Topic 1 - Atomic Structure and the Periodic Table

Question 1

What is an atom?

Answer 1

An atom is the smallest part of an element that can exist

Question 2

What is an element?

Answer 2

An element is a substance of only one type of atom

Question 3

How are the elements listed and how many are there?

Answer 3

They are listed in the periodic table and there are approximately 100

Question 4

Elements can be classified into two groups based on their properties, what are they?

Answer 4

Metals and non-metals

Question 5

Elements may combine through chemical reaction to for new products’, what are these substances called?

Answer 5

Compounds

Question 6

What is a compound?

Answer 6

Two or more elements combined chemically in fixed proportions which can be represented in formulae

Question 7

Do compounds have the same properties as their constituent elements?

Answer 7

No, they have different properties

Question 8

What is a mixture? does it have the same chemical properties as its constituent materials?

Answer 8

A mixture consists of two or more elements or compounds not chemically combined together, it does have the same chemical properties

Question 9

What are the 5 methods through which mixtures can be separated? do theses involve chemical reactions?

Answer 9

• filtration
• crystallisation
• simple distillation
• fractional distillation
• chromatography
• they do not involve chemical reactions

Question 10

Describe and explain simple distillation

Answer 10

Simple distillation is used to separate liquid from a solution - the liquid boils off and condenses in the condenser. the thermometer will read the boiling point of the pure liquid.

Question 11

Describe and explain crystallisation/evaporation

Answer 11

• Evaporation is a technique for separation of a solid dissolved in a solvent from a solvent.
• The solution is heated until all the solvent evaporates, the solids stay in the vessel
• Crystallisation is similar, but we only remove some of the solvent by evaporation to for a saturated solution (the one where no more solids can be dissolved).
• Then, we cool down the solution. as we do it, the solid start to crystallise, as it becomes less soluble at the lowest temperatures.
• The crystals can be collected and separated from the solvent via filtration.

Question 12

Describe and explain fractional distillation

Answer 12

• Fractional distillation is a technique for separation of a mixture of liquids. it works when liquids have different boiling points.
• The apparatus is similar to the one of simple distillation apparatus, with the additional fractioning column placed on top of the heated flask.
• The fractioning column contains glass beads. it helps to separate the compounds.
• The column is hot at the bottom and cool at the top
• The liquids will condense at different heights of the column

Question 13

Describe and explain filtration

Answer 13

• Filtration is used to separate an insoluble solid is suspended in a liquid.
• the insoluble solid (called residue) gets caught in the filter paper, because the particles are too big to fit through the holes in the paper.
• Apparatus: filter paper + funnel

Question 14

Describe and explain chromatography

Answer 14

• Chromatography is used to separate aa mixture of substances dissolved in a solvent
• In paper chromatography, we place a piece of paper with a spot containing a mixture in a beaker with some solvent.
• The bottom of the paper has to be in contact with the solvent
• The solvent level will slowly start to rise, separating the spot (mixture) into few spots (components).

Question 15

What is a separating funnel?

Answer 15

• A separatory funnel is an apparatus for separating immiscible liquids.
• Two immiscible liquids of different densities will form two distinct layers in the separatory funnel
• We can run off the bottom layer (the liquid with greater density) to a separate vessel.