Chemistry 9701 · AS & A Level
Atomic structure
100 practice questions on Atomic structure, with worked solutions and instant marking.
Which ion contains more electrons than protons, but also more protons than neutrons? $[\text{H} = ^1_1\text{H};\ \text{D} = ^2_1\text{H};\ \text{O} = ^{16}_8\text{O}]$
Feb/March 2016
Which species has the fewest electrons?
Feb/March 2016
Which ion has an electronic configuration that is the same as $\text{Cl}^-$?
Feb/March 2017
Water for drinking may have dissolved calcium hydrogencarbonate, $\text{Ca(HCO}_3)_2$. How many electrons does a hydrogencarbonate anion contain?
Feb/March 2018
Which of the following statements about a $3p$ orbital is correct?
Feb/March 2019
Which of the following pairs contain species that each have the same count of unpaired electrons in $p$ orbitals?
Feb/March 2019
How many protons, neutrons and electrons are there in the ion $^{54}_{26}\text{Fe}^{3+}$?
Feb/March 2020
The table gives the numbers of protons, neutrons and electrons in four different particles, W, X, Y and Z. Which pair represents atoms of two isotopes of the same element?
Feb/March 2021
What electronic configuration does $\mathrm{Mg}^{2+}$ have?
Feb/March 2022
Which atom has four times as many neutrons as the $^{7}_{3}\text{Li}$ atom?
Feb/March 2023
Which species has the same number of neutrons as $^{14}_{6}\text{C}$ and the same number of electrons as $^{23}_{11}\text{Na}^+$?
Feb/March 2024
Organic compound X has empirical formula $\text{C}_2\text{H}_4\text{O}$. Compound X is reduced by $\text{LiAlH}_4$, but it is not reduced by $\text{NaBH}_4$. What is compound X?
Feb/March 2025
An ion carrying a charge of $2-$ has $10$ electrons and $14$ neutrons. What is the nucleon number of this ion?
Feb/March 2025
What proton number could an element have if each of its atoms has three unpaired electrons?
May/June 2010
The Data Booklet may be needed for this question. What might the proton number be of an element whose atoms each contain three unpaired electrons?
May/June 2010
For this question, the Data Booklet may be useful. What could the proton number be for an element whose atoms each have three unpaired electrons?
May/June 2010
Which equation shows the second ionisation energy of an element X?
May/June 2011
Helium, $\text{He}$, is the second element in the Periodic Table. Tritium is the isotope of hydrogen $^3_1\text{H}$. What is the same between an atom of $^4_2\text{He}$ and an atom of $^3_1\text{H}$?
May/June 2011
Which equation shows the second ionisation energy of an element X?
May/June 2011
The Data Booklet is needed for this question. In which pair do both species contain the same number of unpaired $p$ electrons?
May/June 2012
Calcium has a second ionisation energy of $1150\ \text{kJ mol}^{-1}$. Which equation correctly shows this statement?
May/June 2012
The following two conversions are given. $\text{NH}_4^+ \rightarrow \text{NH}_3$ $\text{C}_2\text{H}_4 \rightarrow \text{C}_2\text{H}_6$ What common feature is shared by these two conversions?
May/June 2012
For which species are the numbers of protons, neutrons and electrons all unequal?
May/June 2012
Aluminium has a third ionisation energy of $2740\,\text{kJ mol}^{-1}$. Which option gives the correct representation of this statement?
May/June 2012
Organic compound J reacts with sodium, forming an organic ion with charge $-3$. J also reacts with $\text{NaOH(aq)}$ to form an organic ion with charge $-1$. What might be the structural formula of J?
May/June 2012
For calcium, the second ionisation energy is $1150\,\text{kJ mol}^{-1}$. Which equation shows this statement correctly?
May/June 2012
The Data Booklet may be needed for this question. Which pair contains species that each have the same number of unpaired $p$ electrons?
May/June 2012
For which species do the numbers of protons, neutrons and electrons all differ?
