Topic 4 Atomic Structure F, Slides of Physics

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Topic 4 Atomic Structure F

Name: ________________________

Class: ________________________

Date: ________________________

Time: 40 minutes

Marks: 39 marks

Comments:

Q1. The diagram represents an atom of beryllium. The three types of particle that make up the atom have been labelled.

(a) Use the labels from the diagram to complete the following statements.

Each label should be used once.

The particle with a positive charge is ..........................................................................

The particle with the smallest mass is ........................................................................

The particle with no charge is ..................................................................................... (2)

(b) What is the mass number of a beryllium atom?

Draw a ring around your answer.

Give a reason for your answer.

........................................................................................................................

........................................................................................................................ (2) (Total 4 marks)

Q2. (a) The diagram represents a helium atom.

(c) The graph shows how the count rate from a source of alpha radiation changes with time.

What is the count rate after 4 hours?

............................................. counts per second (1) (Total 4 marks)

Q3. The pie chart shows the average proportions of natural background radiation from various sources in the UK.

(a) (i) Complete the following sentence.

On average, .......................................................... of the natural background

radiation in the UK comes from radon gas. (1)

(ii) Radon gas is found inside homes.

The table shows the results from measuring the level of radon gas inside four homes in one area of the UK.

Home Level of radon gas in Bq per m^3 of air

1 25

2 75

3 210

4 46

Mean 89

One of the homes has a much higher level of radon gas than the other three homes.

What should be done to give a more reliable mean for the homes in this area of the UK?

Put a tick ( ) in the box next to your answer.

ignore the data for home number 3

measure the radon gas level in more homes in this area

include data for homes from different areas of the UK

(1)

(b) Each atom of radon has 86 protons and 136 neutrons.

(i) How many electrons does each atom of radon have?

Draw a ring around your answer.

Q5. Alpha, beta and gamma are types of nuclear radiation.

(a) Draw one line from each type of radiation to what the radiation consists of.

Type of radiation

What radiation consists of

Electron from the nucleus

Alpha

Two protons and two neutrons

Beta

Electromagnetic radiation

Gamma

Neutron from the nucleus

(3)

(b) A teacher demonstrates the penetration of alpha, beta and gamma radiation through different materials.

The demonstration is shown in the figure below.

Complete the figure above by writing the name of the correct radiation in each box. (2)

(c) Give two safety precautions the teacher should have taken in the demonstration.

1 ..........................................................................................................................

(2)

(d) The table below shows how the count rate from a radioactive source changes with time.

Time in seconds^0 40 80 120

Count rate

in counts / second

Use the table to calculate the count rate after 200 seconds.

.............................................................................................................................

............................................................................................................................. (2)

(e) The half-life of the radioactive source used was very short.

Give one reason why this radioactive source would be much less hazardous after 800 seconds.

.............................................................................................................................

............................................................................................................................. (1) (Total 10 marks)

Q6. The equation below shows the process by which two atomic nuclei join to form a different nucleus.

(a) Where does the process shown by the equation above happen naturally?

Tick ( ) one box.

(2)

(ii) State one way in which the process of nuclear fusion differs from the process of nuclear fission.

................................................................................................................

................................................................................................................ (1)

(b) The following nuclear equation represents the fission of uranium-235 (U-235).

Chemical symbols:

Ba - barium

Kr - krypton

(i) Use the information in the equation to describe the process of nuclear fission.

................................................................................................................

................................................................................................................

................................................................................................................

................................................................................................................

................................................................................................................

................................................................................................................

................................................................................................................

................................................................................................................ (4)

(ii) An isotope of barium is Ba-139. Ba-139 decays by beta decay to lanthanum-139 (La-139).

Complete the nuclear equation that represents the decay of Ba-139 to La-139.

(3)

(Total 10 marks)

M3. (a) (i) half / 50 % 1

(ii) Measure the radon gas level in more homes in this area 1

(b) (i) 86 1

(ii) 222 1 [4]

M4. four lines correct

allow 1 mark for each correct line if more than 1 line is drawn from a box in List A, mark each line incorrect

[4]

M5. (a) Alpha – two protons and two neutrons 1

Beta – electron from the nucleus 1

Gamma – electromagnetic radiation 1

(b) Gamma

Beta

Alpha allow 1 mark for 1 or 2 correct 2

(c) any two from:

• (radioactive) source not pointed at students
• (radioactive) source outside the box for minimum time necessary
• safety glasses or eye protection or do not look at source
• gloves
• (radioactive) source held away from body
• (radioactive) source held with tongs / forceps accept any other sensible and practical suggestion 2

(d) half-life = 80 s 1

counts / s after 200 s = 71 accept an answer of 70 1

(e) very small amount of radiation emitted

(ii) 56 (Ba) 1

57 (La) if proton number of Ba is incorrect allow 1 mark if that of La is 1 greater 1

accept e for β

scores 3 marks 1 [10]