definitions

Question 1

Define the empirical formula

Answer 1

the simplest whole number ratio of the different
atoms or ions in a compound

Question 2

Define isotopes

Answer 2

isotopes as different atoms of the same
element that have the same number of protons
but different numbers of neutrons

Question 3

why do isotopes have the same chemical properties

Answer 3

isotopes of the same element have
the same chemical properties because they have
the same number of electrons and therefore the
same electronic configuration

Question 4

Define the molecular formula of a compound

Answer 4

the number and type of different atoms in one
molecule

Question 5

Define relative molecular mass, Mr

Answer 5

the sum of of the relative atomic masses of a compound

Question 6

what is meant by a mole

Answer 6

the unit of amount of
substance and that one mole contains
6.02 × 1023 particles, e.g. atoms, ions, molecules;
this number is the Avogadro constant

Question 7

enthalpy change

Answer 7

the transfer of thermal energy during a
reaction
- ∆H is negative for exothermic reactions
and positive for endothermic reactions