Atomic Structure- Elements, Compounds & Mixtures

Question 1

An element is a substance which contains only one ____ of atom.

Answer 1

An element is a substance which contains only one TYPE of atom.

Question 2

A ________ is a substance which contains two or more types of elements ______ together.

Answer 2

A compound is a substance which contains two or more types of elements bonded together.

Question 3

Mixtures contain _________ elements or compounds that can be __________ as they are
not __________ ______ together.

Answer 3

Mixtures contain different elements or compounds that can be separated as they are
not chemically bonded together.

Question 4

In chemical reactions the starting materials are called _________ and new ________ are made.

Answer 4

In chemical reactions the starting materials are called reactants and new products are made.

Question 5

What are the four different states and their symbols?

Answer 5

(s) = solid
(l) = liquid
(g) = gas
(aq) = aqueous (dissolved in solution)

Question 6

You separate an insoluble solid from a solution by _________ it out. The solid can then be
washed and dried to remove any ___________.

Answer 6

You separate an insoluble solid from a solution by filtering it out. The solid can then be
washed and dried to remove any impurities.

Question 7

To separate a _______ salt from a solution you evaporate the water to produce _________ of salt.

Answer 7

To separate a soluble salt from a solution you evaporate the water to produce crystals of salt.

Question 8

To separate and collect a liquid from a mixture you use _____________. You can use distillation to separate a _______ of liquids.

Answer 8

To separate and collect a liquid from a mixture you use distillation. You can use distillation to separate a mixture of liquids.

Question 9

what are some physical separating techniques that would be used to separate a mixture

Answer 9

filtration, distillation, crystallization and chromatography

Question 10

what is a molecule

Answer 10

a substance that has any elements chemically combined, even if they are the same element

Question 11

Each element on the periodic table has a symbol. what dope this symbol always start with

Answer 11

a capital letter

Question 12

what does a chemical formula tell us

Answer 12

the elements in a molecule and the numbers of atoms of each element

Question 13

true or false?
the numbers of atoms of each element is fixed

Answer 13

true
we can’t change the numbers, because if we did we would end up with a different compound

Question 14

what happens if you have brackets within a chemical formula

Answer 14

the number on the outside of the bracket multiplies everything within the bracket

Question 15

what do state symbols tell us

Answer 15

the physical state of a chemical e.g. solid, liquid, gas or dissolved in water

Question 16

what equipment is used during filtration

Answer 16

filter funnel, filter paper, conical flask

Question 17

how does the water pass through the filter paper

Answer 17

through tiny holes called pores

Question 18

once the liquid passes through the filter paper what is it called

Answer 18

the filtrate

Question 19

how can you make crystallisation happen quickly

Answer 19

by gently heating our solution to evaporate the water quicker then leaving it to evaporate

Question 20

why is it sometimes better to leave the solution to evaporate by itself

Answer 20

certain chemicals will break down if you heat them

Question 21

what are the two stages involved in simple distillation

Answer 21

1. evaporate the liquid by heating it which turns it into a vapour
2. next you condense the vapor back into a liquid by cooling

Question 22

in simple distillation where do you place the liquid

Answer 22

into the flask

Question 23

what is the flask connected to

Answer 23

a continuous glass tube

Question 24

what surrounds the glass tube

Answer 24

a condenser

Question 25

how does a condenser work

Answer 25

cold water from the tap continuously runs through the condenser to keep the internal glass tube cold

Question 26

expelling how simple distillation works

Answer 26

1. heat the solution by using a bunsen Bruner to turn the liquid into a vapor
2. the vapor rises up the glass tube
3. the thermometer reading then increases
4. the vapor passes into the condenser and is condensed back into a liquid
5. we then collect the liquid into a beaker
6. we are then left with crystals of our solid in the flask and liquid in the beaker

Question 27

how long do you heat the liquid

Answer 27

until it boils

Question 28

how is fractional distillation different from simple distillation

Answer 28

we separate a mixture of different liquids

Question 29

factional distillation only works if the liquids have _________ _______ points.

Answer 29

factional distillation only works if the liquids have different boiling points

Question 30

the equipment for simple distillation is the same as distillation apart from one thing. what is difference

Answer 30

the flask that contains the mixture is attached to a long column containing hundreds of glass beads - a fractionating column

Question 31

explain how fractional distillation works

Answer 31

1. gently heat the mixture to allow both our liquids to start to evaporate - the one with the lower boiling point will evaporate quicker
2. the vapors reach the fractionating column and condense back into a liquid into the conical flask
3. the liquids continue to evaporate and condense which increases the amount of the lower boiling point chemical in the fractionating column.
4. the warm vapors pass up the column and reach the thermometer
5. the vapors then enter the condensor which cools them down and turns them back into the liquid - this liquid is still a mixture of two chemicals
6. once the thermometer stops rising it will have reached the lowest boiling point meaning now we mainly only have 1 chemical
7. as this chemical condense we collect it in a new beaker
8. the liquid will continue evaporating and condensing and once the thermometer is a new constant temperature the other liquid is ready to be collected

Question 32

what is paper chromatography

Answer 32

a physical separation method which allows us to separate different substances based on their solubilities

Question 33

explain how you would carry out paper chromatography when looking at what is in different colored pens

Answer 33

1. take a piece of chromatography paper
2. draw a line near the bottom in pencil
3. put a dot of your first color on the pencil line, and next to it put your second color - you can do this for several colors as long as there is room on the paper
4. place the bottom of your paper into a solvent
5. The solvent makes its way up the paper and dissolves the ink in the two colored dots - meaning the ink is carried up the paper

Question 34

what is the paper called and why

Answer 34

the stationary phase - because it doesnt move

Question 35

what is the solvent called and why

Answer 35

the mobile phase - because it moves

Question 36

how can you tell if a color is pure

Answer 36

if there is only 1 spot

Question 37

how can you tell if a color is a mixture of colors

Answer 37

the single dot will separate into two or multiple dots

Question 38

why does paper chromatography work

Answer 38

because different substances have different solubilities

Question 39

true or false?
a less soluble substance travels further up the paper

Answer 39

false
a more soluble substance travels further up the paper

Question 40

why is the starting line drawn in pencil

Answer 40

do that the solvent doesnt carry the pen ink up with it