Topic S1.2 · SL and HL

The nuclear atom: notes and practice questions

10 min read Jump to 20 practice questions

Summary

This topic introduces the nuclear atom model, including its subatomic particles and their arrangement.
Atoms consist of a dense, positively charged nucleus (protons and neutrons) and negatively charged electrons occupying space outside the nucleus.
Use the nuclear symbol $^{A}_{Z}\text{X}$ to deduce the number of protons, neutrons, and electrons in atoms and ions.
Isotopes are atoms of the same element with different numbers of neutrons.
Perform calculations involving non-integer relative atomic masses and isotopic abundance.
Interpret mass spectra to determine the identity and relative abundance of isotopes.

How it is examined

Paper 1A carries the subatomic-particle counting. Weighted-average Ar calculations from isotopic abundance are standard 2-mark Paper 2 parts. At HL the mass spectrum version gives a bar chart of m/z against relative abundance and asks for Ar, still 2 marks. A question asking a student to recall the mass of a proton in kg is a bad question: the booklet supplies it.

Given in the booklet

Actual masses and charges of the proton, neutron and electron. Relative atomic masses to two decimal places in the periodic table. The relative values (proton and neutron 1, electron negligible; charges +1, 0, -1) are recall.

Key ideas

1.2.1 Atoms contain a positively charged, dense nucleus of protons and neutrons (nucleons). Negatively charged electrons occupy the space outside the nucleus. Students use the nuclear symbol (mass number A upper left, atomic number Z lower left, element symbol X) to deduce the number of protons, neutrons and electrons in atoms and ions.
1.2.2 Isotopes are atoms of the same element with different numbers of neutrons. Students perform calculations involving non-integer relative atomic masses and isotopic abundance from given data.

Not assessed

The operational details of the mass spectrometer will not be assessed (HL).

At HL

1.2.3 Mass spectra are used to determine relative atomic masses of elements from their isotopic composition. Students interpret mass spectra in terms of identity and relative abundance of isotopes.

Guiding questions

How do the nuclei of atoms differ?

Linking questions

Structure 1.3 What determines the different chemical properties of atoms?
Structure 3.1 How does the atomic number relate to the position of an element in the periodic table?
Nature of science, Reactivity 3.4 How can isotope tracers provide evidence for a reaction mechanism?
Structure 3.2 (HL) How does the fragmentation pattern of a compound in the mass spectrometer help in the determination of its structure?

Practice questions

29 questions · 15 easy · 11 medium · 3 hard

Showing 20 of 20

Question 1

EasyPaper 2 · calculator1 mark

What is the number of neutrons in an atom of the isotope Cadmium-114 ( $^{114}Cd$ )?

A $48$

B $64$

C $66$

D $114$

Question 2

MediumPaper 1A · calculator1 mark

Which pair of species has the same number of electrons in the outermost principal energy level?

The letters do not represent symbols of elements.

$_{20}^{40}P^{2+}$

$_{16}^{32}Q$

$_{17}^{35}R^{-}$

$_{7}^{14}S$

A. P and Q

B. Q and S

C. P and R

D. R and S

Question 3

HardPaper 2 · calculator24 marks

(a)(i)

Antimony (Sb) and Bismuth (Bi) are elements in group 15 of the periodic table.

(a) Antimony has two stable isotopes. 57.21% of antimony atoms contain 70 neutrons and the remainder contain 72 neutrons.

(i) Deduce the nuclear symbol of the isotope of antimony containing 72 neutrons. Use section 6 of the data booklet.

[1]

(a)(ii)

(ii) Calculate, to two decimal places, the relative atomic mass of antimony.

[2]

(b)(i)

Bismuth(III) nitrate, $Bi(NO_3)_3$ , is a common salt of bismuth.

(b) (i) The compound contains both ionic and covalent bonds. State which particles are joined by covalent bonds and which are joined by ionic bonds.

[2]

(b)(ii)

(ii) Distinguish between covalent and ionic bonding in terms of electron distribution.

[2]

(b)(iii)

(iii) State the enthalpy term that characterizes the strength of the bonding between the ions in an ionic solid.

[1]

(b)(iv)

(iv) Write an equation for the formation of aqueous bismuth(III) nitrate from solid bismuth(III) oxide and nitric acid.

[2]

(b)(v)

(v) Calculate the volume, in $cm^3$ , of $1.50 \text{ mol dm}^{-3}$ nitric acid required to react completely with $5.00 \text{ g}$ of solid bismuth(III) oxide.

[3]

(b)(vi)

(vi) Predict, with a reason, whether bismuth(III) oxide is expected to be primarily acidic, basic or amphoteric.

[1]

(b)(vii)

(vii) Discuss how the relative reactivity of zinc and bismuth could be established using the metals and aqueous solutions of their nitrates.

