The atom, symbols, relative atomic mass, electronic charge and isotopes

Question 1

Define an element

Answer 1

A substance made up of only one type of atom

Question 2

Define a compound

Answer 2

A substance made up of atoms from two or more different elements which have been chemically bonded together

Question 3

Define a mixture

Answer 3

A mixture is made up of two or more elements that are not chemically bonded together
(so the poperties of the substanes in the mixture remain unchanged)

Question 4

Name some physical processes by which mixtures can be separated

Answer 4

Filtration

Crystalisation

Simple or Fractional Distillation

Chromatography

*simple and fractional distillation are two different types

Question 5

What is a solvent?

Answer 5

A liquid in which a substance (solute) is dissolved

think: solvent= the liquid where the solute dissolves

Question 6

What is a solute?

Answer 6

A substance that will be dissolved into a liquid

Question 7

What is a solution?

Answer 7

The result of when a soluble solute is dissolved in a solvent.

Question 8

What is the solute called when it does not dissolve into the solvent?

Answer 8

Insoluble solute

Question 9

What is the solute called when it does dissolve into the solvent

Answer 9

Soluble solute

Question 10

What is an insoluble solute with a solvent called?

Answer 10

A mixture

Question 11

What is a soluble solute with a solvent called?

Answer 11

A solution

Question 12

What does filtration do?

Answer 12

Separates insoluble solutes from a solvent

Question 13

Describe the process of filtration

Answer 13

1. Take a funell and place some filter paper inside and place this ontop of a beaker
2. Pour the mixture through the funnel and filter paper
3. The solvent should filter through into the beaker, the insoluble solvent will be left behind on the filter paper as residue

Question 14

What does Crystalisation do?

Answer 14

Separates soluble solutes from a solution

Question 15

Describe the process of Crystalisation

Answer 15

1. Pour the solution into an evaporation dish
2. Prepare a water bath and place the evaporating dish in the bath so that the solution can be heated gently
3. Now some of the solvent willstart to evaporate and we will start to see crystals forming
4. Stop heating the solution and store the dish in a cooler place. More crystalswill start to form because solids are less soluble in colder temperatures
5. Now filter out these crystals using filter paper and a funnel, then dry out the crystals by leaving them somewhere warm

Question 16

What is simple distillation?

Answer 16

Using the specific boiling points to separate a solvent from a solution

Question 17

Describe the process of simple distillation

Answer 17

1. Using a bunsen burner heat up the solution in the flask
2. This will lead the desired solvent to evaporate
3. As it rises to the top of the flask, the pressure will force it down the condenser
4. The gas will cool and condense back into a liquid
5. This liquid will run down the pipe and be collected in a beaker, after continuous heating, all thatwill be left in the flask is the solute.

Question 18

What is fractional distillation?

Answer 18

Using specific boiling points to separate a mixture of liquids

Question 19

What is paper chromatography

Answer 19

A technique used to separate different substances in a mixture
-paper chromatography separates different dyes in an ink

Question 20

Describe the process of paper chromatography

Answer 20

1. Take a piece of chromatography paper (the stationary phase) and use a pencil to draw the baseline at the bottom of the sheet
2. Add your sample of ink to the pencil line
3. Pour a shallow amount of solvent (e.g water or ethanol) into a beaker
4. Place the filter paper into the beaker, making sure that you don’t submerge the** pencil line** and the spot of ink
5. Place a** lid** ontop of the beaker to stop the solvent from evaporating
6. The** solvent ** is the mobile phase. It will ** seep** up the paper, and the different dyes within the ink will dissolve in the solvent and move up with it.
7. The dye that is more soluble will be more attracted to the mobile phase (the solvent) and travel further up the paper than a substance that is less soluble and more attracted to the stationary phase (the paper). They will end up separating out
8. Take the paper out of the beaker and leave it to dry. This forms a chromatogram

Question 21

What is the mobile phase in chromatography?

Answer 21

The solvent (e.g water or ethanol) in which the molecules can move in

hence it is mobile

Question 22

What is the stationary phase in chromatography?

Answer 22

The substance or material that the molecules can’t move in
(e.g. a solid like paper or a really thick liquid)

hence it’s the stationary phase

Question 23

Why do we draw the baseline in pencil?

Answer 23

If we drew the line in pen, the pen ink could dissolve in the solvent and move up the paper. Pencil will not do this.

Question 24

What were atoms originally thought to be?

Answer 24

Tiny spheres that could not be divided

Question 25

What did Rutherford's Goild Foil Experiment Consist of?