May/June 2013
Which ion contains more electrons than protons, and more protons than neutrons? [$\text{H} = ^{1}_{1}\text{H};\ \text{D} = ^{2}_{1}\text{H};\ \text{O} = ^{16}_{8}\text{O}$]
May/June 2013
Which of the pairs below contains two species with the same count of unpaired $p$ electrons?
May/June 2013
Use of the Data Booklet is relevant for this question. For which species are the counts of protons, neutrons and electrons all different?
May/June 2013
The Data Booklet is needed for this question. Which statements are correct for the atoms $^{23}\text{Na}$ and $^{24}\text{Mg}$?
May/June 2013
The Data Booklet is relevant for this question. Atoms of element X contain six unpaired electrons. Which element could X be?
May/June 2014
For this question, the Data Booklet may be used. The isotope $^{99}\text{Tc}$ is radioactive and has been detected in lobsters and seaweed near nuclear fuel reprocessing plants. Which of the following statements about an atom of $^{99}\text{Tc}$ are correct?
May/June 2015
Which option shows all three particles having the same electronic configuration and the same number of neutrons?
May/June 2015
Which of the following statements concerning the phosphide ion, $^{31}_{15}\text{P}^{3-}$, and the chloride ion, $^{35}_{17}\text{Cl}^-$, are correct?
May/June 2015
The technetium-99 isotope, $^{99}\text{Tc}$, is radioactive and has been detected in lobsters and seaweed close to nuclear fuel reprocessing plants. Which of the following statements about an atom of $^{99}\text{Tc}$ are correct?
May/June 2015
$X$ is a particle that contains 18 electrons and 20 neutrons. Which symbol could represent $X$?
May/June 2016
During nuclear reactions, the products formed are not the same elements as those that have reacted. These changes are shown using nuclear equations, for example the one below. $^{235}_{92}\text{U} + ^1_0\text{n} \rightarrow ^{144}_{56}\text{Ba} + ^{89}_{36}\text{Kr} + 3^1_0\text{n}$ The total nucleon (mass) number remains 236, and the total proton number stays 92. In a different nuclear reaction, uranium-238 is made to react with deuterium atoms, $^2_1\text{H}$. An isotope of a new element, J, is produced together with two neutrons. $^{238}_{92}\text{U} + ^2_1\text{H} \rightarrow \text{J} + 2^1_0\text{n}$ Which isotope is J?
May/June 2016
Four electronic configurations are given below. Three of these configurations are for atoms of the elements chlorine, sodium and vanadium. Which electronic configuration is for an atom of a different element?
May/June 2016
Copper has a relative atomic mass of $63.5$. Which chart shows a correct mass spectrum that would give this value?
May/June 2016
Which single atom in the gaseous state contains a total of five electrons in spherically shaped orbitals?
May/June 2016
A beam of charged particles is bent by an electric field. When the conditions are the same, the angle through which a particle is deflected is proportional to its charge/mass ratio. In one experiment, protons are deflected through an angle of $+15^{\circ}$. In a second experiment under the same conditions, particle Y is deflected through an angle of $-5^{\circ}$. What could particle Y consist of?
May/June 2017
For which species are the numbers of protons, neutrons and electrons all different?
May/June 2017
For a single gaseous atom of element X, at least one of the $3d$ orbitals contains a pair of electrons, and the $4s$ subshell is full. What is the possible identity of element X?
May/June 2017
The ion $\text{Y}^{3-}$ has 18 electrons and a mass number of 31. How many protons and neutrons are present in $\text{Y}^{3-}$?
May/June 2017
Which statements concerning the atoms $^{23}_{11}\text{Na}$ and $^{24}_{12}\text{Mg}$ are correct?
May/June 2017
The two conversions below are shown. $\text{NH}_4^+ \rightarrow \text{NH}_3$ $\text{C}_2\text{H}_4 \rightarrow \text{C}_2\text{H}_6$ What common feature do these two conversions share?