[2]

(b)(viii)

(viii) Discuss the products formed at the electrodes during the electrolysis of aqueous bismuth(III) nitrate. Use the standard electrode potential $E^\ominus(Bi^{3+}/Bi) = +0.32 \text{ V}$ and section 24 of the data booklet.

[2]

(c)(i)

Bismuth compounds are sometimes used in fireworks to produce special effects.

[1]

(c)(ii)

(ii) Calculate the wavelength, in nm, that corresponds to the first ionization energy of bismuth. Use sections 1, 2 and 8 of the data booklet.

[3]

(c)(iii)

(iii) Explain why the first ionization energy of bismuth is lower than that of polonium (Po), in terms of nuclear charge and electron shielding.

[2]

Question 4

EasyPaper 2 · calculator1 mark

The table below shows the number of subatomic particles for four different species.

Species	Number of protons	Number of neutrons	Number of electrons
P	12	13	10
Q	12	12	12
R	10	10	10
S	11	13	10

Which two species are isotopes of the same element?

A. P and Q

B. P and S

C. Q and R

D. R and S

Question 5

MediumPaper 1A · calculator1 mark

Which property is the same for tetrachloromethane, $CCl_4$ , containing only the $^{35}Cl$ isotope and tetrachloromethane containing only the $^{37}Cl$ isotope?

A. Molar mass

B. Rate of diffusion in the gaseous state

C. Polarity of the carbon-chlorine bond

D. Frequency of the C-Cl bond vibration

Question 6

HardPaper 2 · calculator23 marks

(a)

A sample of chlorine consists of two isotopes, $^{35}Cl$ and $^{37}Cl$ .

(a) Contrast the sub-atomic structure of these two isotopes.

[1]

(b)(i)

(b) (i) The sample of chlorine is analysed in a mass spectrometer, producing a spectrum for the $Cl_2^+$ ion. The spectrum shows three peaks at m/z values of 70, 72 and 74. Explain the origin and relative heights of these three peaks, given that the abundance of $^{35}Cl$ is approximately three times that of $^{37}Cl$ .

[3]

(b)(ii)

(ii) A more precise measurement finds the composition by mass to be: $^{35}Cl$ : 75.76%, $^{37}Cl$ : 24.24%. Calculate the relative atomic mass of chlorine from this sample, giving your answer to two decimal places. (Use isotopic masses of 35.0 and 37.0 for this calculation).

[2]

(c)(i)

Magnesium chloride, $MgCl_2$ , and manganese(II) chloride, $MnCl_2$ , are two ionic compounds.

(c) (i) Deduce the type of bonding in magnesium chloride, $MgCl_2$ , using electronegativity values from section 9 of the data booklet.

[2]

(c)(ii)

(ii) Determine the lattice enthalpy of magnesium chloride, assuming the bonding is purely ionic. Use sections 9, 10 and 12 of the data booklet and the following data:

Enthalpy of formation of magnesium chloride = $-641 \text{ kJ mol}^{-1}$

[3]

(c)(iii)

(iii) Explain, with reference to electron configurations, why the ionic radii of $Mg^{2+}$ , $Mn^{2+}$ and $Cl^-$ are different. Use section 10 of the data booklet.

[3]

(c)(iv)

(iv) Predict, with a reason, which has the stronger ionic bonding, manganese(II) chloride, $MnCl_2$ , or magnesium chloride.

[2]

(d)(i)

Magnesium chloride is white, but manganese(II) chloride is pale pink.

(d) (i) State the condensed electron configuration of a manganese atom.

[1]

(d)(ii)

(ii) State the reason, in terms of electron configuration, why manganese(II) chloride is coloured.

[1]

(d)(iii)

(iii) Manganese(II) chloride absorbs light with a wavelength of approximately 530 nm. Describe why this is consistent with the observed colour of the compound. Use sections 2 and 15 of the data booklet.

[2]

(e)(i)

A copper key is to be electroplated with manganese using an aqueous solution of manganese(II) chloride as the electrolyte.

(e) (i) Deduce the half-equations for the reactions occurring at the anode (made of pure manganese) and the cathode (the copper key).

[2]

(e)(ii)

(ii) Deduce a balanced chemical equation for the reaction of fluorine gas with the aqueous chloride ions in the electrolyte.

[1]

Question 7

EasyPaper 2 · calculator1 mark

The relative atomic mass of bromine is $79.90$ . What is the standard reference for the relative atomic mass scale?

A. The mass of an atom of hydrogen-1

B. The mass of an atom of carbon-12

C. $\frac{1}{12}$ of the mass of an atom of carbon-12

D. $\frac{1}{16}$ of the mass of an atom of oxygen-16

Question 8

MediumPaper 2 · calculator1 mark

Boron has two naturally occurring isotopes, $^{10}B$ and $^{11}B$ . The relative atomic mass of boron is $10.81$ . The isotopic mass of $^{10}B$ is $10.0129$ amu and the isotopic mass of $^{11}B$ is $11.0093$ amu. What are the natural abundances of these two isotopes?

