CC3 & CC4

relative mass

The mass of a subatomic particle compared to the mass of a proton.

relative atomic mass (RAM)

The mean mass of an atom relative to the mass of an atom of carbon-12, which is assigned a mass of 12. The RAM of an element is the mean relative mass of the isotopes in the element.

atomic number

The number of protons in the nucleus of an atom (symbol Z). Also known as the proton number.

nucleus

The positively charged centre of an atom.

nuclear fission

The reaction in which the nucleus of a large atom, such as uranium, splits into two smaller nuclei.

subatomic particles

The smaller particles that make up atoms - protons, neutrons and electrons.

mass number

The total number of protons and neutrons in the nucleus of an atom (symbol A). Also known as the nucleon number.

electron

Tiny particle with a negative charge that is found in shells around the nucleus of an atom.

prediction

What you think will happen in an experiment and why you think this.

chemical property

How a substance reacts with other substances.

Ar

Symbol for relative atomic mass (RAM).

electronic configuration

The arrangement of electrons in shells around the nucleus of an atom.

relative charge

The electric charge of a subatomic particle compared to the charge on a proton.

relative atomic mass, Ar

The mean mass of an atom relative to the mass of one-twelfth of an atom of carbon-12, which is assigned a mass of 12. The Ar of an element is the mean relative mass of the isotopes in the element.

inert

Does not react.

physical property

A description of how a material behaves and responds to forces and energy. Hardness is a physical property.

period

A horizontal row in the periodic table.

proton

A positively charge subatomic particle in the nucleus of all atoms.

element

A simple substance made up of only one type of atom.

group

A vertical column of elements in the periodic table. Elements in the same group generally have similar properties.

mean

An average calculated by adding up the values of a set of measurements and dividing by the number of measurements in the set.

electron shell

Areas around a nucleus that can be occupied by electrons, usually drawn as circles. Also called an electron energy level.

atom

Atoms are small particles from which all substances are made. They are the smallest neutral part of an element that can take part in chemical reactions.

isotopes

Atoms of an element with the same number of protons (atomic number) but different mass numbers due to different numbers of neutrons.

periodic table

Chart in which the elements are arranged in order of increasing atomic number.

neutron

Electrically neutral subatomic particle found in the nucleus of most atoms.

X-ray

Electromagnetic radiation that has a shorter wavelength than UV but longer than gamma rays.