May/June 2017
This question concerns isolated gaseous atoms. Which atom has every electron paired?
May/June 2018
The electronic configuration of a sulfur atom is $1s^2 2s^2 2p^6 3s^2 3p^4$. In one sulfur atom, how many electrons are in the valence shell, and how many electrons are unpaired?
May/June 2018
Which pairs contain species with the same number of electrons?
May/June 2018
A beam of neutrons is sent through an electric field. The mass of a single neutron, compared with $\frac{1}{12}$ of the mass of a $^{12}\text{C}$ atom, and any deflection produced by the electric field are recorded. Which row is correct?
May/June 2018
The table shows the electron arrangement in the second shell of an atom that has eight protons. Which row is correct for this atom?
May/June 2018
A sample of element X is examined by mass spectrometry. The mass spectrum produced is shown. What is the relative atomic mass of this sample of element X?
May/June 2019
A calcium-48 atom can produce a $2+$ ion. Which of these statements about the ion are correct?
May/June 2019
The outer electron in a neon atom is found in a specific orbital. Which row gives the orbital’s relative energy and shape?
May/June 2019
The eight elements from sodium through to argon are all in the same period of the Periodic Table. The equation for the first ionisation energy is given below. $\text{X}(g) \rightarrow \text{X}^+(g) + e^-$ Which one of these eight elements has the electron in this equation taken from a filled orbital?
May/June 2019
Which statements regarding an atom of $^{99}\text{Tc}$ are correct?
May/June 2019
Which atom contains exactly three unpaired electrons?
May/June 2019
Which statements about the $^{209}_{83} \text{Bi}$ atom are correct?
May/June 2019
When looking at the two common isotopes of chlorine, which statements are correct?
May/June 2019
For which pair does every species have the same number of unpaired electrons?
May/June 2020
Which particle contains the same number of protons as neutrons and has the electronic structure of $1s^2 2s^2 2p^6 3s^2 3p^6$?
May/June 2020
What is the electronic configuration of a lone $\text{Ni}^{2+}$ ion?
May/June 2020
Which pair of species has both members with only one unpaired p electron?
May/June 2021
Which equation shows the first ionisation energy of iodine?
May/June 2021
Which ions have the same number of electrons as neutrons?
May/June 2021
Which atom has the same total number of electrons as an ammonium ion?
May/June 2021
Which atom has its outermost electron in an orbital with the shape shown, with principal quantum number 3?
May/June 2022
Which atom has an electron count equal to that of the hydroxide ion, $\text{OH}^-$?
May/June 2022
This question concerns isolated gaseous atoms in their ground state. In which atom are all of the electrons paired?
May/June 2022
Which atom has precisely three unpaired electrons in its ground state?
May/June 2022
A sample of sulfur is made up mainly of $^{32}\text{S}$. It also includes $4.2\%$ $^{34}\text{S}$ and $2.8\%$ $^{36}\text{S}$. There are no further isotopes of sulfur in the sample. Calculate the relative atomic mass, $A_r$, of this sulfur sample.
May/June 2022
Element X contains six more protons than element Y. Which statement has to be correct?
May/June 2023
During analysis of chlorine gas using a mass spectrometer, $^{35}\text{Cl}^+$ ions are detected. Which row is correct?
May/June 2023
The diagram gives the relative amounts of the various isotopes of lead present in a sample of lead ore. The abundance of 208 is half the abundance of 206. The abundances of 208 and 209 are the same. What is the relative atomic mass of the lead in the sample?
May/June 2023
Which statement concerning $^{131}_{53}\text{I}$ is correct?
May/June 2024
How many protons, neutrons and electrons are there altogether in an ammonium ion with a relative formula mass of $21$?
May/June 2024
Which of the following statements about a $3p$ orbital is correct?
May/June 2025
A helium ion has two protons, two neutrons and one electron. This helium ion and a proton are each sent separately through a uniform electric field. The particles move at the same velocity. Which arrow shows the path of each particle?
May/June 2025
How many neutrons are present in an iron atom that has a mass number of 60?
