Science - Ions and Isotopes

Year 9

atom

smallest possible unit into which matter can be divided, while still maintaining its properties.

proton

positively charged subatomic particle found in the nucleus of an atom

neutron

neutral particle found in the nucleus of an atom, contributing to its mass but not its charge.

electron

negatively charged subatomic particle orbiting the nucleus of an atom

Atomic mass number (A)

the total number of protons and neutrons in an atomic nucleus, determining the mass of the atom.

Atomic number (Z)

the number of protons in the nucleus of an atom, determining the elements identity

Isotope

Atoms of the same element that have a different numbers of neutrons, but the same number of protons and electrons

Radioisotope

When isotopes have too many or too few neutrons to maintain its stability, the atom decays and produces radiation

Radioactive decay

The process where an unstable nucleus loses energy by radiations, becoming more stable

lon

an atom or molecule with a net electric charge due to the loss or gain of one or more electrons

Cation

a positively charged ion formed when an atom loses one or more electrons.

Anion

a negatively charged ion, formed when an atom gains one or more electrons.

lonic compound

when cations and anions come together

Valence Shell

Outermost electron shell of an atom

Valence Electrons

Electrons in the outermost shell of an atom that determine its bonding properties.

Octet rule

the tendency of atoms to prefer to have eight electrons in the valence shell

Electrostatic attraction

Things with opposite electric charges are attracted to each other.

Half-life

the time it takes for half of the radioactive substance in a sample to decay

Alpha decay

When a high mass atom has too many protons - making it unstable - it will reduce its size through alpha decay

Beta decay

When an atom has too many neutrons compared to its protons it will undergo beta decay and release a beta particle.

Gamma decay

the release of pure energy (electromagnetic radiation).