bonding & moles

Question 1

how to calculate the mass of a molecule

Answer 1

mass = mole x RFM

Question 2

how to calculate the RFM of a molecule?

Answer 2

adding up the atomic masses of all the atoms in a molecule or formula unit

Question 3

how to calculate moles?

Answer 3

Moles = mass / RFM

Question 4

how to calculate the ratio of a molecule?

Answer 4

e.g. C3H6
3:6 –> 1:2
CH2

Question 5

Can you draw a dot-cross diagram (covalent bonding)?

Question 6

describe the properties of diamond

Answer 6

Sublimes at a very high temperature - covalent bonds are very strong, lots of bonds in a giant lattice, lots of energy required to break all the bonds
Hard - used in cutting
Cannot conduct electricity - no freely moving charged particles, all atoms are neutral, all electrons are stuck inside an atom or a bond

Question 7

describe the properties of graphite

Answer 7

Sublimes at a very high temperature - covalent bonds are very strong, lots of bonds in a giant lattice, lots of energy required to break all the bonds
Soft + slippery - layers can slide easily so it is used as a solid lubricant
Conducts electricity - inside the layers, the delocalised electrons cn move freely

Question 8

properties of ionic compounds

Answer 8

high melting point
soluble in water
electrical conductor

Question 9

describe the properties of simple molecular covalent substances?

Answer 9

low boiling points - weak intermolecular forces between the molecules, not a lot of energy needed to overcome the bonds
do not conduct electricity - molecules are neutral