chemistry c3

conservation of mass

no atoms are lost or made during a chemical reaction, mass of products = mass of reactants

overall charge of an ionic compound

has to be none since the positive and negative charges balance each other out

relative atomic mass

average mass of the isotopes of that element weighted to take into account the abundance of each isotope

why do some reactions seem to involve a change in mass

a reactant or product is a gas and has escaped

uncertainty

range of measurements each side of the mean

how to calculate uncertainty

half of the range

mole

6.02 × 10²³ atoms or molecules or ions of any substance

the mass of one mole of a substance

is equal to its relative formula mass/atomic mass in grams

mole equation

mole = mass (g) / relative atomic or formula mass