C1 - Atomic Structure

Question 1

What is an element made up of

Answer 1

One type of atom

Question 2

All compounds are molecules but…

Answer 2

Not all molecules are compounds.

Question 3

Molecules are made up of what?

Answer 3

more than one atom.

Question 4

What are compounds made up?

Answer 4

more than one different types of atom

Question 5

What is the law of conservation of mass?

Answer 5

Atoms can not be created nor destroyed.

Question 6

Attributes of compounds:

Answer 6

• Fixed composition
• Atoms chemically bonded
• Chemical reactions must be used for separation

Question 7

Attributes of a mixture:

Answer 7

• No fixed composition
• Atoms not chemically bonded
• Physical separation techniques can be used

Question 8

What are the physical methods of separation?

Answer 8

1. (Paper) chromatography
2. Fractional distillation
3. Distillation
4. Crystallisation/evaporation
5. Filtration

Question 9

How does filtration work?

Answer 9

• We begin with an insoluble solid and a liquid. Let’s take a mixture of salt, sand and water. Salt dissolves in water, however the sand does not.
• Pour the mixture into the filter funnel. When you pour the mixture into a filter funnel lined with filter paper, the sand will be caught by the filter paper and the water with salt dissolved will drip through.
• The separation is complete. The liquid (salt solution) and solid (sand) are separated.

Question 10

What is evaporation/ crystallisation?

Answer 10

Evaporation/crystallisation is when you use evaporation to crystallise and obtain a pure sample of the solute in a solution (for example, when making salts).

• Heat the solution in a water bath or over a bunsen burner in an evaporating dish
• Stop heating at the point of crystallisation then allow the rest of evaporation to take place naturally.
• You are then left with pure crystals of whatever solute was in the mixture.

Question 11

straight for pride

Answer 11

YES !

Question 12

What is distillation?

Answer 12

Distillation allows you to collect the solvent, not just the solute.

• Heat solution over a heat source
• The gas of the solvent once evaporated travels through a glass pipe which has cool water on either side to condense it once again, before collecting the liquid in a beaker as shown below.

Question 13

What is fractional distillation?

Answer 13

Fractional distillation allows one to separate a mixture of two miscible liquids by heating the mixture to one component’s boiling point and allowing the mixture to flow through glass beads to separate the two liquids.

• The set up is the same as simple distillation, except for the glass beads in the neck of the round bottomed flask.

Question 14

What is paper chromatography?

Answer 14

Paper chromatography used to separate (liquid) mixtures as well.

• Filter paper, line in pencil 1-2 cm from bottom, dots of diff mixtures on the line.
• see how soluble in the solvent they are and if they separate in the solvent.
• Distance travelled mixture/distance travelled solvent (seen by looking at the solvent front) = rf value (identification of diff substances).

Question 15

History of the atom:

Answer 15

• Greeks (small hard spheres)
• John Dalton (same thing but said unsplittable)
• JJ Thompson (plum pudding model, discovered electrons)
• Earnest Rutherford (alpha particle experiment, discovered protons/the nucleus, nuclear model)
• Niels Bohr (energy levels, Bohr model)
• James Chadwick (discovery neutrons in the nucleus).

Question 16

No. of protons = ?

Answer 16

No. of electrons

Question 17

Different isotopes of the same element have different numbers of neutrons and therefore…

Answer 17

Different mass numbers <3