C1 Key concepts in chemistry

Question 1

What is the formula for moles?

Answer 1

moles = mass/ molar mass

Question 2

What is Avogadros constant?

Answer 2

6.02 x10^23

Question 3

What is the order of prioritisation when balancing equations?

Answer 3

• metals
• non metals
• hydrogen
• oxygen

Question 4

What is the test for hydrogen?

Answer 4

• lighted splint

- squeaky pop

Question 5

What is the test for oxygen?

Answer 5

• glowing splint

- re ignites

Question 6

How do you find the relative formula mass of compounds?

Answer 6

atomic mass x number of element

eg. CH4

1 carbon, atomic mass of 12
4 hydrogen, atomic mass of 1

(1x12) + (4x1) = 16

Question 7

What is an ionic bond?

Answer 7

a bond that involves the electrostatic attraction between oppositely charged ions

between a none metal and metal
transfer of electrons

Question 8

properties of ionic compounds:

Answer 8

• conduct electricity when molten/dissolved but NOT when solid
• very high melting/boiling point due to strong electrostatic forces
• metal and non metal

Question 9

properties of simple covalent molecules:

Answer 9

• non metals
• joined by strong covalent bonds but weak intermolecular forces
• low melting and boiling points
• usually gas at room temperature
• do not conduct electricity

Question 10

properties of diamond:

Answer 10

• giant covalent molecule
• giant 3D lattice
• each carbon atom bonded to 4 others
• very high boiling and melting point due to 4 strong covalent bonds on each carbon atom
• doesn’t conduct electricity due to no free electrons

Question 11

properties of graphite:

Answer 11

• giant 3D covalent
• each carbon covalently
  bonded to 3 others in layers
• weak intermolecular forces hold the layers together
• high melting/boiling point
• conducts electricity due to delocalised pool of electrons which can carry charge
• layers slide over each other making a great lubricant

Question 12

properties of fullerene:

Answer 12

• hollow molecules
• conducts electricity
• e.g. nanotubes, buckminsterfullerene
• used as catalysts due to large surface area
• used as medicine cages
• nanotubes strengthen other materials because they don’t break when stretched and add little weight

Question 13

moles formula

Answer 13

moles = mass / Mr

atoms = moles x avogadro

Question 14

how to use empirical formula to determine molecular formula:

Answer 14

1) find the Mr of the empirical formula by using the Ar values of the compound
2) divide the Mr of the empirical formula by the Mr of the actual compound
3) multiply everything in the empirical formula by the result from step 2

Question 15

definition of empirical formula:

Answer 15

simplest ratio of atoms

Question 16

ammonium ion

Answer 16

NH₄⁺

Question 17

carbonate ion

Answer 17

CO₃⁻²

Question 18

nitrate ion

Answer 18

NO₃⁻

Question 19

hydroxide ion

Answer 19

OH⁻

Question 20

sulfate ion

Answer 20

SO₄⁻²