A $^{10}B$ $20.0\%$ and $^{11}B$ $80.0\%$

B $^{10}B$ $50.0\%$ and $^{11}B$ $50.0\%$

C $^{10}B$ $80.0\%$ and $^{11}B$ $20.0\%$

D $^{10}B$ $10.0\%$ and $^{11}B$ $90.0\%$

Question 9

HardPaper 2 · calculator16 marks

(a)(i)

Strontium is an alkaline earth metal in group 2 of the periodic table, used to produce the red colour in fireworks.

(a) In a sample of strontium, 10.0% of the atoms have a mass number of 86 and the remainder have a mass number of 88.

(i) Deduce the nuclear symbol of the isotope of strontium with mass number 86. Use section 6 of the data booklet.

[1]

(a)(ii)

(ii) Calculate, to two decimal places, the relative atomic mass of this sample of strontium.

[2]

(a)(iii)

(iii) Explain why the first ionization energy of strontium is greater than that of rubidium.

[2]

(b)(i)

(b) Strontium nitrate has the formula $Sr(NO_3)_2$ .

(i) The compound contains both ionic and covalent bonds. State which particles are joined by covalent bonds and which are joined by ionic bonds.

[2]

(b)(ii)

(ii) Contrast covalent and ionic bonds in terms of how the valence electrons are involved.

[1]

(b)(iii)

(iii) Write a balanced chemical equation for the formation of strontium nitrate solution from the reaction of solid strontium hydroxide with nitric acid.

[2]

(b)(iv)

(iv) Calculate the volume, in $cm^3$ , of $1.50 \text{ mol dm}^{-3}$ nitric acid required to react completely with $5.00 \text{ g}$ of solid strontium hydroxide.

[3]

(b)(v)

(v) Predict, with a reason, whether strontium oxide is acidic, basic or amphoteric.

[1]

(b)(vi)

(vi) Describe an experiment to establish the relative reactivity of strontium and zinc using the metals and aqueous solutions of their nitrates.

[2]

Question 10

EasyPaper 2 · calculator1 mark

Chlorine has two common isotopes, $^{35}Cl$ and $^{37}Cl$ . Which statements about these isotopes are correct?

I. They have the same number of electrons in a neutral atom.

II. They have different numbers of neutrons.

III. They have different physical properties.

A. I and II only

B. I and III only

C. II and III only

D. I, II and III

Question 11

MediumPaper 2 · calculator1 mark

Copper has two naturally occurring isotopes: $^{63}Cu$ and $^{65}Cu$ . The natural abundance of $^{63}Cu$ is $69.15\%$ and the natural abundance of $^{65}Cu$ is $30.85\%$ . What is the relative atomic mass of copper?

A $63.00$

B $63.62$

C $64.00$

D $65.00$

Question 12

EasyPaper 2 · calculator1 mark

The table shows the composition of four different species.

Species	Nucleon number	Number of protons	Number of electrons
P	$23$	$11$	$10$
Q	$24$	$12$	$12$
R	$19$	$9$	$10$
S	$24$	$11$	$10$

Which species are positive ions?

A. P and Q

B. Q and R

C. R and S

D. P and S

Question 13

MediumPaper 1A · calculator1 mark

Magnesium has three naturally occurring isotopes. A sample of magnesium was analyzed using mass spectrometry, revealing the following isotopic abundances:

$^{24}$ Mg: $78.99\%$

$^{25}$ Mg: $10.00\%$

$^{26}$ Mg: $11.01\%$

What is the relative atomic mass of this sample of magnesium?

A. $24.22$

B. $24.32$

C. $24.42$

D. $25.00$

Question 14

EasyPaper 2 · calculator1 mark

Which of the following isotopes contains the greatest number of neutrons?

A. $^{131}_{54}Xe$

B. $^{137}_{56}Ba$

C. $^{130}_{52}Te$

D. $^{126}_{50}Sn$

Question 15

MediumPaper 1A · calculator1 mark

Bromine is a diatomic molecule. A sample of bromine contains the isotopes $^{79}Br$ and $^{81}Br$ in approximately equal abundance.

Which graph shows the mass spectrum of this sample of bromine?

Mass spectrum showing only peaks in the molecular ion region at m/z = 158, 160, 162 with relative heights in a 1:2:1 ratio.

Mass spectrum showing peaks at m/z = 79 and 81 of equal height, and peaks at m/z = 158, 160, 162 of equal height (1:1:1 ratio).

