Y7 - Science - Chemistry

Matter

The material from which things are made up from. Takes up space. Can exist as a solid, liquid, or gas

Solid

Have a fixed volume and cannot be compressed.

Liquid

Has a fixed volume, but doesn’t have a fixed shape

Gas

No fixed volume or shape.

Particle Model

A scientific theory that explains the properties of solids, liquids and gases by suggesting that all matter is made of particles, and that those particles behave differently in solids, liquids, and gases.  

Evaporation

Liquid turns into a gas. Increase in temperature.

Condensation

Gas turns into liquid. Decrease in temperature.

Melting

Solid turns into liquid. Increase in temperature.

Freezing

Liquid turns into solid. Decrease in temperature.

Density

The measurement of quantity or mass per unit of volume in a particular substance.

Mass ➗ Volume

Melting Point

The temperature at which a given solid will melt

Compressibility

The capacity of something to be flattened or reduced in size by pressure.

Boiling point

The temperature at which a liquid changes into a gas

Pure substance

Made from only one chemical element or one compound.

Sublimation

When a solid turns into a gas

Deposition

When a gas turns into a solid

Atom

The basic building blocks of matter that retains its properties

Element

Any substance that cannot be decomposed into simpler substances by ordinary chemical processes. The fundamental materials of which all matter is composed.

Compound

A material formed by chemically bonding two or more different chemical elements

Impure Substance

A substance made from more than one element or one compound

Pure substance

Made up of only one type of particle (atom, molecule, or compound)

Proton

A subatomic particle. Has a positive electric charge. Found in the nucleus

Neutron

A subatomic particle. A neutral (no charge) electric charge. Found in the nucleus of all atoms except Hydrogen.

Nucleus (of an atom)

Consisting of protons and neutrons at the center of an atom.

The nucleus is positively charged, due to the fact that there are no electrons in it.

Electron

Subatomic particle. Negative electric charge. Found orbiting the nucleus in shells. Add very little mass to the atom.

The Periodic Table

A display of elements ordered according to their atomic number. It orders elements into rows and columns based on their properties. 

Groups

Vertical columns numbered 1-18 of the periodic table. Helps to determine the number of valence electrons of an element’s atom.

Periods

The horizontal rows of elements. Represent the number of electron shells an atom has.

Metals

Found on the left-hand side of the Periodic table and account for the majority of the known elements.

Having a luster (shiny). 

Being malleable in their solid state. In other words they can be bent into shape. Gold is the most malleable of all the metals

Ductile – can be drawn into a wire. Silver is one of the most ductile metals

Able to conduct heat and electricity

Most metal’s have high boiling points

Usually more dense than non-metals

(Most are) Silvery in colour, although some like gold, cesium and copper are coloured.

Non-Metals

Found on the far right side of the Periodic table. Most are either gases or solid, with the exception of bromine, which is a liquid. Non-metals have the properties:

Dull (not shiny)

Brittle (therefore can’t bend and will break instead)

Poor conductors of heat and electricity

Lower melting and boiling points than metals

Metalloids

Small group of elements that are found in between the metals and non-metals.

Dull or lustrous

Semiconductors of electricity

Brittle

They are Silicon and Boron.

Atomic Number

Represents the number of protons that element has in its nucleus.

Atomic mass

The average mass of the atom’s element measured in atomic mass unit (amu).

Protons + Neutrons

Mixture

Otherwise known as an impure substance, it contains two or more substances that are not chemically combined.

Solution

Homogeneous mixture of one or more solutes dissolved in a solvent.

Solute

The substance that dissolves in a solvent to produce a homogeneous mixture.

E.g. The salt being placed in water to make salt water

Solvent

Any substance, usually liquid, capable of dissolving one or several substances, thus creating a solution.

Solubility

Defined as the maximum amount of a substance that will dissolve in a given amount of solvent at a specified temperature.

Soluble

When it is capable of being dissolved in some solvent (usually water)

Insoluble Substance

A substance (solid) that will not dissolve in a solvent even after mixing

Concentration

The amount of a substance in a given amount of another substance

Dilute (solution)

Which there is a relatively small amount of solute dissolved in the solution

Supersaturated solution

A solution that contains more than the maximum amount of solute that is capable of being dissolved at a given temperature.