PMT Defintions

Alkali metals

The elements in group 1 of the periodic table

Atom

The smallest part of an element that can exist. All substances are made up of atoms

Atomic nucleus

Positively charged object composed of protons and neutrons at the centre of every atom with one or more electrons orbiting it

Atomic number

The number of protons in the nucleus

Chromatography

A separation technique used to separate a mixture of chemicals by distributing the components between two phases

Compound

A substance made up of two or more types of atoms chemically combined together

Crystallisation

A separation technique used to produce solid crystals from a solution by evaporating the solvent

Displacement

A chemical reaction in which a more reactive element displaces a less reactive element from its compound

Electron

Negatively charged subatomic particle which orbit the nucleus at various energy levels

Electron shell

Different energy levels in atoms occupied by electrons

Element

A substance made up of only one type of atom

Filtration

A separation technique used to separate solids from liquids

Fractional distillation

A method of separating a mixture of substances according to their different boiling points

Group (periodic table)

The columns of the periodic table represent different groups of elements

Elements with similarity properties in the same group

Halogens

The elements in group 7 of the periodic table

Ion

An atom or molecule with an electric charge due to the loss or gain of electrons

Isotope

Atoms of the same element wjth the same number of protons but a different number of neutrons

Mass number

The total number of protons and neutrons in the nucleus

Metals

Elements that react to form positive ions

Found to the left and towards the bottom of the periodic table

Mixture

Consists of two or more elements or compounds not chemically combined together

Neutron

Neutrally charged subatomic particle present in the nucleus of the atom

Relative mass of 1

Noble gases

The elements in group 0 of the periodic table

Non metals

Elements that react to form negative ions

Found towards the right and top of the periodic table

Nucleur model

The nuclear atomic model stated that the mass was concentrated at the centre of the atom and the nucleus was charged

Periodic table

Table of elements arranged in order of atomic number and such that elements with similair properties are in the same column (group)

Plum pudding model

Atomic model devised after the discovery of the electron

The model suggested the atom is a hall of positive charge with negative electrons embedded through it

Proton

Positively charged subatomic particle present in the nucleus of the atom.

Relative mass of 1

Relative atomic mass

An average value that takes account of abundance of the isotopes of the element

Simple distillation

A procedure by which two liquids with different boiling points can be separated

Transition metals

The collection of metallic elements midway through the periodic table