Science Practical Test

Keywords and Words

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Accurate

A measurement close to the true value

Acid

When dissolved in water its solution will have a pH value less than 7. Donates protons (H+ ions).

Activation Energy

The minimum energy needed for a reaction to take place.

Alkali metals

Elements in group 1 of the periodic table.

Alkane

A saturated hydrocarbon with general formula:

Alkene

Unsaturated hydrocarbon with the general formula:

Alloy

A mixture of two or more elements, at least one of which is a metal.

Anhydrous

A substance which does not contain water.

Anode

The positive electrode in electrolysis (PANIC)

Anomalies

Results that do not match the pattern seen in the other data collected or are well outside the range of other repeat readings (outliers),

Aqueous solution

The mixture made by adding a soluble substance to water.

Atmosphere

The relatively thin layer of gases that surround planet Earth.

Atom

The smallest part of an element that can still be recognised as that element.

Avogadro constant

The number of atoms, molecules or ions in one mole of any substance.

Balanced symbol equation

A symbol equation in which there are equal numbers of each type of atom on either side of the equation.

Base

The oxide, hydroxide or carbonate of a metal that will react with an acid, forming a salt as one of the products. If a base dissolves in water it is called an alkali. Bases are proton (H+) acceptors.

Biofuel

Fuel made from animal or plant products.

Blast furnace

The huge reaction vessels used in industry to extract iron from iron ore.

Bond energy

The energy required to break a specific chemical bond.

Carbon footprint

The total amount of green house gases emitted over the full life cycle of a product, service or event.

Categoric Variable

Categoric variables have values that are labels. For example "types of material".

Catalyst

A substance that speeds up a chemical reaction by providing a different pathway for the reaction that has a lower activation energy. The catalyst is chemically unchanged at the end of the reaction.

Cathode

The negative electrode in electrolysis

Chromatography

The process whereby small amounts of dissolved substances are separated by running a solvent along a material such as absorbent paper.

Climate Change

The change in global weather patterns that could be caused by excess levels of greenhouse gases in the atmosphere.

Closed system

A system in which no matter enters or leaves.

Collision Theory

An explanation of chemical reactions in terms of reacting particles colliding with sufficient energy for a reaction to take place.

Composites

Materials made of two or more different materials, containing a matrix or binder surrounding and binding together fibres or fragments of another material which acts as the reinforcement.

Compound

A substance made when two or more elements are chemically bonded together.

Continuous variable

Can have values (called a quantity) that can be given by measurement (for example, mass, volume, temperature etc).

Control group

If an experiment is to determine the effect of changing a single variable, a control is often set up in which the independent variable is not changed, thus enabling a comparison to be made. If the investigation is of the survey type a control group is usually established to serve the same purpose.

Control variable

A variable which may, in addition to the independent variable, affect the outcome of the experiment and therefore has to be kept constant or at least monitored.

Covalent bond

The bond between two atoms that share one or more pairs of electrons.

Covalent bonding

The attraction between two atoms that share one or more pairs of electrons.

Cracking

The reaction used in the oil industry to break down large hydrocarbons into smaller, more useful ones.

Data

Information, either qualitative or quantitative , that has been collected.

Delocalised electron

Bonding electron that is no longer associated with any one particular atom.

Dependent variable

The variable for which the value is measured for each and every change of the independent variable.

Diffusion

The automatic mixing of liquids and gases as a result of the random motion of their particles

Directly proportional

A relationship that, when drawn on a line graph, shows a positive linear relationship that crosses through the origin.

Discrete data

Data that can only take certain values.

Displacement reaction

A reaction in which a more reactive element takes the place of a less reactive element in one of its compounds or in solution.

Distillation

Separation of a liquid from a mixture by evaporation followed by condensation.

Dot and cross diagram

A drawing to show only the arrangement of the outer shell electrons or ins in a substance.

Double bond

A covalent bond made by the sharing of two pairs of electrons.

Electrolysis

The breakdown of a substance containing ions by electricity.

Electrolyte

A liquid, containing free-moving ions, which is broken down by electricity in the process of electrolysis.

Electron

A tiny particle with a negative charge. They orbit the nucleus of atoms or ions in shells.

Electronic structure

A set of numbers to show the arrangement of electrons in their shells (or energy levels). For example chlorine atoms are 2, 8, 7.

Element

A substance made up of only one type of atom. An element cannot be broken down chemically into any simpler substance.

