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Key Chemistry terms

All those terms you might want to know, just for reference that is.

Amount of substance-The means of counting atoms within a mole.
Anhydrous-Lacking water molecules.
Atomic number-The number of protons in an atom.
Atomic orbitals-A region within an atom that can hold up to two electrons with opposite spins.
Avogadro constant-The number of atoms per mole of the carbon 12 isotope (6.02x10 to the power of 23 mol -1)
Compound-A substance formed from two or more chemically bonded elements.
Dative bond-A shared pair of electrons which have been provided by one of the bonding atoms.
Electronegativity-A measure of the attraction of a bonded atom for the pair of electrons in a covalent bond.
Electron shielding-The repulsion between electrons in different inner shells.
Empirical formula-Whole number ratio of atoms of each element in a molecule.
First ionisation energy-The energy required to remove one electron from the outer shell of an element.
Hydrogen bond-A strong dipole-dipole attraction between : An electron deficient hydrogen atom and a lone pair of electrons on a highly electronegative atom on a different molecule.
Hydrous-containing water molecules.
Intermolecular force-An attractive force between neighbouring molecules
Ions-A positively or negatively charged atom or group of atoms.
Isotopes-Atoms of the same element but with a different number of neutrons.
Mass number-The number of particles (protons and neutrons) in the nucleus.
Molar mass-The mass per mole of a substance (g-mol-1)
Molar volume-The volume per mole of gas.
Mole-The amount of any substance containing as many particles as there are carbon atoms in exactly 12g of carbon-12.
Molecular formula-The actual number of atoms of each element of a molecule.
Molecule-A small group of atoms held together by a covalent bond.
Polar bond-Has an overall dipole, when you take into account any dipoles across the bonds.
Permanent dipole-A small charge difference across a bond that results from a difference in the electronegativity of the bonded atoms.
Permanent dipole dipole-A weak attractive force between permanent dipoles across neighbouring polar molecules
Relative atomic mass-The weighted mean mass of a singular atom compared to 1/12 of carbon-12.
Relative molecular mass-The weighted mean mass of a molecule compared to 1/12 of carbon-12.
Relative isotopic mass-The mass of an atoms isotope compared with 1/12 of an atom of carbon-12.
Shells-A group of atomic orbitals.
Sub-shell- A group of the same type of atomic orbitals in a shell.
Successive ionisation energies-The measure of energy required to remove each electron in turn.
Van der Waals' forces-Attractive force between induced dipoles in neighbouring molecules.
Waters of crystallisation-Water molecules that forms part of the crystalline structure of a compound.

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