Topic 2 Definitions

Question 1

anhydrous

Answer 1

a substance, especially a crystalline compound containing no water

Question 2

hydrated

Answer 2

a substance that contains water

Question 3

waters of crystallisation

Answer 3

water that is chemically bonded into a crystal structure

Question 4

mole

Answer 4

base unit amount of substance

Question 5

empirical formula

Answer 5

simplest whole no. ratio of atoms of each element into a compound

Question 6

molecular formula

Answer 6

the no. & type of atoms of each element in a molecule

Question 7

molar mass

Answer 7

mass in grams of 1 mole of a substance

Question 8

molecular gas volume

Answer 8

the volume of one mole of any gas at room temperature and pressure (24dm³)

Question 9

mass spectronomy

Answer 9

analytical technique for identifying chemical constitution of a substance by separating its gaseous ions according to their mass

Question 10

relative molecular mass

Answer 10

average mass of a molecule relative to the mass of 1/12 of a carbon -12 atom

Question 11

relative formula mass (Mr)

Answer 11

sum of the relative atomic masses of atoms in a molecule in the quantities shown in the molecular formula

Question 12

isotopes

Answer 12

atoms of the same element with a different no. of neutrons and different masses

Question 13

relative isotopic mass

Answer 13

the mass of an isotope compared to the mass of 1/12 of the mass of carbon - 12 atom

Question 14

Avogadro constant

Answer 14

the no. of particals per mole (6.02X10³)

Question 15

average bond enthalpy

Answer 15

enthalpy change happens when 1 of the bonds break in gaseous molecules. Used to measure the strength of covalent bonds