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Science Dictionary, Glossary and Terms

science dictionaryCorrosive - Is the wearing away of the surface of a metal by chemical reactions with oxygen and water. When a metal reacts with substances around it, such as water or air, it corrodes. 

Many transition metals corrode slowly, if at all, but iron and steel corrode quickly. 

The corrosion of iron and steel mixed with water and air (oxygen) is called rusting.  Rusting damages metal parts so it is important to prevent it.



Absorbent - a substance that can soak up a liquid, or to take in energy and retain it.

Absorber - an absorber does not reflect or transmit particles or radiation that hit it. Aluminium foil is an absorber of alpha particles.  A dark, dull surface is an absorber of infra-red radiation.

Accuracy - is a term that refers to the properties of a measuring instrument. 

Acid - an acid is a chemical that will neutralize a base such as an alkali.  There are many different kinds of acid.   Lemons are sour because they contain citric acid. Acid in vinegar is called acetic acid.  It is a substance that disolves in water to form a solution with a pH below 7.  An acid contains hydrogen which can be replaced by a metal to form a salt.  When an acid dissolves in water H+(aq) ions are formed.  A strong acid completely ionises in water and a weak acid only partly ionises.  Common strong acids include hydochloric acid, HCl, sulphuric acid, H2SO4 and nitric acid, HNO3.  A common weak acid is ethanoic acid, CH3COOH.

Acid rain -  is a kind of pollution.  Sulphur and nitrogen oxides are produced from the burning of fossil fuels.  When they escape into the atmosphe, they form sulphuric and nitric acids.  Thes acids can have effects on our environment, e.g. erode stonework, lower the pH of lakes and rivers killing our wildlife, and cause damage to trees. 

Adhesive - made to stick like glue.

Air - is a mixture of gases.

Alkali - is a metal oxide or hydroxide (base) that dissolves in water to form a solution with a pH greater than 7.  An alkali is neutralised by an acid to form a salt and water.  Common alkalis include sodium hydroxide, NaOH, potassium hydroxide, KOH, calcium hydroxide, Ca(OH)2 and ammonium hydroxide, NH4OH.

Alloy - is a metal made by melting and mixing two or more metals together, e.g. brass is a mixture of copper and zinc and bronze is an alloy of copper and tin.

Amphibians - are animals that live in water and on land.  They have smooth, moist skins and lay their eggs in water.

Antennae - a pair of sensory organs found on the heads of insects.

Apparatus - are the things (equipment) needed to carry out an experiment.

Aquatic - belonging to , or living in water.

Atomic - an atom is the smallest particle (unit of matter) of an element which can exist and be part of a chemical reaction (a source of nuclear energy).  The tiniest part of a substance. Atomic is the use of atomic bombs or energy.


Bacteria - are very small single-celled  organisms with no nucleus.

Balance/Top Pan Balance - is an instrument which is used to measure mass.

Barbule - branches that form from the hollow shaft (Rachis) of a feather.  When birds preen (groom) their feathers they spread oils over them which 're-hooks' the barbules.

Battery - a battery consists of a number of electrical cells.  These cells are usually connected in series to give a highter voltage than that from a sinlge cell.

Bedrock - solid rock immediatley beneath the surface soil.

Biodegradable - is a material that can rot and decay away quickly after we have used it.

Biologist - to study biology you will need to know the 7 life processes.  A memory trick to remember what the life processes are is 'MRS GREN'.

     M - Movement - the moving parts of an organism

     R - Reproduction - Producing offspring

     S - Sensitivity - Reacting and responding to the environment

     G - Growth - Increasing is size to adulthood

     R - Respiration - Turning food into energy

     E - Excretion - Getting rid of waste

     N - Nutrition - Getting food to stay alive

Birds - are animals that have feather and wings.  They lay eggs with hard shells and usually fly.

Bonded - Something that is bound, fastened or joined together.

Braided - interwoven hair and thread, or other fibres and yarns.

Bulb - part of the root of a plant which resembles a ball (e.g. onion).

Bunsen burner - is a gas burner used in a lab during experiments.


Canopy - a hanging cover forming a shelter.

Carnivores - are animals that eat other animals.

Catalyst - is something that alters the speed (speeds up) of a chemical reaction or change without being used up at the end of it or permanently changed itself.

Cells - one of the smallest parts of a plant or animal tissue.

Circuit - is one or more conducting paths between the two electrodes of a cell or battery of cells.

Characteristics - the distinguishing features or quality of something.

Chemicals - are the substances used in chemistry doing experiments..

Chemist - a chemist needs to be able to identify acids and alkalis.  Universal Indicator can be used to show the pH of a substance. 

Classifying - is to sort things into different groups.

