CH-17 Solid liquids and gases

Matter - Anything that occupies space and has mass.

Evaporation - The changing of a liquid to a gas.

Condensation - The changing of a gas back into its liquid state.

Diffusion - The movement of particles from an area of high concentration to an area of low concentration.

Solids - Particles are closely packed together, don’t move but can vibrate, have a definite volume and shape.

Liquids - Particles are close to each other but are free to move around, they have a definite volume but their shape can change.

Gases - Particles are free to move in all directions, they don’t have a definite shape or volume and spread out to fill a container they're placed in, and they can be compressed easily since they’re spread out.

CH-18 Solutions and Crystallisation

Crystallisation - The formation of crystals by cooling a saturated solution.

Solute - The substance being dissolved.

Solvent - The liquid the solute is dissolving in.

Solution - The solute and the solvent.

Soluble - The ability to for a substance to dissolve in a solvent.

Insoluble - A substance that can’t dissolve.

Solubility - How much will dissolve.

Concentrated solution - A large amount of solute in a small amount of solvent.

Saturated solution - A solution that contains as much dissolved solute as possible at that temperature.

CH-19 Separating mixtures

Mixture - Consists of two or more substances mingled together but not chemically combined.

Filtering - Used to separate an insoluble solid from a liquid.

Evaporation - Used to retrieve a solute from a solution.

Distillation - Used to separate substances that have different boiling points.

Chromatography - Used to separate a mixture of substances which are in a solution.

CH-20 Elements, compounds and mixtures

An element - A substance made up of only one type of atom.

A molecule - Composed of two or more atoms chemically combined.

Compounds - Consist of two or more elements chemically combined.

CH-21 The atom

An atom - The smallest part of an element which still has the properties of that element.

Atomic number - The number of protons in an atom of that element.

The mass number - The total number of protons and neutrons in an atom of that element.

Isotopes - Atoms of the same element which have different numbers of neutrons.

Protons - Positive and found in the nucleus.

Neutrons - Neutral and found in the nucleus.

Electrons - Negative and orbit the nucleus.

CH-22 The periodic table

The periodic table - Show the elements in order of increasing atomic numbers.

Groups - Vertical columns of elements.

Periods - Horizontal rows of elements in the periodic table.

CH-23 Chemical bonding

An ionic bond - The force of attraction between oppositely charged ions in a compound.

An ion - A Charged atom or group of atoms.

A covalent bond - Formed when electrons are shared between non-metal atoms.

CH-24 Metals and non-Metals

Alloy - A mixture of metals.

Rusting - The corrosion of iron.

Metals - Hard, dense, shiny, have high melting points, good conductors, malleable, ductile and sonorous.

Non-Metals - Usually opposite to metals.

CH-25 Fuels

Fuels - A substance that burns in oxygen to produce heat.

Fossil fuels - Formed from the remains of organisms that lived millions of years ago.

Hydrocarbons - Compounds made up of hydrogen and carbon.

CH-26 Acids and Bases

Acids - Have a PH less than 7, sour taste and turn blue litmus red.

Bases - Have a PH greater than 7, tastes bitter and turns red litmus blue.

Alkali - A base that is soluble in water.

The PH scale - A measure of acidity or basicity, running from 0 to 14.

Neutral substance - PH of 7, eg. Water.

Titrations - A way of neutralising a base and acid restoring the balance.

CH-27 The Atmosphere

Catalysts - Substances that alter the rate of a chemical reaction but are not used up themselves by allowing particles with less energy an alternative path with a lower activation energy.

Air - Contains 78% nitrogen, 21% oxygen, CO2 and water vapour.

CH-28 Water

Electrolysis - The splitting up of a compound by passing electricity through it.

The meniscus - The curved surface of a liquid in a vessel.

Water - A compound made up of hydrogen and oxygen.

Desalination - A process that obtains freshwater from seawater(saltwater).

CH-29 Water Hardness

Hard water - Does not lather easily with soap and contains calcium and magnesium ions.

Soft water - Lathers easily with soap.

CH-30 Plastics

Polymerisation - Small repeating units called monomers join together to form a larger molecule called a polymer.

Plastics - Man-made materials, mostly from crude oil.

Fractional distillation - Separates various hydrocarbons found in crude oil.

Non-Biodegradable - They remain intact for long periods of time.

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This is the list of Junior Cert Chemistry keywords in a table format.