T1: Week 1 & 2

Question 1

What are the physical properties that can be used to separate particles?

Answer 1

• Particle size
• Melting and Boiling Point
• Density
• Solubility
• Electric Charge

Question 2

What is sieving?

Answer 2

• Separates a mixture of solids
• Involves passing the mixture through a mesh
• Smaller particles pass through the holes in the mesh, leaving larger particles behind
• Used in baking to seperate lumps in powers such as flour or cocoa

Question 3

What is filtration?

Answer 3

• Separates a solid from a liquid or gas
• Used in air filters in vacuum cleaners, industrial chimneys or extraction fans
• Scientists use filter paper

Question 4

What is gravitational filtration?

Answer 4

• Uses the weight of the mixture
• Liquid is the filtrate, solid is the residue

Question 5

What is vacuum filtration?

Answer 5

Using a vacuum flask

Question 6

What are the two methods of separation by boiling point?

Answer 6

Evaporation: Solvent boiled off to recover solid solute
Distillation: Evaporated liquid is recovered

Question 7

What is density?

Answer 7

Density is the measure of the mass per unit of volume of a substance. Denser substances sink, and less dense substances will float.

Question 8

What are the two main methods of separation by density?

Answer 8

Sedimentation: settling, gravitational separation
Decantation: pouring liquid from sediment

Question 9

What are separation funnels and how are they utilised?

Question 10

What is centrifugation?

Question 11

How can pure substances be further categorised?

Answer 11

Ionic compounds: Metal and non metal ion (transferring of electrons from metal to non metal)
Covalent compounds: Non metals (Sharing of electrons between non metals)

Question 12

How is an ionic compound formed?

Answer 12

Cation: Positively charged
- Atom loses the outermost shell electron
- Rule: Metals lose electrons
Anion: Negatively Charged
- Formed when atoms gain electrons
- Rule: Non metals gain electrons

Question 13

What does polyatomic mean?

Answer 13

More than one atom

Question 14

What is valency?

Answer 14

Number that measures the combining power of the element when it forms compounds. When an element forms ionic compounds, the valency of the element is the numerical value of the charge that the ion of the element carries.

Question 15

How do you describe a covalent compound?

Answer 15

Covalent compounds share electrons to obtain a full shell of eight electrons.

Question 16

How do you name a covalent compound?

Answer 16

• Name the element that occurs further left in the periodic table. If the element is in the same group, the element in the lower down on the periodic table is named first. The suffix -ide is added to the end of the second element. The number of atoms of each element is added as a prefix.

Question 17

What are the prefixes for atoms in covalent compounds?

Answer 17

1 - Mono
2 - Di
3- Tri
4 - Tetra
5 - Penta
6 - Hexa
7 - Hepta
8 - Octa
9 - Nona
10 - Deca

Question 18

What is relative atomic mass?

Question 19

How do you calculate relative atomic mass?

Question 20

What is Mass Spectometry?