Climate - the weather conditions of an area (e.g. the hot Siberian desert, the coldness of Iceland).

Compound - is a substance that has two or more elements in it.

Concave - describes the shape of a lens or other object where the center is thinner than the outside.

Conclusion - things that can be worked out from doing an experiment (making a decision). To draw to a close, to finish or conclude with an explanation, judgement or opinion based on interpretations.

Condensation - is the change from a gas to a liquid or solid.

Conifers - are relating to or part of trees or shrubs that do not have flowers and their seeds are made in cones.

Consistence - a degree of thickness or smoothness of a substance.

Controlled Variable - the things that you try to keep the same in an experiment or investigation.

Corrosion - is the wearing away of the surface of a metal by chemical reactions with oxygen and water.  Rusting is one example of corrosion.

Crystals - a solid with a symmetrical arrangement of faces, usually bright and clear.

Current - is a flow of electric charge.  The current is a metallic conductor is due to a flow of negatively charged electrons. 


Data - a collection of observations, measurements and/or facts.

Decompose - the breaking down of parts from a whole - to decay or rot, wasting away.

Dense - made up of very closely packed particles.

Dilute -  is to make a liquid weaker or thinner by adding more liquid, usually more water.

Dispersion - is the splitting of white light into the seven colors of the visible spectrum - rainbow.

Dissolving - is the process that occurs when a solute is added to a solvent and the solute disappears.  The particles of the solute fit between the particles of the solvent.  The solute can be recovered by the evaporation process.  To mix a solid with a liquid so it becomes a liquid as well. To melt, to become a liquid (ice melting, sugar disolving in hot tea).

Distillation - this is to separate a liquid from other liquids by boiling it and condensing the steam. A substance that has been through an evaporation and condensing process.


Earth - is the planet that we inhabit.  In electricity, the term refers to an electrical connection to the Earth.

Ecosystem - is the sum total of all the living organisms and non-living factors in an environment and the way they interact. The relationship between the environment, its animals and its plants.

Eiderdown - Eider is a duck which has very soft feathers, eiderdown is the down (feathers) from this duck.

Element - is a pure substance made of one kind of atom.  It cannot be split up into anything simpler without losing its characteristics.  A substance that cannot be separated into simpler substances.

Energy - is transfered by heating by; radiation, conduction and convection.  The amount of energy transfered is measured in joules.

Environment - the conditions or surroundings in which people and animals live.

Enzymes - is a substance that speeds up a chemical reaction in the body (a biological catalyst).  Each enzyme works best at a particular temperature and pH.

Erode - is to wear away.

Erosion - is the process where rocks are worn away.

Evaluating - to decide if you have done something the best way and seeing what you could improve.

Evaporation - is the process in which a liquid changes to a vapour, due to particles leaving the surface of the liquid.  A liquid turns to a gas.  Changing from a liquid or a solid into vapours (gas).

Evidence - is anything that gives a reason to believe something.

Expand - is when the size of a substance increases due to being heated.  The particles gain energy and move further apart.

Experiment - a test to find something out.  

Explosion - is a very rapid reaction accompanied by a large expansion in gases.


Fabric - any material made of fibers or yarn which has been woven or knitted together.

Fair Test - is controlling some of the things used or done in a test so they do not change.  An experiment in which only one variable is changed at a time to allow a fair comparison.

Felt - is tightly matted fabric made of wool which has had the fibers worked together under pressure.

Ferns - a plant with strong stems, roots and leaves and do not have seeds.

Fertilize - to provide a plant with pollen to bring about fertilization.

Filaments - are single stands of fiber.

Filter - is to separate solids (that do not dissolve) from liquids.

Fish - are cold-blooded animals that live in water, they have a backbone, scaly skin, tails and fins for swimming and gills for breathing.

Flammable - a substance or material that easily sets on fire.

Flowering Plants - any plant that produces flowers and fruit.

Force - is a push or pull.  Force is measured in units called newtons (N).

Formula - is a way of writing scientific information using letters, numbers and signs.

Friction - occurs when two surfaces move over each other.    Air resistance and water resistnace are friction forces caused by the movement of something through the air or the water.

Freeze - is when you cool something to a very low temperature and it usually forms ice.

Function - is the special purpose or use of something.


Galaxy - is a group of millions of stars held together by gravity, like the Milky Way.

Gas - is a state of matter in which the particles move rapidly and are very spread out.

Gravity - is the force of attraction between any two bodies.  It increases with increasing mass of the bodies and decreases if they are further apart.


Habitat - is a place where an organism lives. It is the natural home of a plant or animal.

Herbivores - are animals that eat only plants.

Humidity - is warm dampness, it is a measure of the amount of water in the air.

Humus  - bits of decaying plants and animals found in soil.


