Chemistry - Atomic Structure C1 - definitions

Aqueous solution

The mixture made by adding a soluble substance to water

Atom

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

Atomic Number

The Number of Protons in an atom

Balanced Symbol Equation

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

Biofuel

Fuel made from animal or plant products

Chromatography

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

Compound

A substance made when 2 or more elements are chemically bonded together

Electron

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

Electronic Structure

A set of numbers to show the arrangement of electrons in their shells

Element

A substance that is made of one type of atom. It cannot be broken down chemically into any simpler substance

Group

All the elements in the columns of the periodic table

Ion

A charged atom produced by the loss or gain of electrons

Isotope

Atoms that have the same number of protons but different number of neutrons

Law of Conservation of mass

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

Mass number

The number of protons plus number of neutrons of an atom

Neutron

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

Nucleus (of an atom)

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

Periodic Table

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

Product

A substance made as a result of a chemical reaction

Proton

A tiny positive particle found inside the nucleus of an atom

Reactant

A substance we start with before a chemical reaction takes place

Shell

An area in an atom, around its nucleus, where electrons are found

State symbol

The abbreviations used in balanced symbol equations to show if reactants and products are solid (s), liquid (l), gas (g) or dissolved in water (aq)

Symbol equation

an equation that helps you see how much of each substance is involved in a chemical reaction by showing the chemical symbols and formulae of all the reactants and products involved

Word equation

A way of describing what happens in a chemical reaction by showing the names of all reactants and the products they form

Periodic Table

A table containing all of the chemical elements

Element

A pure substance made up of one type of atom

Control Variable

The variable that stays the same in an investigation

Compound

Different atoms which are chemically joined together. They must contain 2 or more different types of elements

Law of Conservation of Mass

The total mass of the products formed in a chemical reaction is equal to the total mass of the reactants because no atoms are lost or made in a chemical reaction

Fractional Distillation

A method used to separate many liquids with similar boiling points

Filtration

Where Insoluble solids are separated from liquids

Simple Distillation

Technique used to separate 2 liquids with different boiling points

Fractionating Column

Apparatus for separating many liquids with similar boiling points

Miscible

Liquids that dissolve in eachother and mix completely

Condenser

Apparatus that cools a gas down and turns it into a liquid

Crude Oil

A mixture of different hydrocarbons. It must be separated into different substances before we can use it. These substances have similar boiling points and are called Fractions

Fraction

A set of hydrocarbon molecules of similar size and boiling points

Isotopes

Atoms of the same element that contain the same number of protons and electrons but a different number of neutrons

Ion

A charged atom created when an atom loses or gains electrons. It becomes positive or negative

Relative Mass

The average mass of an elements atoms

Mixture

In a mixture there are no chemical bonds, so the elements are easy to separate. Examples of this is air and salt water

Chromatography

To separate out mixtures

Evaporation

To separate a soluble salt from a solution; a quick way of separating out the salt

Crystallisation

To separate a soluble salt from a solution; a slower method of separating out salt