AtomsIB MYP Sciences: Topic test

20 questions, 54 marks

IB MYP Sciences

Atoms topic test

Total 54 marks

Name

Class

Date

1
Calcium is needed for strong bones and teeth. A calcium atom has atomic number 20 and mass number 40.
(a)
How many neutrons are in this calcium atom?
[1 mark]
A40
B20
C60
D10
(b)
In the body, calcium forms Ca²⁺ ions by losing two electrons. How many protons, neutrons and electrons are in one of these ions?
[1 mark]
A20 protons, 20 neutrons, 20 electrons
B18 protons, 20 neutrons, 18 electrons
C20 protons, 20 neutrons, 22 electrons
D20 protons, 20 neutrons, 18 electrons
(c)
Explain why a calcium atom has no overall charge, but a Ca²⁺ ion is charged.
[2 marks]
Total for question 1: 4 marks
2
Sulfur (atomic number 16) is used to harden the rubber in vehicle tyres, and argon (atomic number 18) is used to fill many light bulbs.
(a)
What is the electron configuration of a sulfur atom?
[1 mark]
A2,8,6
B2,6,8
C2,8,8
D2,8,4
(b)
Why is argon unreactive?
[1 mark]
AIt has only one electron shell.
BIt has a full inner shell but a part-filled outer shell.
CIt has a full outer shell, so its atoms do not need to gain, lose or share electrons.
DIt has more protons than electrons.
(c)
Sulfur is in Period 3, Group 6 (also written Group 16) of the periodic table. Explain how its electron configuration shows this.
[2 marks]
Total for question 2: 4 marks
3
A student in Perth is given data on two particles. Particle P has 12 protons, 12 neutrons and 10 electrons. Particle Q has 17 protons, 20 neutrons and 18 electrons.
(a)
State the atomic number and the mass number of particle Q, and explain whether Q is an atom, a positive ion or a negative ion.
[3 marks]
(b)
(i) Write the electron configuration of particle P and explain why this arrangement is stable. (ii) Another particle has 12 protons, 14 neutrons and 12 electrons. Explain why it is an atom of the same element as P but a different isotope.
[4 marks]
Total for question 3: 7 marks
4
In 1897 the physicist J. J. Thomson studied rays produced in a glass tube from which most of the air had been removed. The rays were attracted towards a positively charged metal plate and repelled by a negatively charged one. They were the same whatever gas was in the tube or metal was used for the electrodes, and the particles in them were far lighter than a hydrogen atom. Until then, most scientists followed John Dalton's idea that atoms were tiny solid spheres that could not be divided.
(a)
Explain how Thomson's evidence showed that Dalton's model was wrong, and how Thomson's model of the atom differed from the nuclear model later proposed by Ernest Rutherford.
[6 marks]
(b)
Scientists from many countries, including Dalton, Thomson, Rutherford and Niels Bohr, changed the model of the atom over time. Discuss why scientific models change, and the implications for how society uses scientific knowledge. Consider both sides and finish with a justified conclusion.
[6 marks]
Total for question 4: 12 marks
5
Chlorine (atomic number 17) is added to drinking water to kill bacteria. Natural chlorine is a mixture of two isotopes, chlorine-35 and chlorine-37.
(a)
How do atoms of chlorine-35 and chlorine-37 differ?
[1 mark]
AThey have different numbers of protons.
BThey have different numbers of electrons.
CThey have different numbers of neutrons.
DThey have different atomic numbers.
(b)
How many neutrons are in an atom of chlorine-37?
[1 mark]
A17
B20
C37
D54
(c)
Chlorine-35 and chlorine-37 react in exactly the same way. Explain why.
[2 marks]
Total for question 5: 4 marks
6
A student in Seoul draws a diagram of a phosphorus atom, atomic number 15, using the shell model in which electrons occupy fixed shells around the nucleus.
(a)
How should the 15 electrons be arranged in the shells of the phosphorus atom?
[1 mark]
A5,8,2
B2,8,8
C2,13
D2,8,5
(b)
Which scientist first suggested that electrons move in fixed shells around the nucleus?
[1 mark]
ABohr
BDalton
CThomson
DRutherford
(c)
Phosphorus atoms can gain three electrons to form P³⁻ ions. Give the electron configuration of a P³⁻ ion and explain why this arrangement is stable.
[2 marks]
Total for question 6: 4 marks
7
Copper wire is used in electrical cables in homes. A copper atom has atomic number 29. Natural copper is a mixture of two isotopes: 69% of its atoms are copper-63 and 31% are copper-65.
(a)
State the number of protons, neutrons and electrons in an atom of copper-65.
[3 marks]
(b)
Calculate the relative atomic mass of copper, using the mass numbers, to one decimal place. Explain why the answer is not a whole number and why it is closer to 63 than to 65.
[4 marks]
Total for question 7: 7 marks
8
A teacher in Accra gives her class a closed wooden box. Fixed to the floor inside the box are one or more hidden circular discs. Students roll small steel balls, one at a time, through a gap in one side of the box and note whether each ball passes straight through or is deflected. The teacher says this models how Ernest Rutherford worked out that an atom has a tiny nucleus without being able to see it. A group tries three boxes, each with one hidden disc, of diameter 2 cm, 4 cm and 6 cm. For each box they roll 50 balls from the same place and count the balls that are deflected. The counts are 6, 13 and 20 balls, in that order. Each box was tested once.
(a)
The group now wants to test whether having more hidden discs in the box increases the number of balls deflected. Plan an investigation. In your answer, state a hypothesis with a scientific reason, identify the variables, and describe a safe method.
[6 marks]
(b)
Process the group's data and evaluate their model and method. Finish with a justified conclusion about whether the investigation supports the idea that the size of a hidden target can be found from how many objects it deflects.
[6 marks]
Total for question 8: 12 marks

End of questions

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).