Chemistry- Atoms, molecules and stoichiometry

define the unified atomic mass unit

one twelfth of the mass of carbon 12 atom

define relative atomic mass

the average weighted mass of atoms in a given sample of an element compared to the value of of the unified atomic mass unit

relative atomic mass of x equation

avg. mass of one atom of x / 1/12 of the mass of one carbon

define 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

basically the same the relative molecular mass but this is used for ions

define empirical formula

a formula that shows the simplest whole number ratio of atoms present

define molecular formula

a formula that shows the exact number of atoms of each element present in a molecule of the compound

formula for silver (1)

Ag⁺

formula for ammonium

NH₄⁺

formula for Zinc(II)

Zn²⁺

formula for hydroxide

OH^–

formula for nitrate

NO₃^–

formula for sulfate

SO₄^2–

formula for carbonate

CO₃^2–

formula for hydrogen carbonate

HCO₃^–

formula for phosphate

PO₄^3–

define oxidation number

a number given to an atom or ion compound that describes how oxidised or reduced it is

define an anhydrous compound

a compound that doesn’t contain water of crystallisation

define hydrated compound

a compound that contains water of crystallisation

define water of crystallisation

the fixed, stoichiometric amount of water chemically bonded within a crystal lattice

what is the easiest way to work out an anhydrous compound using a hydrated compound (formulaically) considering this to be a possible step in an exam question

calculate by removing the water from it’s formula

what is the percentage yield formula

actual yield/predicted yield multiplied by 100

what is the easiest way to identify a limiting reagent from equation

divide it’s number of moles (whether this is given or worked out) by the coefficient ratio