Mass spectrum showing peaks at m/z = 79 and 81 of equal height, and peaks at m/z = 158, 160, 162 with relative heights in a 1:2:1 ratio. The peak at 160 is the tallest in the molecular ion region.

Mass spectrum showing only peaks in the atomic ion region at m/z = 79 and 81 of equal height.

Question 16

EasyPaper 2 · calculator1 mark

An atom of a certain element has $53$ protons and $78$ neutrons. Which of the following correctly represents the nuclear symbol for this atom?

A $^{131}_{53}I$

B $^{78}_{53}I$

C $^{131}_{78}I$

D $^{53}_{131}I$

Question 17

MediumPaper 1A · calculator1 mark

Which of the following species have the same number of outer electrons? The letters do not represent symbols of elements.

${^{9}_{4}M}$

${^{11}_{5}N^{+}}$

${^{16}_{8}P^{2-}}$

${^{12}_{6}Q}$

A. M and P

B. N and Q

C. M and N

D. P and Q

Question 18

EasyPaper 2 · calculator1 mark

Which of the following species contains more protons than neutrons?

A. $^{11}B$

B. $^{3}He$

C. $^{19}F$

D. $^{23}Na$

Question 19

MediumPaper 1A · calculator1 mark

Which property is the same for a sample of tetrachloromethane, $CCl_4$ , containing only the $^{35}Cl$ isotope and a sample containing only the $^{37}Cl$ isotope?

A. Boiling point

B. Polarity of the C–Cl bond

C. Rate of effusion

D. Molar mass

Question 20

EasyPaper 2 · calculator1 mark

Which of the following species has more electrons than neutrons?

A. $^{56}_{26}Fe^{3+}$

B. $^{32}_{16}S^{2-}$

C. $^{127}_{53}I^{-}$

D. $^{23}_{11}Na^{+}$

9 more The nuclear atom questions in the app

Every answer is marked mark by mark, IB-style, and the AI tutor helps when you are stuck.

Where marks are lost

Reaching for "human error" or "only one trial." A source of error has to be a specific step in the method, not a general apology for the result.
Joining the dots instead of drawing a curve.
Naming a chemical instead of the property that distinguishes it, or vice versa. Answering with the nearest fact that comes to mind rather than the fact the command term and stem jointly ask for is a recurring way to answer a question that was not, quite, the one asked.

FAQ

Questions,
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Can't find what you're looking for? Email our student team.

What does The nuclear atom cover in IB Chemistry?

This topic introduces the nuclear atom model, including its subatomic particles and their arrangement. Atoms consist of a dense, positively charged nucleus (protons and neutrons) and negatively charged electrons occupying space outside the nucleus. Use the nuclear symbol ^A_ZX to deduce the number of protons, neutrons, and electrons in atoms and ions.

Is The nuclear atom SL or HL?

Both. SL and HL students study The nuclear atom, and HL goes further: 1.2.3 Mass spectra are used to determine relative atomic masses of elements from their isotopic composition. Students interpret mass spectra in terms of identity and relative abundance of isotopes.

How do I revise The nuclear atom for IB Chemistry?

Start from the core idea: this topic introduces the nuclear atom model, including its subatomic particles and their arrangement. In the exam: paper 1A carries the subatomic-particle counting. Weighted-average Ar calculations from isotopic abundance are standard 2-mark Paper 2 parts. Then practise exam-style questions, easiest first, writing out every step of your working before you check it.

How does FourtyFive help me practise The nuclear atom?

FourtyFive has 29 The nuclear atom questions. Every answer you write is marked mark by mark, IB-style, and you see where each mark was won or lost. Every part has a hint, the AI tutor helps you through the step you are stuck on, and your Study Profile picks what to practise next.

Is FourtyFive free for The nuclear atom practice?

Yes. A free account gives you 50 marked answers a month, and you do not need a card to sign up.

Can I handwrite The nuclear atom answers on an iPad?

Yes. In the FourtyFive iPad app you write your working by hand with Apple Pencil, the way you would on paper, and it is marked the same way.

The nuclear atom: notes and practice questions

How it is examined

Guiding questions

Linking questions

Practice questions

Question 1

Question 2

Question 3

Question 4

Question 5

Question 6

Question 7

Question 8

Question 9

Question 10

Question 11

Question 12

Question 13

Question 14

Question 15

Question 16

Question 17

Question 18

Question 19

Question 20

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Where marks are lost

Practise this topic as a session

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How it is examined

Guiding questions

Linking questions

Practice questions

Question 1

Question 2

Question 3

Question 4

Question 5

Question 6

Question 7

Question 8

Question 9

Question 10

Question 11

Question 12

Question 13

Question 14

Question 15

Question 16

Question 17

Question 18

Question 19

Question 20

9 more The nuclear atom questions in the app

Where marks are lost

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answered.

Start with the IB question
bank built for you.