Unit 2 - Atoms, Molecules and Stoichiometry Flashcards
Define unified atomic mass unit
One twelth of the mass of a carbon-12 atom
Define relative atomic mass
The weighted average mass of atoms in a given sample of an element compared to the value of the unified atomic mass unit
Define relative isotopic mass
The mass of a particular atom of an isotope compared to the value of the unified atomic mass unit
Define relative molecular mass
The weighted average mass of a molecule in a given sample of that molecule compared to the value of the unified atomic mass unit
Define relative formula mass in terms of the unified atomic mass unit
The weighted average mass of one formula unit compared to the value of the unified atomic mass unit
Define formula unit
The simplest formula for a covalent giant structure or ionic giant structure e.g SiO₂ or MgCl₂
What is water of crystallisation
A specific number of moles of water associated with a crystal structure
What does anhydrous mean
A crystal structure which contains no water of crystallisation
Define the mole
The amount of substance which contains 6.02x10²³ specified particles (Avagadro’s number)
What is molar mass
The mass of a mole of substance in grams
Define empirical formula
The simplest whole number ratio of the elements present in one molecule or formula unit of the compound
Define molecular formula
The formula which shows the number and type of each atom in a molecule
What are spectator ions?
Ions present in a reaction micture which do not take part in the reaction
Define solute
A substance which dissolves in a solvent to form a solution
Define solvent
A substance which dissolves a solute to form a solution
