GCSE CHEM (c1)

Name the models of the atom shown in above figure.(F)

A=plum pudding

B=Bohr

Compare model A with the model of the atom used today.

Use the figure above. (F)

(Plum pudding)

Similarities

• both contain electrons

• both are neutral overall

Differences

• model A has no nucleus

or

the model used today has a nucleus

• model A has no protons

or

the model used today has protons

• model A has no neutrons

or

the model used today has neutrons

• model A has positive charge spread throughout the atom

or

model A is a ball of positive charge

• the model used today has the positive charge in the centre

• model A the electrons are distributed randomly

• the model used today has electrons in shells / energy levels

• the mass was spread throughout model A

• the mass is concentrated at the centre of the model used today

• model A does not have empty space

Modem used today is mostly empty space

Chadwick’s experiments showed the existence of neutrons in an atom.

This led to an understanding of isotopes.

Define the term ‘isotopes’.

Refer to subatomic particles in your answer.(F)

atoms with the same number of protons

allow atoms of the same element

allow atoms with the same

atomic number

1

with different numbers of neutrons

Which particles have the same relative mass?(F)

a neutron and a proton

The formula of a compound is N2O

How many of each type of atom are in one molecule of N2O?(F)

nitrogen) 2 / two

(oxygen) 1 / one

An atom of element Z contains:

• 3 electrons

• 4 neutrons

• 3 protons.

(d) Give the name of element Z.

Use the periodic table.(F)

lithium

Describe the plum pudding model of the atom.(F)

a ball of positive charge

do not accept references to protons, nuclei,

neutrons

1

with (negative) electrons embedded

An atom of element Z contains:

• 3 electrons

• 4 neutrons

• 3 protons.

(d) Give the name of element Z.

Use the periodic table.(F)

lithium

Very few atoms of the element tennessine (Ts) have ever been identified.

The atomic number of tennessine is 117

(c) Predict the number of outer shell electrons in an atom of tennessine.

Give one reason for your answer.

Use the periodic table.

Number of outer shell electrons _______

Reason (F)

(number of outer shell electrons) 7

1

(reason) (tennessine is in) Group 7

1

Tennessine was first identified by a small group of scientists in 2010.

Suggest one reason why tennessine was not accepted as a new element by other

scientists until 2015.(F)

(time needed for) peer review

Calculate the relative atomic mass (Ar) of element R.

Give your answer to 1 decimal place.(F)

An atom of element Y has:

• an atomic number of 9

• a mass number of 19.

Give the number of electrons and the number of neutrons in this atom.(F)

number of electrons) 9

1

(number of neutrons) 10

Calculate the relative atomic mass (Ar) of element Z.(F)

Suggest the identity of element Z.(F)

potassium / K

Isotopes of the same element have different mass numbers because the isotopes

have different numbers of _______________.(F)

Neutrons

This question is about the periodic table.

Sodium and potassium are in Group 1 of the periodic table.

(a) Give one similarity and one difference between the electronic structures of sodium

and potassium.(F)

Similarity __________________________________________________________

___________________________________________________________________

Difference _________________________________________________________

___________________________________________________________________

(similarity)

both have one outer (shell)

electron

allow energy level for shell

allow same number of outer (shell) electrons

1

(difference)

sodium has 3 shells but

potassium has 4 shells

Group 1 elements react with water.

(b) Give two observations made when potassium reacts with water.(F)

any two from:

• effervescence / bubbles / fizzing

ignore gas produced

• (potassium) floats

• (potassium) moves around

• (potassium) becomes smaller

• (potassium) melts

allow (potassium) forms a ball

ignore colour of flame

• flame

• explosion

Potassium hydroxide solution is produced when potassium reacts with water.

What is the colour of universal indicator when added to potassium hydroxide

solution?

Give one reason for your answer.(F)

Colour of universal indicator _________________________________________

Reason __________________________________________________________

blue / violet / purple

(the solution is) alkaline

Estimate the density (X) of krypton.

Use the figure and table above.(F)

3.4

The elements in Group 7 are called the halogens.

A more reactive halogen can displace a less reactive halogen from a solution of its

salt.

Which combination of solutions will produce a reaction when mixed?(F)

chlorine and potassium bromide

Which of the following describes the trends going down Group 7?(F)

relative molecular mass increases and boiling point increases

The scientist left gaps in the periodic table in the figure above.

Each gap is represented by a question mark (?).

Give one reason why the scientist left gaps in this periodic table.(F)

for elements that had not been discovered (at that time)

allow for missing elements

or

so that elements with similar properties are grouped together

The modern periodic table is different from the periodic table in above figure.

One extra group of elements has been added.

What is the name of the extra group of elements in the modern periodic table?(F)

noble gases

Why do the elements in Group 1 of the modern periodic table have similar chemical

properties?(F)

the elements all have one electron in the outer shell

Predict value X.(F)

63 (°C)

allow a value in the range 49 to 88 (°C)

Give one observation you would see when a small piece of potassium is added to

water.(F)

any one from:

• floats

• moves (on the surface)

• melts

allow forms a ball

• fizzes / bubbles

• flame

F

This question is about elements in the periodic table.

(a) Argon has the atomic number 18

Explain why argon does not form compounds.

