AS Chemistry - Key Words!

Emily S By Emily S, 6th Jan 2013 | Follow this author | RSS Feed | Short URL
Posted in Wikinut>Writing>Essays

This article will give you lots of definitions to words that you will need to know for AS Chemistry!


Atoms that are a variation of the same element with different numbers of neutrons but the same number of protons.

An atom (or covalently bonded molecule) with a positive or negative charge due to the loss or gain of electrons.

Mass Number/Atomic Mass
The overall number of protons/neutrons contained in the nucleus of an atom.

Relative Molecular Mass (Mr)
The weighted mass of a molecule compared with 1/12 of the mass of a Carbon-12 atom. It is found by combining the atomic masses of all the elements in a molecule.

Molar Mass
The mass per mole of a substance.


A small group of covalently bonded atoms.

The molecular weight of a substance in grams.

Empirical Formula

The simplest ratio of atoms in a compound.

Molecular Formula
The actual number of atoms in a molecule.

The amount of solutes, per 1dm^3, dissolved in a solution.

A proton donor.

A proton acceptor.

Molar Volume
The volume of a gas per mole.

A substance that has no water molecules.

A compound with the structure and form of a crystal.

Water of Crystallisation
Water molecules that form part of the crystalline structure of a compound.

Loss of electrons.

Gain of electrons.

First Ionisation Energy
The amount of energy needed to remove one electron from each one mole of gaseous atoms to form one mole of gaseous 1+ ions.

Electron Shielding
The repulsion that occurs between electrons in the different inner shells of an atom.

Atomic Orbital
A region within an atom that can hold up to 2 electrons that are both moving in opposite directions.

A group of the same type of atomic orbitals.

Electron Configuration
The way that atoms are arranged in an atom.


A Levels, Chemistry, Definitions, Key Words, Revision

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author avatar Md Rezaul Karim
13th Jan 2013 (#)

Great work to share. Thanks

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