Atomic StructureIB MYP Chemistry: Topic test

20 questions, 54 marks

IB MYP Chemistry

Atomic Structure topic test

Total 54 marks

Name

Class

Date

1
Phosphorus is used to make matches and fertilisers. It has atomic number 15, and the most common atom of phosphorus has a mass number of 31.
(a)
How many neutrons are in this atom of phosphorus?
[1 mark]
A15
B31
C16
D46
(b)
Which statement about a neutral atom of this phosphorus is correct?
[1 mark]
AIt has 15 protons in the nucleus and 15 electrons outside the nucleus
BIt has 15 protons and 16 neutrons outside the nucleus
CIt has 15 electrons in the nucleus with the protons
DIt has 31 protons in the nucleus and 31 electrons outside it
(c)
Write the electron arrangement of phosphorus and use it to give the group number of phosphorus.
[2 marks]
Total for question 1: 4 marks
2
Boron is used to make heat-resistant glass. It has atomic number 5. Natural boron is a mixture of two isotopes: boron-10, which makes up 20% of the atoms, and boron-11, which makes up 80%.
(a)
How do atoms of boron-10 and boron-11 differ?
[1 mark]
ABoron-11 has one more proton
BBoron-11 has one more electron
CBoron-11 has one more proton and one more electron
DBoron-11 has one more neutron
(b)
Which particles are present in equal numbers in atoms of both isotopes?
[1 mark]
ANeutrons and electrons
BProtons and electrons
CProtons and neutrons
DNeutrons only
(c)
Calculate the relative atomic mass of boron.
[2 marks]
Total for question 2: 4 marks
3
In 1803 John Dalton pictured atoms as tiny solid spheres that cannot be divided. In 1897 J. J. Thomson showed that atoms contain even smaller, negatively charged particles, and he suggested that they were embedded in a ball of positive charge, like raisins in a pudding. In 1913 Niels Bohr proposed a new model with a small central nucleus and electrons moving in fixed shells.
(a)
Explain why Thomson's discovery meant that Dalton's model had to be changed.
[3 marks]
(b)
Describe two differences between Thomson's model and Bohr's model of the atom.
[4 marks]
Total for question 3: 7 marks
4
Lithium has atomic number 3 and is used in rechargeable batteries for electric cars. Natural lithium is mostly lithium-7, with a smaller amount of lithium-6. When a battery is used, lithium atoms lose an electron and form lithium ions. A country with large lithium reserves is deciding whether to expand lithium mining. Mining brings jobs and export income, but extracting lithium from salt lakes uses a very large amount of water in a dry region.
(a)
Compare an atom of lithium-7 with the lithium ion formed from it in terms of protons, neutrons and electrons, and explain why the ion has a charge of 1+. Describe also how lithium-6 differs from lithium-7.
[6 marks]
(b)
Evaluate whether the country should expand lithium mining.
[6 marks]
Total for question 4: 12 marks
5
Potassium has atomic number 19 and mass number 39. It is an essential nutrient for plants, and potassium compounds are used in fertilisers. In these compounds potassium is present as K⁺ ions.
(a)
How many protons and electrons are in a K⁺ ion?
[1 mark]
A19 protons and 19 electrons
B19 protons and 18 electrons
C19 protons and 20 electrons
D18 protons and 18 electrons
(b)
What is the electron arrangement of a potassium atom?
[1 mark]
A2,8,9
B2,8,8
C2,8,1
D2,8,8,1
(c)
Explain why potassium atoms form ions with a charge of 1+.
[2 marks]
Total for question 5: 4 marks
6
Copper has atomic number 29 and is mined in Chile for use in electrical wiring. Natural copper has two isotopes: 69% of the atoms are copper-63 and 31% are copper-65.
(a)
Which statement about the 29 electrons in a neutral copper atom is correct?
[1 mark]
AEach has a relative charge of −1 and a very small mass, and is found outside the nucleus
BEach has a relative charge of −1 and a relative mass of 1
CEach has a relative charge of +1 and is found in the nucleus
DEach has no charge and is found in the nucleus
(b)
How many neutrons are in an atom of copper-65?
[1 mark]
A29
B65
C36
D94
(c)
The relative atomic mass of copper is 63.6, which is not a whole number, although each isotope has a whole-number mass number. Explain why.
[2 marks]
Total for question 6: 4 marks
7
Students in Jakarta are given element cards for aluminium (atomic number 13), fluorine (atomic number 9) and chlorine (atomic number 17). They must work out the electron arrangements and use them to place each element in the periodic table.
(a)
Give the electron arrangement of aluminium and use it to state the period and the group of aluminium.
[3 marks]
(b)
Fluorine and chlorine are in the same group. Use their electron arrangements to explain why, and state the charge on the ion that each of them forms.
[4 marks]
Total for question 7: 7 marks
8
Carbon has atomic number 6. Carbon-12 and carbon-14 are two isotopes of carbon. Archaeologists in Oman want to find the age of an ancient wooden boat by measuring the carbon-14 in its timbers. The method gives an age only to within a few decades, and it destroys the small piece of wood that is tested. Some local people think the boat, which is more than a thousand years old, should be left untouched in its museum.
(a)
Compare atoms of carbon-12 and carbon-14 in terms of protons, neutrons and electrons, and explain why the two isotopes have the same chemical properties.
[6 marks]
(b)
Evaluate whether the archaeologists should remove a small piece of wood from the boat to date it.
[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).