deck_16581369 (1)

Question 1

Describe the plum pudding model of the atom.

Answer 1

a ball of positive charge

with (negative) electrons
embedded

Question 2

Atoms contain electrons, neutrons and protons.

Write these three particles in order of their discovery.

Answer 2

(earliest) electrons
protons
(latest) neutrons

Question 3

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

Give one reason for your answer.

Use the periodic table.

Answer 3

(number of outer shell electrons)
7

(reason) (tennessine is in)
Group 7

Question 4

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.

Answer 4

(time needed for) peer review

Question 5

How do the results show that dissolving ammonium nitrate in water is endothermic?

Answer 5

temperature decreased

Question 6

The student recorded the mean lowest temperature of the solution for 8.0 g of
ammonium nitrate as 16.5 ± 0.3 ºC.

Explain why the student included ± 0.3 ºC after the mean lowest temperature.

Answer 6

(0.3 °C) is the uncertainty

(because 0.3 °C) is the range
about the mean value

Question 7

Name two other substances that can each be reacted with a dilute acid to make
zinc chloride.

Do not refer to zinc carbonate in your answer.

Answer 7

any two from:
* zinc
* zinc oxide
* zinc hydroxide

Question 8

Plan a method to make pure, dry crystals of zinc chloride from zinc carbonate and a
dilute acid.

Answer 8

• use zinc carbonate and hydrochloric acid
• add zinc carbonate to the (hydrochloric) acid
• in a beaker
• stir
• continue adding until the zinc carbonate is in excess
• shown by excess solid
• and no more effervescence
• filter (the reaction mixture)
• to remove the excess zinc carbonate
• heat the solution
• using a water bath or electric heater
• to crystallisation point
• leave the solution to crystallise
• pat crystals dry with filter paper

Question 9

The reaction between hydrogen and chlorine is exothermic.

Explain why this reaction releases energy to the surroundings

Answer 9

energy is needed to break
bonds
and
energy is released when bonds
form

(and) the energy released is
greater than the energy needed

Question 10

Methane is a gas at room temperature but poly(ethene) is a solid at room
temperature.

Explain why methane and poly(ethene) exist in different states at room temperature.

Answer 10

(methane)

methane has (much) smaller
molecules

(so) has weaker intermolecular
forces

(so the intermolecular forces)
need less energy to overcome

(so) the boiling / melting point is
lower (and methane is a gas)

OR

(poly(ethene))

poly(ethene) has (much) larger
molecules (1)

(so) has stronger intermolecular
forces (1)

(so the intermolecular forces)
need more energy to break (1)

(so) the melting / boiling point is
higher (and poly(ethene) is a
solid) (1)

Question 11

Ethanoic acid is a weak acid.

What is meant by ‘weak acid’?

Answer in terms of ionisation.

Answer 11

(the acid is only) partially ionised
(in aqueous solution)

Question 12

The concentration of an acid can be measured in mol/dm3.

Which combination of changes increases the concentration of an acid?

Answer 12

the mass of acid dissolved is
doubled and the volume of the
solution is halved

Question 13

Which element has atoms that have the same electronic structure as the chloride ion?

Use the periodic table.

Answer 13

argon / Ar

Question 14

Evaluate the use of aluminium, copper and silver for the types of electrical wires
shown in Figure 6.

Answer 14

• silver is the best electrical conductor
• aluminium is the least dense
• aluminium is the least expensive
• copper is a better conductor than aluminium
  or
  copper is almost as good a conductor as silver
• copper is much less expensive than silver
• overhead power cables need a low density metal
• wiring in homes needs to be affordable
• printed circuit boards only require small amounts of material

judgements
* use aluminium for overhead wires because of aluminium’s
low density and/or lower cost

• use copper for domestic wiring because copper is a very good
  conductor and not too expensive
• use silver only for small uses such as circuit boards due to high
  cost
• copper is a good compromise between electrical conductivity and
  cost

Question 15

Describe how metals conduct electricity.

Answer 15

(metals have) delocalised
electrons

the electrons carry (electrical)
charge

the electrons move through the
structure / metal

Question 16

Electrical wires are usually made of pure metals and not alloys. This is because pure
metals are better electrical conductors.

Suggest why alloys do not conduct electricity as well as pure metals.

Answer in terms of structure and bonding.

Answer 16

in alloys different sized atoms
distort the layers / structure

(so) the movement of
(delocalised) electrons is
restricted

Question 17

Cryolite contains Na+ ions as well as Al3+ ions.

Suggest one reason why sodium is not a product of the electrolysis.

Answer 17

sodium is more reactive than
aluminium

Question 18

Hydrogen was produced at the negative electrode and oxygen was produced at the
positive electrode.

Explain how oxygen was produced from water during the electrolysis of this
aqueous solution.

Answer 18

water (molecules) break down

(to) produce (H+ and) OH− (ions)

(so) OH− (ions) are attracted /
move to the positive electrode

(where) OH− (ions) are
discharged / oxidised to give
oxygen (molecules)

Question 19

The student compared the volumes of the two gases collected.

How can the student change the apparatus in Figure 7 to compare the volumes of the
two gases produced more accurately?

Give one reason for your answer.

Answer 19

(change)
use measuring cylinders
(instead of test tubes)

(reason)
because there is a scale (on the
measuring cylinders)

Question 20

Argon has the atomic number 18

Explain why argon does not form compounds.

Answer in terms of electrons.

Answer 20

(atoms of) argon have a stable
arrangement of electrons
(so) argon (atoms) do not share
/ transfer electrons

Question 21

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

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

Answer 21

PH3

Question 22

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.

Answer 22

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

(so) tellurium is a non-metal

OR

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

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

OR

no, because tellurium is towards
the bottom of the periodic table
(1)

(so) tellurium is a metal (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)

Question 23

Suggest two observations that could be made when barium reacts with
hydrochloric acid.

Answer 23

any two from:
* effervescence / fizzing /
bubbles
* barium disappears
* forms a colourless solution
* temperature increases

Question 24

Which substance in the equation is reduced?

Give one reason for your answer.

Answer in terms of oxygen.

Answer 24

(substance reduced) Fe2O3

(reason)
(Fe2O3) loses oxygen

Question 25

The ionic equation for Reaction 1 is:

A + 2 B+ → 2 B + A2+

Why is this a redox reaction?

Answer 25

A loses electrons and B+ gains
electrons

Question 26

The nitrate ion has the formula NO3–

Which of the four metals could be aluminium?

Explain your answer.

Answer 26

(metal) C

(explanation) aluminium forms
ions with a charge 3+

(so) 3 nitrate ions are needed
for 1 aluminium ion

Question 27

Self-cleaning windows are coated with a layer of nanoparticles of titanium dioxide.

Titanium dioxide:
* helps sunlight break down dirt particles
* attracts water, so dirt is washed away by rain.

Nanoparticles of titanium dioxide are used instead of fine particles of titanium dioxide
for coating self-cleaning windows.

Suggest two reasons why.

Answer 27

(nanoparticles)
any two from:
* have a higher surface area to
volume ratio
* less (material) needed (for the
same effect)
* more light gets through