Equilibrium

The point in a reversible reaction at which the forward and backward rates of reaction are the same. Therefore, the amounts of substances present in the reaction mixture stay constant.

Exothermic

A reaction that transfers energy to the surroundings.

Fair test

A fair test is one in which only the independent variable has been allowed to affect the dependent variable.

Fermentation

The reaction in which the enzymes in yeast turn glucose into ethanol and carbon dioxide.

Filtration

The technique use to separate substances that are insoluble in a particular solvent from those that are soluble.

Flammable

Easily ignited and capable of burning rapidly.

Fraction

Hydrocarbons with similar boiling points separated from crude oil.

Fractional distillation

A way to separate liquids from a mixture of liquids by boiling off the substances at different temperatures, then condensing and collecting the liquids.

Fullerene

Form of the element carbon that can exist as large cage-like structures, based on hexagonal rings of carbon atoms.

Giant covalent structure

A huge 3D network of covalently bonded atoms. You should know the structures of diamond, graphite and silicon dioxide

Giant lattice

A huge 3D network of atoms or ions.

Giant structure

A huge 3D network of atoms or ions.

Gradient

A measure of the slope of a straight line on a graph.

Group

All of the elements in the columns (labelled 1 to 7 and ) in the periodic table. The group number corresponds to the number of electrons in the outer shell of the atom.

Half-equation

An equation that describes reduction (gain of electrons) or oxidation (loss of electrons).

Halogens

The elements found in Group 7 of the periodic table.

Hazard

A hazard is something (e.g. an object, a property of a substance or an activity) that can cause harm.

Hydrated

Describes a substance with water in its crystals

Hydrocarbon

A compound containing only hydrogen and carbon.

Hypothesis

A proposal intended to explain certain facts or observations.

Incomplete combustion

When a fuel burns in insufficient oxygen, producing carbon monoxide as a toxic product.

Independent variable

The variable for which values are changed or selected by the investigator.

Ion

A charged particle produced by the loss or gain of electrons.

Ionic bond

The electrostatic force of attraction between positively and negatively charged ions.

Ionic Equation

An equation that shows only those ions or atoms that change in a chemical reaction.

Isotope

Atoms that have the same number of protons but different numbers of neutrons, i.e. they have the same atomic number but different mass numbers.

Law of conservation of mass

The total mass of the products formed in a reaction is equal to the total mass of the reactants.

Life cycle assessment

Carried out to assess the environmental impact of products, processes or services at different stages in their life cycle.

Line graph

Used when both variables are continuous. The line should normally be a line of best fit, and may be straight or a smooth curve.

Line of best fit

A line that represents the general trend of data. An equal number of points should be above and below the line of best fit (usually only true when dealing with a straight line).

Mass number

The number of protons plus neutrons in the nucleus of an atom.

Mean

The arithmetical average of a series of numbers.

Mixture

When some elements or compounds are mixed together and intermingle but do not react together (i.e. no new substance is made). A mixture is not a pure substance.

Mole

The amount of substance in the relative atomic or formula mass of a substance in grams.

Molecular formula

The chemical formula that shows the actual numbers of atoms in a particular molecule.

Monomers

Small reactive molecules that react together in repeating sequences to form a very large molecule - a polymer.

Neutral

A solution with a pH value of 7 which is neither acidic or alkaline.

Alternatively, something that carries no electrical charge i.e not an ion, proton or electron.

Neutralisation

The chemical reaction of an acid with a base in which a salt and water are formed. If the base is a carbonate or hydrogen carbonate, carbon dioxide is also produced in the reaction.

Neutron

A dense particle found in the nucleus of an atom. It is electrically neutral, carrying no charge.

Noble gases

The very unreactive gases found in Group 0 of the periodic table. Their atoms have very stable electronic structures (full outer shells).

Non-renewable

Something which cannot be replaced once it is used up.

Nucleus (of an atom)

The very small and dense central part of an atom that contains protons and neutrons.

Ore

Ore is rock which contains enough metal to make it economically worthwhile to extract the metal.

Oxidation

The reaction when oxygen is added to a substance/ or when electrons are lost.

Particulate

Small solid particle given off from motor vehicles as a result of incomplete combustion of its fuel.

Periodic Table

An arrangement of elements in the order of their atomic numbers, forming groups and periods.

pH

A number which shows how strongly acidic or alkaline a solution is.