Definitions Flashcards
Define the atomic number
The number of protons
Define an isotope
Atoms of the same element with the same numbers of protons but different numbers of neutrons and masses.
Define the mass number (on periodic table)
The number of protons + the number of neutrons
Define an ion.
A charged atom
Define a cation
A positive ion - atoms with fewer electrons than protons
Define an anion
A negative ion - atoms with more electrons than protons
Define the relative isotopic mass
The mass of an isotope relative to 1/12th of the mass of an atom of carbon-12.
Define the relative atomic mass Ar
The weighted mean mass of an atom of an element relative to 1/12th of the mass of an atom of carbon-12.
Define a binary compound
Contains 2 elements only
Define a polyatomic ion
An ion that contains more than 1 element bonded together
Define a diatomic molecule
2 of the same atoms bonded together e.g. O2,Cl2
Define the formula unit
In ionic compounds, the formula worked out from the ionic charges that are used in equations
Define avogadros constant
6.02 x 10^23 mol^-1
The number of particles in each mole of carbon-12
Define molar mass
The mass per mole of a substance in units of g mol^-1
Define the molecular formula
The number of atoms of each element in a molecule
Define the empirical formula
The simplest whole-number ratio of atoms of each element in a compound.
Define the relative molecular mass Mr
Compares the mass of a molecule with the mass of an atom of carbon-12
Define the relative formula mass
Compares the mass of a formula unit with the mass of an atom of carbon-12
Define hydrated
A crystalline compound containing water molecules
Define the water of crystallisation
Water molecules that are bonded into a crystalline structure structure of a compound.
Define anhydrous
Containing no water molecules
Define standard solution
A solution of known concentration
Define molar gas volume
The volume per mole of gas molecules at a stated temperature and pressure.
Define limiting reagent
The reactant that is not in excess and is used up first and stops the reaction.