Answer in terms of electrons.(H)

(a) (atoms of) argon have a stable arrangement of electrons

allow (atoms of) argon have a full outer shell (of

electrons)

1

(so) argon (atoms) do not share / transfer electrons

Phosphorus (P) is the element below nitrogen in the periodic table.

Predict the formula of the compound formed between phosphorus and hydrogen.

Formula = _(H)

PH3

Tellurium is the element with atomic number 52

Predict whether tellurium reacts with metals.

Explain your answer.

Answer in terms of the position of tellurium in the periodic table.(H)

yes, because tellurium is towards the right of the periodic table

allow yes, because tellurium is in Group 6

1

(so) tellurium is a non-metal(1)

Or

yes, because tellurium is in the same group as oxygen / sulfur (1)

(and) oxygen / sulfur will react with metals (1)

Or

cannot predict as tellurium is towards the bottom and to the right of

the periodic table (1)

(so) don't know whether tellurium is a metal or non-metal (1)

Barium (Ba) is an element in Group 2 of the periodic table.

Barium reacts with hydrochloric acid.

(d) Suggest two observations that could be made when barium reacts with hydrochloric

acid.(H)

any two from:

• effervescence / fizzing / bubbles

ignore produces a gas

• barium disappears

allow barium gets smaller

• forms a colourless solution

• temperature increases

Write a balanced symbol equation for the reaction between barium and hydrochloric

acid.(H)

Ba + 2 HCl BaCl2 + H2

This question is about groups in the periodic table.

The elements in Group 1 become more reactive going down the group.

Rubidium is below potassium in Group 1.

(a) Rubidium and potassium are added to water.

Predict one observation you would see that shows that rubidium is more reactive

than potassium. (H)

any one from:

• more vigorous bubbling (for rubidium)

• bigger / brighter flame (for rubidium)

allow converse statements for potassium

allow (rubidium) catches fire more quickly

allow (rubidium) moves around more quickly

allow (rubidium) explodes

allow (rubidium) disappears more quickly

allow (rubidium) melts more quickly

Explain why rubidium is more reactive than potassium.(H)

(rubidium’s) outer shell / electron is further from the nucleus

allow the (rubidium) atom is larger

allow (rubidium) has more shells

1

(so) there is less (electrostatic) attraction between the nucleus and the

outer electron (in rubidium)

allow (so) there is more shielding between the outer electron

and the nucleus (in rubidium)

1

(so) the outer electron (in rubidium) is more easily lost

allow (so) less energy is needed to remove the (outer)

electron (in rubidium)

allow energy level for shell throughout

allow converse argument in terms of potassium

Complete the equation for the reaction of rubidium with water.

You should balance the equation.

Rb + H2O + (H) (3)

2 Rb + 2 H2O 2 RbOH + H2

The noble gases are in Group 0.

(d) Which is a correct statement about the noble gases?(H)

the noble gases have boiling points that increase going down the group

H

F

SECTIONS A B AND C

Which two of the following are typical properties of a transition metal? (chemistry

only)

can be bent and shaped

good conductor of electricity

F

1.B

2.A

This question is about metals.

(a) Platinum is used to make jewellery.

Suggest one reason why platinum is used to make jewellery. F

any one from:

• unreactive

allow does not react with air / water / skin

allow does not tarnish

• appearance

allow aesthetic reasons

• easily shaped

allow malleable

allow easily moulded

ignore references to cost

ignore references to hardness / strength

ignore references to melting / boiling point

Give two observations that could be seen when sodium is added to water. F

any two from:

• bubbles

• moves

• floats

• melts

allow forms a ball

• disappears

allow catches fire

(c) Copper is a transition element.

Sodium is a Group 1 element.

What are two differences between copper and sodium? (chemistry only) F

copper is harder

1

copper is less reactive

The metals aluminium and copper can be used to make pans for cooking.

The table below shows information about the two metals.

The higher the value for thermal conductivity, the better the metal conducts thermal

energy.

copper is the better conductor

• so heats food more quickly

• copper has the higher density

• so the pan is heavier

• copper costs more per kilogram

• so the pan is more expensive to buy

• simple judgement

Give two differences between the physical properties of the elements in Group 1

and those of the transition elements. (chemistry only) F

(Group 1 elements)

• have lower melting / boiling points

• have lower densities

• are less strong

• are softer

allow (Group 1 elements are) more malleable / ductile

allow (Group 1 elements) are not useful as catalysts

ignore transition elements form coloured compounds

ignore transition elements form ions with different charges

ignore references to chemical properties

allow converse statements for transition elements

Aluminium is a metal.

Describe how metals conduct electricity.

Answer in terms of electrons.

delocalised electrons

allow free electrons

1

(the electrons) carry (electrical) charge

ignore current / electricity for charge

1

(the electrons move) through the metal / aluminium / structure

Name the type of bonding in compounds formed between metals and non-metals.

ionic

Magnesium oxide is a compound formed from the metal magnesium and the

non-metal oxygen.

Describe what happens when a magnesium atom reacts with an oxygen atom.

You should refer to electrons in your answer. F

magnesium (atom) loses electrons

1

oxygen (atom) gains electrons

1

two electrons (are transferred)

1

magnesium ions and oxide ions are formed

This question is about elements, compounds and mixtures.

(a) Substance A contains only one type of atom.

Substance A does not conduct electricity.

Which type of substance is A?