Unit 1 Definitions Flashcards
Relative isotopic mass
The mass of an atom of an isotope compared with one-twelfth of the mass of an atom of Carbon-12.
Isotopes
Elements which have gained or lost neutrons, but have the same number of protons.
Relative atomic mass
The weighted mean mass of an atom of an element compared with one-twelfth of the mass of an atom of Carbon-12. NO UNITS!
Relative molecular mass
The weighted mean mass of a molecule compared with one-twelfth of the mass of an atom of Carbon-12.
Relative formula mass
The weighted mean mass of a formula unit compared with one-twelfth or the mass of an atom of Carbon-12.
First ionisation energy
The energy required to remove one electron from every atom or a mole of atoms in the gaseous state.
Oxidising agent
Makes something else oxidise
Reducing agent
Makes something else reduce
Acid
An acid released H+ ions in aqueous solution. An acid is a proton donor.
Base
Bases are proton acceptors.
Alkali
An alkali is a soluble base that releases OH- ions in water.
Salt
Salts are ionic compounds formed when the H+ ions in acids are replaced by metal ions or ammonium ions.
Amount of substance
The quantity whose unit is the mole.
Mole
The amount of any substance containing as many particles as there are Carbon atoms in exactly 12g of the carbon -12 isotope.
Avogadro Constant
The number of atoms per mole of Carbon-12 isotope, 6.02x10^23 mole^-1
Molar mass
The mass per mole of a substance in g/mol
Empirical formula
The simplest whole number ratio if the atoms of each element in a compound.
Molecular formula
The actual number of atoms of each element in a molecule.
Anhydrous
A substance containing no water molecules.
Hydrated
Crystalline and containing water molecules.
Water of crystallisation
Water molecules that form an essential part of the crystalline structure of a compound.
Molar gas volume
The volume occupied by one mole of a gas with units dm^3/mol^-1
At rtp, one mole of gas occupies 24dm^3.
Ionic bonding
The electrostatic attraction between oppositely charged ions.
Covalent bond
A bond formed by a shared pair of electrons.
Dative covalent bond
A shared pair of electrons which had been provided by one of the bonding atoms only.
Metallic bonding
The electrostatic attraction between positive metal ions and delocalised electrons.
Van Der Waals’ forces
Attractive intermolecular forces that act between non-polar molecules.
Electronegativity
The ability of an atom to attract the bonding electrons in a covalent bond.
Permanent dipole
A small charge difference across a bond that results from a difference in electronegativities of the bonded atoms.
Polar covalent bond
A bond with a permanent dipole
Polar molecule
A molecule with an overall dipole
Hydrogen bond
The attraction between a hydrogen atom bonded to a nitrogen, fluorine or oxygen atom and a lone pair on another nitrogen, oxygen or fluorine atom.