Igneous - (of rock) is the matter formed as moulten (entremely hot liquid) rock cools and hardens.

Indicator - is a chemical that can show if a substance is acidic or alkaline by changing color.  Color turns red in acid and blue in alkali.

Infiltration - is the passing of a liquid or gas through a substance by means of a filter.

Insoluble - this is when a solid is unable to dissolve into a liquid.

Insulator - halts the passage of electricity, heat or sound through an object or substance.

Invertebrates - are animals without a backbone, such as worms.

Investigating - is to look for clues and try to work out what they mean.


Joule (J) - is the unit for measuring energy or work.


Kaleidoscope - is a tube filled with colored paper, which is lined with mirrors placed at different angles.  Turning the tube will create amazing patterns for you to see through a small hole at the end of the tube.

Keratin - is a fibrous protein found in hair and nails.

Kinetic Energy - is the kind of energy in moving things.


Larva, larvae - is an insect that is still in its caterpillar state.

Leaf - is a flat green blade attached to the stem of a plant.

Lichen - is a mutualistic relationship between a fungus and an alga (simple plant).  They can be seen as crusty patches on tree trunks and walls.

Liquid - is a state of matter in which the particles are close together but randomly arranged.  The particles can move over each other.


Magnetic - applies to any object or material that is repelled or attracted by a magnet.  Magnetic materials include iron, steel, cobalt and nickel.

Magnetic field - is an area where a magnetic material experiences a force.  Magnetic fields exist around permanent magnets, electromagnets and electric currents.

Magnification - to be magnified.  To increase the size of an object to make it bigger than it actually is.

Mammals - are animals that are warm-blooded, usually have fur or hair and feed their young with milk from their mother.

Matter - is the material that something is made up of.

Melting - is when a solid changes to a liquid at the melting point by heating.

Melting Point - is when the temperature at which a solid changes to a liquid.

Measuring Cylinder - is an instrument that measures the volume of a liquid.

Metamorphic - (of rock) is a complete change from its original state caused by heat and pressure.

Method - is an orderly way of doing something.

Methodology - is a scientific study of method.  A system of methods used in a particular activity.

Microbes - are very small living things, usually only one cell big.  A tiny organism that can only be seen with a microscope.  Some microbes can cause disease.

Milky Way - is the spiral galaxy of stars which the Earth is part of.

Minibeasts - are miniature or very small animals such as insects.

Mixture - is two or more substances mixed together without actually joining them so that they can be separated again.

Molecule - is a group of atoms joined together.

Moss -  a plant that has weak roots, thin, delicate leaves and do not have seeds.

Moult - is the shedding or casting off of feathers, hair, fur and skin.


Nectar - is the sweet juice of flowers from which bees make their honey.

Neutralisation - Acids react with bases, alkalis, reactive metals and carbonates.  This is called a neutralisation reaction.

     Acid + Alkali   ->  Salt + Water
     Acid + Base     ->   Salt + Water
     Acid + Metal   ->   Salt + Hydrogen
     Acid + Carbonate   ->   Salt + Water + Carbon Dioxide

Neutron - is an atomic particle found in the nucleus.  It is similar in mass to a proton but has no charge.

Newton (N) - is the unit of force.

Nocturnal - active during the night.


Observations - the things that can be seem, watched during an experiment and the taking of notes to record facts based on the experiment.  Try using all your senses to notice what is happening.

Omnivores - are animals that eat both animals and plants.

Opaque - does not allow light through.

Orbit - the curved path taken by an object that moves round another object like a planet around the Sun.

Organism - (of animal, plant) a section or piece resembling a living creature in behaviour or structure.


Particles - are the extremely tiny parts  (substances) that scientists believe everything is made up of.

Permeable - is a material which allows water or liquids to flow through.

Photosynthesis - is the process from which plants use or changes sunlight into energy from the sun to make their own food.  This energy is their food which contains oxygen and glucose.  [carbon dioxide + water = glucose + oxygen] (also see photosynthesis definitions page)

Physical Change - is when you mix two substances and their particles become jumbled up together.  They do not necessarily combine chemically unless the atoms in the molecules are rearranged - this change is a physical change only.  This new substance is called a mixture and can usually be separated quite easily.

Physicist - a physicist needs to get units right in calculations. 

    Physical Quantity      S.I. Units           Symbol

         Length                       Metres                  m
         Mass                         Kilograms            kg
         Time                          Seconds              s
         Force                         Newtons              N
         Energy                      Joules                   J                  

Pipette - a thin glass or plastic tube used to measure liquids.

Planet - is a large body that orbits a star.

Plates - are huge sections of the Earth's crust which float on the mantle.

Pole - in magnetism, the strongest part of a magnet. The pole of a magnet that points towards magnetic North is called its North seeking pole.

