1a. Atoms, Elements, Compounds and Mixtures

Question 1

Describe the structure of an atom. Use the terms ‘proton’, ‘neutron’, ‘electron’, ‘nucleus’ and ‘shell’ in your answer.

Answer 1

E.g. atoms have a small nucleus surrounded by electrons. The nucleus is in the middle of the atom and contains protons and neutrons. The electrons occupy shells around the nucleus.

Question 2

What is the relative size of the nucleus compared to the atom?

Answer 2

The nucleus is about 1/10,000 the size of the atom.

Question 3

What is the relative charge of…

a) a proton?
b) a neutron?
c) an electron?

Answer 3

a) +1
b) 0
c) -1

Question 4

What is the relative mass of a proton?

Answer 4

1

Question 5

Atoms are uncharged particles. Explain why.

Answer 5

They have the same number of protons as electrons and protons and electrons have opposite charges of the same size, so cancel each other out.

Question 6

What is an element?

Answer 6

An element is a substance containing only one type of atom.

Question 7

a) What does the atomic number tell you about an atom?

b) What does the mass number tell you about an atom?

Answer 7

a) The number of protons in the atom.

b) The total number of neutrons and protons in the atom.

Question 8

How would you find the number of neutrons in an atom from the mass number and the atomic number?

Answer 8

By subtracting the atomic number from the mass number.

Question 9

Is the following statement true or false?

All atoms of an element have the same number of protons.

Answer 9

True

Question 10

What are isotopes?

Answer 10

Isotopes are different forms of the same element, which have the same number of protons but a different number of neutrons.

Question 11

What is relative atomic mass?

Answer 11

An average mass of an element, taking into account the different masses of the isotopes, along with their relative abundances.

Question 12

What are compounds?

Answer 12

Compounds are substances formed from two or more elements, the atoms of which are bonded together in fixed proportions throughout the compound.

Question 13

Do metal atoms form positive ions or negative ions when they form a compound?

Answer 13

Positive ions.

Question 14

What type of bonding holds the atoms in a molecule together?

Answer 14

Covalent bonding.

Question 15

What is a mixture?

Answer 15

A mixture is a substance which consists of two or more elements or compounds which aren’t joined together by chemical bonds.

Question 16

Describe the properties of a mixture compared to the properties of its components.

Answer 16

The properties of a mixture are a mixture of the properties of its components.

Question 17

List three physical methods that can be used to separate mixtures.

Answer 17

Any three from: e.g. chromatography, filtration, crystallisation, simple distillation, fractional distillation.

Question 18

During paper chromatography, why must you make sure the ink spot doesn’t touch the solvent when you place the filter paper into the solvent?

Answer 18

Because the ink might be washed away by the solvent.

Question 19

Why do you place a lid on top of the container whilst carrying out paper chromatography?

Answer 19

To stop the solvent evaporating.

Question 20

What is the pattern of spots produced by paper chromatography known as?

Answer 20

A chromatogram.

Question 21

How could you use paper chromatography to separate more than one ink at a time on a single piece of filter paper?

Answer 21

You could spot all the inks separately at different points along the base line on the same piece of filter paper.

Question 22

Give one technique that can be used to separate an insoluble solid from a liquid.

Answer 22

E.g. filtration

Question 23

List the equipment you could use to carry out evaporation.

Answer 23

E.g. an evaporating dish, a tripod, a Bunsen burner and a gauze mat.

Question 24

What is the final stage in crystallisation?

Answer 24

Drying the crystals.

Question 25

Who described atoms as solid spheres in the early 19th century?

Answer 25

John Dalton

Question 26

Whose experiments provided evidence of the neutron?

Answer 26

James Chadwick

Question 27

What is another name for an electron shell?

Answer 27

An energy level.

Question 28

What is the maximum number of electrons that can go in the first electron shell?

Answer 28

2 electrons.

Question 29

What is the maximum number of electrons that can go in the second electron shell?

Answer 29

8 electrons.

Question 30

What is the maximum number of electrons that can go in the third electron shell?

Answer 30

8 electrons.

Question 31

Which shell fills with electrons first?

Answer 31

The one closest to the nucleus. / The one with the lowest energy level.