Atomic and Electronic Structure Overview

Mass number (RAM) (A)

The total number of protons and neutrons in an atom

Atomic number (Z)

The number of protons in an atom

Isotope

Atoms of the same element with different mass numbers

Ion

A species in which there is a surplus of lack of electrons

First ionisation energy

The amount of energy required to remove the outermost electrons from a gaseous atom in its ground state

Valence electrons

The electrons in the outer energy level

Mole

The amount of any substance that contains the same number of elementary particles as 12g of Carbon-12

Relative atomic mass

The average mass of one atom of an element, relative to carbon-12 which has mass exactly 12

Relative molecular mass

The average mass of one molecule relative to Carbon-12, which has mass exactly 12

Law of Conservation of Matter

Matter cannot be created or destroyed, only transferred from one place to another

Molar mass

The mass in grams of one mole of that substance

Empirical formula

The formula that shows the simplest ratio of elements of the compound

Molecular formula

The formula that shows the actual ratio of elements in a compound

Standard solution

A solution of which the concentration is known exactly, and is unlikely to change for a period of time

Solution

A homogenous mixture of a solute and solvent

Solute

The substance that is dissolved in the solution

Solvent

The substance in which another substance is dissolved, forming a solution

Concentration

The amount of solute per unit volume of solutions

Ionic Bond

A transfer of electrons and subsequent electrostatic attraction

Covalent Bond

The sharing of at least one pair of electrons between two atoms

Electronegativity

A measure of the tendency of an atom to attract a bonding pair of electrons

Non-Polar covalent

An equal sharing of electrons

Polar covalent

An unequal sharing of electrons leading to a dipole forming (as a result of electronegativity difference)

Intermolecular forces

The weak force of attraction between molecules, ions or atoms in noble gases

Intra-molecular bond

A bond which occurs between atoms within a molecule

Giant covalent substance

A substance which contains a large network of covalent bonds

Allotrope

Different structural forms of the same element

Metallic bond

Bond between a positive kernel and a sea of delocalised electrons

Decomposition

Molecules or compounds break down into two or more than two simpler chemically new substances

Electrolysis

The process of passing an electric current through a substance to chemically decompose it

Electrolyte

A substance that can conduct electricity by forming free ions when molten or dissolved in solution

Electrode

A conductor through which electricity enters or leaves a substance

Oxidation

The loss of electrons

Reduction

The gain of electrons

Redox reaction

A reaction involving the transfer of electrons

Oxidising agent

A substance that accepts electrons

Reducing agent

A substance that donates electrons

Spectator ion

An ion that is unchanged by a chemical process

Anode

The electrode where oxidation takes place

Cathode

The electrode where reduction takes place

Combination

Two or more molecules are combined together chemically to form a new substance

Organic molecules

Molecules containing carbon atoms with the exception of carbon dioxide, carbon monoxide, diamond, graphite, carbonates, carides and cyanides

Hydrocarbons

Compounds that contain only carbon and hydrogen

Homologous series

A series of similar compounds with the same functional group and have the same general formula, in which each differs from the previous one by a single CH2 unit