Pollination - is to fertilise by the transfer of plant pollen.  The wind, birds and bees can pass pollens around.

Predator - is an animal which hunts and kills other animals for their food.

Predicting - to say what you think is going to happen in an experiment or investigation.

Process - is a number of actions for making or doing something.

Properties - are what a material or substance is like and how it behaves.  Describes how a substance behaves.  It can describe any piece of the material (for example if a material is strong or soft).

Protein - are nitrogenous compounds that are essential for life.

Proton - is an atomic particle found in the nucleus.  It is similar in mass to the neutron but has a positive charge.



Rachis - (of feather) is the hollow shaft and network of hooks and barbules belonging to a feather.

Ray - is a narrow beam of light.

Reaction - is something that happens in response to something else.

Reaction Time - is the time that elapses between an event occurring and aperson responding to the event.

Recycled - is when something is used again in a system.

Reflect - is to bounce something back from a surface.

Reflection - is the change in direction when light or other wave motion rebounds at a boundary between two materials. 

Refraction - is the change in speed when light or other wave motions passes from one material into another. The change in speed causes a change in wavelength and may cause a change in direction.

Reliable - things that can be taken to be true.

Reptiles -  are animals that live mainly on land and lay eggs with soft shell.  They have dry, scaly skin and crawls along on their belly and have short legs.

Research - is an investigation or study to find out facts in order to reac a conclusion.

Residue - is something that remains behind or is left over.

Result - is what happens at the end of an experiment.

Rodent - is an animal with strong incisor (cutting teeth at the front).

Rusting - is an oxidation process of iron and steel.   Iron and steel rust in the presence of oxygen (air) and water.   Rust is hydrated iron(III) oxide.  Rust damages metal parts so it is important to try to prevent it.  One way is to alloy the iron and steel with other metals which resist rust.  Stainless steel is an alloy of iron wiht other metals such as chromium and nickel.  Tpresence of these other metals protects the stainless steel from corrosion and allows these metals to be used as kitchen sinks and cutlery.


Safety Specs - must be worn to protect your eyes from any danger.

Scale - is the marks on any measuring instrument.

Sedimentary - the material that has been deposited by wind or water.  The matter that forms at the bottom of a liquid.

Sieve - is when you separate a solid or a liquid by using a sieve.

Slaked lime - calcium hydroxide.

Soil - is the top layer of land on the Earth's surface.

Solar System - is a star and all the objects that orbit it.

Soluble - is the liquid that is produced after you have dissolved a solid into another liquid.

Solution - chemical: is the mixture of two or more substances, a solute dissolves in a solvent.   The substance made when a solid disappears in a liquid.  The process of solving a problem.

Specimen - is a sample of blood, urine or tissue which is used for analysis.

Spectrum - the range of colors that make up white light is called the spectrum. White light is a mixture of colors. When splitting light throught a prism you can see the spectrum of colors.

Stalactite - is a hanging formation of calcium carbonate dripping down from the roof of a cave.

Stalagmite - is the opposite of a stalactite; as it rises like a spike from the floor of a cave.

Star - is an astronomical object that generates energy due to nuclear fusion.  A star gives out light and/or other forms of electromagnetic radiation.

Static Electricity - is an unbalanced charge that is not moving.  A common cause of static electricity is the transfer of electrons when two objects are rubbed together.  The object that gains electrons becomes charged negatively while the object that loses electrons becomes charged positively.

Stem - is the long, thin, supportive central part of a plant which bears a flower, fruit or leaf.

Sun - is the Earth's star.

Symmetrical - is two halves that are mirror images of each other like butterfly wings.

Synthetic - is a substance or material which is not made up of natural substances like cotton or wool, but are man-made artifically from chemical reactions.


Tectonic plates - huge sections of the Earth's crust and upper mantle.

Temperature - is a measure of how hot or cold an object is.

Texture - is the appearance, feel and structure of a substance.

Thermometer - is an instrument used to measure temperature.

Tsunami - a large wave caused by an underwater eathquake or volcanic eruption.


Universe - is everything that exists.


Variables - are the things that can change during an experiment.  Something that can vary during an experiment.

Vertebrates - are animals with a backbone.

Volume - is how much room something takes up. It is measured in centimeters (cm3).


Wasted energy - energy that is not usefully transferred or transformed.

Waterproof - does not allow water to pass through.

Wavelength - the distance from one wave peak to the next wave peak along the waves.

Weight - is a force due to gravity acting on an object.


X-rays - are used to detect broken bones.  very penetrating, short wavelength electromagnetic waves.



Zero error - a systematic error, often due to the measuring instrument having an incorrect zero (forgetting that the end of the ruler is not at zero).

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