Answer 25

Rutherford fired **positively charged alpha particles** at a sheet of **gold foil** which was surrounded by a **flourescent detector** which would **flash** when **hit by alpha partciles**

Question 26

What were the **results** of the **Rutherford Gold Foil** Experiment?

Answer 26

Some of the particles bounced back Some of the particles were deflected at large angles Some of the particles went through the foil.

Question 27

What conclusions did Rutherford come up with as a result of the Gold Foil Experiment?

Answer 27

As** some of the particles went through**, he concluded that the **atom consists of mostly empty space** As some of the particles **bounced back**, he concluded that there was a very **dense centre** where the mass of an atom was concentrated (the **nucleus**) As some of the particles **deflected at large angles**, he concluded that the nucleus was positively charged, as the **alpha particles** he fired at the sheet were **positively charged** and **like charges repel eachother**.

Question 28

Who created the **plum pudding** model of the atom?

Answer 28

J.J Thompson

Question 29

What is the **plum pudding model**?

Answer 29

The plum pudding model suggested that the atom was a **ball of positive charge** with **negative electrons** **embedded** in it

Question 30

**Name four differences** between the **plum pudding model** and the **nuclear model**

Answer 30

1. The **nuclear model** is **mostly empty space**, where as the **plum pudding model** is **solid** 2. The **positive charge** of the **nuclear model** is **all in** the **nucleus**, in the plum pudding model the **whole atom** is a **ball** of **positive mass** 3. The **mass** of the **nuclear model** is **concentrated** in the **nucleus**, in the **plum puddingmodel**, the mass is **distributed throughout** 4. In the **nuclear model**, the **electrons orbit** the **nucleus**, in the **plum pudding model**, the **electrons** are **embedded**

Question 31

Who discovered the electron shells?

Answer 31

**Niels Bohr** suggested that electrons orbit the nucleus at fixed distances

Question 32

What is the equation for **relative atomic mass**?

Answer 32

sum of (isotope abundance x isotope mass numbers)/100

Question 33

What is the **relative mass** of a **proton**?

Answer 33

1

Question 34

What is the **relative charge** of a **proton**?

Answer 34

+1

Question 35

What is the **relative mass** of a **neutron**?

Answer 35

1

Question 36

What is the **relative charge** of a **neutron**?

Answer 36

0

Question 37

What is the **relative mass** of an **electron**?

Answer 37

**Very small**

Question 38

What is the **relative charge** of an **electron**?

Answer 38

-1

Question 39

In an atom, the number of **electrons** is equal to the number of what?

Answer 39

**Protons**

Question 40

What is the **overall charge** of an **atom**

Answer 40

0

Question 41

Why do atoms have an **overall charge** of 0?

Answer 41

Atoms have an **equal number of protons and electrons**. Protons are **positively charged** and electrons are **negatively charged** so they cancel eachother out.

Question 42

In what **order** were the **subatomic particles discovered**?

Answer 42

1. Electron 2. Nucleus 3. Proton 4. Neutron

Question 43

How did **Niels Bohr adapt** the **nuclear model of the atom**?

Answer 43

He suggested that **electrons orbit** the **nucleus** at **fixed distances**

Question 44

What did **James Chadwick** discover?

Answer 44

Neutrons

Question 45

Why was **Niel Bohr's** discovery of the **electrons orbitting the nucleus at a fixed distance** significant?

Answer 45

This discovery shows how because the **negative electrons orbit** the **nucleus** on **electron shells** this **stops the atoms from collapsing**

Question 46

Why was **gold** used in the gold foil experiment?

Answer 46

Gold **can be flattened out **to a thickness of **one atom thick** so the **particles can easily go through it**

Question 47

Define an **isotope**

Answer 47

An atom with the **same number** or **protons** but a **different number** of **neutrons**

Question 48

Define an **ion**

Answer 48

An atom with the **same number** of **protons** but a **different number** of **electrons**

Question 49

What is the **defenition** of a **molecule**?

Answer 49

A particle made up of **two or more** atoms that have been **chemically bonded together**

Question 50

Why was **Mendeleev's Periodic Table widely accepted**?

Answer 50

1. He **left gaps for unknown elements**, **when they were discovered**, these **elements fit the gaps** 2. Mendeleev **predicted** the **properties** of **undiscovered elements correctly**

Question 51

What is the **definition** of an **element**?

Answer 51

A substance that is made up of only **one** type of atom

Question 52

Who discovered the **electron**?

Answer 52

**J.J Thompson**

Question 53

**Why** did **Mendeleev reverse** the **order** of some **pairs** of **elements**? | [**1 mark**]

Answer 53

So that the **properties** of the **metal matched** the **rest** of the **group**