Elements, Compounds and Mixtures

Question 1

define an atom and give an example of one

Answer 1

An atom is the smallest unit into which matter can be divided without the release of electrically charged particles e.g. hydrogen atom

Question 2

define an element and give an example of one

Answer 2

a substance that is made up of only one type of atom e.g. hydrogen

Question 3

describe the structure of an atom and give a brief description of the subatomic particles

Answer 3

it has a nucleus in the middle which is orbited by the electrons on the electron shells. The nucleus is made up of protons and neutrons and it occupies a tiny space in the middle of the atom.

the sub-atomic particles are proton (positive), neutron (none) and electron (negative)

Question 4

what are the most common elements on the periodic table

Answer 4

1. hydrogen (h)
2. carbon (c)
3. nitrogen (n)
4. oxygen (o)
5. sulfur (s)
6. magnesium (Mg)
7. sodium (Na)
8. chlorine (Cl)
9. calcium (Ca)
10. copper (Cu)
11. iron (Fe)
12. helium (He)

Question 5

define a mixture and give examples

Answer 5

mixtures are when two or more substances are mingled together and they can be easily separated e.g. sulphur and iron

Question 6

distinguish between a solute, solvent and solution

Answer 6

solute = getting dissolved (usually a solid)
solvent = what the solute is getting dissolved in (usually a liquid)
solution = the mixture of a solute and a solvent

Question 7

define a compounds and give examples of common compounds

Answer 7

a compound is when two or more elements combine as a result of a chemical reaction e.g. water

Question 8

what has to occur for a compound to occur

Answer 8

a chemical reaction

Question 9

define a chemical changes and give examples

Answer 9

an irreversible reaction that creates a new substance e.g. cracking an egg

Question 10

list ways you can observe whether a chemical reaction has taken place

Answer 10

• New substances formed
• Effervescence (bubbles)
• Heat/light/sound
• Electricity produced

Question 11

how to write a word equation

Answer 11

reactant+ reactant(+ reactant) -> product + product (+product)

Question 12

what is a reactant & product

Answer 12

reactant = what is being used
product = the final outcome

Question 13

how to name compounds

Answer 13

-ide = 2 element
-ate = 3+ elements and one of them is oxygen

Question 14

how do you do filtration

Answer 14

Pour the mixture through a funnel of filter paper.

The larger solids will not be able to pass through the paper, but the liquid will.

Residue is what is left (solid)

Question 15

how do you do evaporation

Answer 15

Heat up the mixture to obtain only the solids.

The liquid particles change into gas and move up in the air.

Question 16

how do you do distillation

Answer 16

solid + liquid

First, heat up the mixture with a bunsen burner.

The liquid will rise and it will be condensed by the cold water that is entering from the pipe at the bottom and is exiting from the top.

The liquid will go into the beaker at the end.

Question 17

how do you do chromatography

Answer 17

Put a spot of ink on some chromatography paper.

Balance the paper in a shallow beaker of water.

The more soluble colours will rise (the lighter coloured ones) due to capillary action and it will show you what colours each substances each one is made of.

Question 18

how do you do fractional distillation

Answer 18

liquid + liquid

First, heat up the mixture at the lower boiling point of one of the liquids by a bunsen burner.

The liquid will rise and it will be condensed by the cold water that is entering from the pipe at the bottom and is exiting from the top.

The liquid will go into the beaker at the end.

Question 19

what is the test or water

Answer 19

test: add it to anhydrous copper sulphate
result: it will turn blue from white