Definitions (Understand) Flashcards
Ion
a positively or negatively charged atom or (covalently bonded) group of atoms (a molecular ion).
Atomic number
the number of protons in the nucleus of an atom
Relative formula mass
the weighted mean mass of a formula unit compared with one-twelth of the mass of an atom of carbon 12
Relative molecular mass
the weighted mean mass of a molecule compared with one-twelfth of the mass of an atom of carbon-12.
Mole
the amount of substance containing as many particles as there are carbon atoms in exactly 12g of carbon-12 isotope
Molar mass
The mass of one mole of any substance, expressed in grams per mole.
Empirical formula
the simplest whole number ratio of atoms of each element in a compound
Molecular formula
the 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.
Lone pair
an outer-shell pair of electrons that is not involved in chemical bonding
Bonded pair of electrons
A pair of electrons shared between two atoms to make a covalent bond.
Permanent dipole
a small charge difference across a bond resulting from a difference in the electronegativities of the bonded atoms
Polar bond
A covalent bond with a permanent dipole
Polar molecule
a molecule with an overall dipole, taking into account any dipoles across bonds
Alkyl group
an alkane with a hydrogen atom removed, e.g. CH3, C2H5; alkyl groups are often shown as R
Alicyclic
Contains carbon atoms joined together in a ring that is not aromatic.
Aliphatic
Contains carbon atoms joined together in straight or branched chains.
Aromatic
Containing one or more benzene rings