter and the way that matter changes.
Classification
putting things into groups.
Compound
A chemical substance made up of two or more different types of elements bonded together in a definite ratio. They cannot be separated by physical means.
Compression
able to be forced into less space.
Condensation
the process whereby a gas changes to a liquid.
Crystallisation
the process in which crystals form from a solution or from molten material.
Decantation
to pour off the liquid after the solid has been allowed to settle from a suspension.
Dissolve
solute particles become dispersed throughout a solution, so they are no longer visible.
Distillation
a technique used to separate a solvent from a solution. It involves evaporation of the solution and condensation of the solvent vapour.
Electron
Negatively charged particle of an atom. Orbits the positively charged nucleus.
Element
is a substance made of only one type of atom. It cannot be chemically split into simpler substances.
Equation
a 'sentence' of symbols and formulae that represent what has happened in a chemical change.
Evaporation
the process whereby a liquid changes to a gas without boiling.
Filtration
the process in which a mixture is brought into contact with some porous material called the filter which allows the liquid but not the solid to pass through its holes. The solid that remains is called the residue and the liquid part is called the filtrate
Forces of attraction
a 'pulling' between two bodies.
Freezing
the process whereby a liquid changes to a solid.
Formula
the combination of symbols representing a molecule. As well as the elements present, the formula gives the number of each type of atom present eg C6H12O6 means that a molecule of glucose contains 6 atoms of carbon, 12 atoms of hydrogen and 6 atoms of oxyg
Freezing point
the temperature at which a liquid undergoes a phase change to become a solid.
Gas
a substance that consists of particles that move about freely and take on the shape of the container. Gases do not have a fixed volume.
Immiscible
description of two liquids which do not mix eg kerosene and water.
Insoluble
not able to be dissolved.
Liquid
a substance that consists of particles that take on the shape of the container but have a fixed volume.
Kinetic theory
the theory that matter is made up of particles which are in constant random motion.
Mass
the quantity of matter in an object. (It is related to weight but not the same.)
Matter
anything that has mass and occupies space.
Melting
the process whereby a solid changes to a liquid.
Melting point
the temperature at which a substance changes from a solid to a liquid.
Miscible
the ability of 2 liquids to mix into one another.
Mixture
a substance which can be separated into 2 or more pure substances and in which the relative amounts of the pure substances can vary.
Molecule
2 or more atoms joined together by chemical bonds.
Nucleus
dense centre of an atom containing protons and neutrons.
Opaque
not able to transmit light.
Particle
a small unit of matter
Particle Model of matter
the theory that all matter is made up of particles.
Periodic table
a table of all the elements.
Phase change
a change of the physical state of a substance. (eg solid to liquid)
Physical change
a change which does not result in a new substance being formed. A physical change is usually able to be reversed
Products
substances that are produced as a result of a chemical reaction.
Property
an aspect of the appearance or behaviour of a material by which it can be recognised.
Proton
the positively charged particle in the nucleus of an atom.
Pure substance
a substance in which all the particles are the same.
Reactants
Substances that react together in a chemical reaction.
Solid
a substance in which the particles are held together in a rigid shape. They have a fixed volume and do not take on the shape of their container.
Solidification
the process whereby liquid changes to a solid.
Soluble
able to be dissolved.
Solute
the substance whose particles are spread through the other substance ie the substance dissolved in the solvent.
Solution
a mixture in which the particles of one substance are spread evenly throughout the other i.e. formed when a solute dissolves in a solvent.
Solvent
the substance which does the dissolving ie substance in which the solute dissolves to form a solution.
States of matter
refers to the physical phase of matter ie whether it is solid, liquid or gas.
Sublimation
the process whereby a solid changes directly to a gas without passing through the liquid state and vice versa.
Suspension
a mixture in which all the components are visible and the particles can be kept uniformly distributed throughout the mixture only by stirring.
Symbol
shorthand way of writing an element.
Transparent
having the property of transmitting light through its substance.
Vaporisation
the process whereby a liquid changes to a gas by boiling or evaporation.
Volume
the space occupied by an object.