elements, compounds and mixtures

Question 1

what are elements

Answer 1

• elements are substances that cant be split into anything simpler by chemical means.
• an element contains only one type of atom.
• in models or diagrams they are shown as atoms of a single colour or size
• all pure substances are elements e.g pure metals such as magnesium
• 118 elements and all are shown on periodic table

Question 2

what are compounds

Answer 2

• compounds are formed when two or more elements chemically join (combine)
• compounds are shown as two or more chemically joined elements, all clusters of compounds are the same shape

Question 3

what are mixtures

Answer 3

• in a mixture, the various substances are mixed together and no chemical reaction occurs.
• mixtures can be made from elements and/or compounds.
• the various components can be in ant proportion unlike the compounds e.g putting sugar into tea, you can put as much sugar as you want and it will be a mixture (until it becomes saturated)

Question 4

is sea water an element, mixture or compound

Answer 4

mixture, because the salt in sea water is mixed with the water making it an impurity

Question 5

is magnesium oxide an element, mixture or compound

Answer 5

compound, because the two elements have been chemically joined

Question 6

is hydrogen an element, mixture or compound

Answer 6

element, because it is not joined to anything and it is on the periodic table

Question 7

is mud an element, mixture or compound

Answer 7

mixture, because it is mixed with the different things in the ground, with no chemical reaction

Question 8

is copper sulphate (II) an element, mixture or compound

Answer 8

compound, because it has had a chemical reaction to join copper and the sulfur together

Question 9

is honey an element, mixture or compound

Answer 9

mixture, because honey is not an element, it has had no chemical reaction for it to be formed, and it is a mixture of fructose and glucose and other things

Question 10

is blood an element, mixture or compound

Answer 10

mixture, because blood is not an element, it has had no chemical reaction for it to be formed and it is a mixture of red blood cells, white blood cells and platelets

Question 11

is potassium iodide solution an element, mixture or compound

Answer 11

compound, because potassium is an element and it is chemically joined to this iodide to make a solution

Question 12

how do we find out if a solid is pure

Answer 12

a pure substance will have a set melting point, meaning that if you do three tests exactly the same, you will get the same answer over and over again

Question 13

what is the smallest part of an element

Answer 13

the atom

Question 14

is aluminium an element, mixture or compound

Answer 14

element, because it is on the periodic table and it is not joined to anything

Question 15

is carbon dioxide an element, mixture or compound

Answer 15

compound, because it is two elements on the periodic table, chemically joined.

Question 16

is sulfur an element, mixture or compound

Answer 16

element, because it is on the periodic table and it is not joined to anything

Question 17

is copper an element, mixture or compound

Answer 17

element, because it is on the periodic table and it is not joined to anything

Question 18

is water an element, mixture or compound

Answer 18

mixture, because blood is not an element and it has had no chemical reaction for it to be formed