May/June 2025
Which uncombined gaseous atom contains a total of five electrons in spherically shaped orbitals?
May/June 2025
The diagram displays the logarithm of the first 13 ionisation energies for an element. Which statement is correct?
May/June 2025
An ion $X^+$ has eight protons. What electronic configuration does $X^+$ have?
Oct/Nov 2010
Which ion contains more electrons than protons, and more protons than neutrons? [$\text{H} = {^1_1}\text{H}$; $\text{D} = {^2_1}\text{H}$; $\text{O} = {^{16}_8}\text{O}$]
Oct/Nov 2010
A monatomic ion $X^+$ has eight protons. What is the electronic configuration of $X^+$?
Oct/Nov 2010
Which ion contains a greater number of electrons than protons, and a greater number of protons than neutrons? $[\text{H} = ^1_1\text{H};\; \text{D} = ^2_1\text{H};\; \text{O} = ^{16}_8\text{O}]$
Oct/Nov 2010
Which element has the same number of electron pairs as unpaired electrons in orbitals with principal quantum number $2$?
Oct/Nov 2011
The meanings of many chemical terms can be shown by chemical equations. Which terms can be shown by an equation that illustrates the formation of a positive ion?
Oct/Nov 2011
Which element possesses the same number of electron pairs as unpaired electrons in orbitals with principal quantum number $2$?
Oct/Nov 2011
You may need to refer to the Data Booklet for this question. The $^{68}\text{Ge}$ isotope is medically useful because it undergoes a natural radioactive process to form a gallium isotope, $^{68}\text{Ga}$, which is used to detect tumours. This change in $^{68}\text{Ge}$ happens when an electron is captured by the nucleus, converting a proton into a neutron. Which statement about the composition of an atom of the $^{68}\text{Ga}$ isotope is correct?
Oct/Nov 2012
But-2-ene-1,4-diol is transformed in two stages, passing through an intermediate X, to form ketobutanedioic acid. $\text{HOCH}_2\text{CH}=\text{CHCH}_2\text{OH} \xrightarrow[\text{step 1}]{} X \xrightarrow[\text{step 2}]{\text{hot acidified } \text{KMnO}_4} \text{HO}_2\text{CCOCH}_2\text{CO}_2\text{H}$ What reagent might be used in step 1, and what is intermediate X?
Oct/Nov 2012
The isotope $^{99}\text{Tc}$ is radioactive and has been detected in lobsters and seaweed near nuclear fuel reprocessing plants. Which of the following statements about an atom of $^{99}\text{Tc}$ are correct?
Oct/Nov 2012
John Dalton’s atomic theory, first published in 1808, put forward four predictions about atoms. Which one of these predictions is still accepted as correct?
Oct/Nov 2012
The $^{68}\text{Ge}$ isotope has medical applications because it naturally decays to form the gallium isotope, $^{68}\text{Ga}$, which is used for detecting tumours. In this conversion of $^{68}\text{Ge}$, an electron is captured by the nucleus, so a proton changes into a neutron. Which statement about the composition of an atom of the $^{68}\text{Ga}$ isotope is correct?
Oct/Nov 2012
Which reagent is able to react with ethanol and also with ethanoic acid?
Oct/Nov 2012
The isotope $^{99}\text{Tc}$ is radioactive and has been detected in lobsters and seaweed near nuclear fuel reprocessing plants. Which statements about an atom of $^{99}\text{Tc}$ are correct?
Oct/Nov 2012
John Dalton’s atomic theory, published in 1808, included four predictions about atoms. Which of these predictions is still regarded as correct?
Oct/Nov 2012
Which sub-atomic particles are present in the same number in the phosphide ion $^{31}_{15}\text{P}^{3-}$ and the sulfide ion $^{32}_{16}\text{S}^{2-}$?
Oct/Nov 2012
X is a particle that has 18 electrons and 20 neutrons. Which symbol could represent X?
Oct/Nov 2013