Atomic Structure questions

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Atomic Structure question collection

Review Atomic Structure questions for Chemistry, with correct answers shown and coverage across protons, neutrons and electrons; atomic number and mass number; isotopes and relative atomic mass.

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Question 1

Which statement about atom structure is correct?
  1. Almost all the mass is concentrated in the nucleus
  2. Most of the mass is in electron shells
  3. Protons orbit around electrons
  4. Neutrons are negatively charged

Question 2

Which experiment led to the nuclear model of the atom?
  1. Rutherford's alpha-scattering experiment
  2. Thomson's cathode-ray experiment
  3. Bohr's study of line spectra
  4. Dalton's measurements of reacting masses

Question 3

An atom has atomic number \(12\) and mass number \(24\). How many neutrons does it have?
  1. \(12\)
  2. \(24\)
  3. \(6\)
  4. \(36\)

Question 4

For chlorine isotopes \(35\) (\(75\%\)) and \(37\) (\(25\%\)), what is the relative atomic mass?
  1. \(35.5\)
  2. \(36.0\)
  3. \(35.0\)
  4. \(36.5\)

Question 5

What is the electronic structure of sodium (atomic number \(11\))?
  1. \(2,8,1\)
  2. \(2,8,2\)
  3. \(2,7,2\)
  4. \(2,9\)

Question 6

What is the electronic structure of calcium (atomic number \(20\))?
  1. \(2,8,8,2\)
  2. \(2,8,8,1\)
  3. \(2,8,10\)
  4. \(2,10,8\)

Question 7

Why do elements in the same group have similar reactions?
  1. They have the same number of outer-shell electrons
  2. They have the same number of neutrons
  3. They all have the same mass number
  4. They have identical numbers of shells

Question 8

What charge does a sodium ion have after losing one electron?
  1. \(+1\)
  2. \(-1\)
  3. \(+2\)
  4. \(0\)

Question 9

What is the electron arrangement of a chloride ion, Cl-?
  1. \(2,8,8\)
  2. \(2,8,7\)
  3. \(2,7,8\)
  4. \(2,8,8,1\)

Question 10

What is the approximate radius of an atom?
  1. \(1 \times 10^{-10}\,\mathrm{m}\)
  2. \(1 \times 10^{-6}\,\mathrm{m}\)
  3. \(1 \times 10^{-14}\,\mathrm{m}\)
  4. \(1 \times 10^{-2}\,\mathrm{m}\)

Question 11

The nucleus has a radius of about \(1 \times 10^{-14}\,\mathrm{m}\). Compared with the atom, this is roughly?
  1. \(\frac{1}{10{,}000}\) of the atomic radius
  2. \(\frac{1}{10}\) of the atomic radius
  3. The same size as the atom
  4. \(10\) times larger than the atom

Question 12

What is the relative mass of an electron compared with a proton?
  1. Very small, about \(\frac{1}{1836}\)
  2. Exactly \(1\)
  3. About \(1836\)
  4. Exactly \(0\)

Question 13

How does Group 1 reactivity change down the group?
  1. It increases
  2. It decreases
  3. It stays constant
  4. It alternates every element

Question 14

How does Group 7 reactivity change down the group?
  1. It decreases
  2. It increases
  3. It stays constant
  4. It doubles each period

Question 15

Which electron arrangement makes Group 0 elements unreactive?
  1. A stable full outer shell
  2. One outer electron to lose
  3. Seven outer electrons to gain
  4. A partly filled outer shell

Question 16

Which halogen can displace bromine from potassium bromide solution?
  1. Chlorine
  2. Iodine
  3. Astatine
  4. Neon

Question 17

What was the key limitation of Dalton's early atomic model?
  1. It did not include subatomic particles
  2. It included too many electron shells
  3. It showed a full nuclear model
  4. It predicted isotopes accurately

Question 18

A sample has \(60\%\) isotope X-\(20\) and \(40\%\) isotope X-\(22\). What is the relative atomic mass?
  1. \(20.8\)
  2. \(21.0\)
  3. \(20.0\)
  4. \(22.0\)

Question 19

Aluminium-\(27\) forms Al3+. How many electrons are in Al3+?
  1. \(10\)
  2. \(13\)
  3. \(14\)
  4. \(27\)

Question 20

Why did scientific models of the atom change over time?
  1. New evidence revealed limits in earlier models
  2. Simpler drawings became more fashionable
  3. Periodic-table layouts required new models
  4. Atoms changed structure between experiments

Question 21

What is relative atomic mass?
  1. Weighted mean mass of an element's isotopes
  2. The number of protons
  3. The mass of one atom in grams
  4. The number of shells

Question 22

Which particles are counted in an atom's mass number?
  1. Protons and neutrons
  2. Protons only
  3. Neutrons only
  4. Protons and electrons

Question 23

What happens when an atom loses an electron?
  1. It forms a positive ion
  2. It forms a negative ion
  3. It becomes a neutron
  4. It gains a proton

Question 24

What forms when an atom gains an electron?
  1. A negative ion
  2. A positive ion
  3. A different isotope
  4. The next element

Question 25

What does Group 1 in the periodic table show?
  1. Elements with one electron in the outer shell
  2. Elements with one proton in each nucleus
  3. Elements with one neutron in each nucleus
  4. Elements with a full outer electron shell

Question 26

Why do Group 1 metals become more reactive down the group?
  1. The outer electron is easier to lose
  2. The outer electron is harder to lose
  3. The nucleus loses positive charge
  4. The atoms need to gain an electron

Question 27

What charge does a Group 7 atom have after gaining one electron?
  1. 1−
  2. 1+
  3. 2−
  4. 0

Question 28

Which atomic model placed electrons within a sphere of positive charge?
  1. The plum-pudding model
  2. Dalton's solid-sphere model
  3. Rutherford's nuclear model
  4. Bohr's shell model

Question 29

Which property orders elements in the modern periodic table?
  1. Atomic number
  2. Relative atomic mass
  3. Number of electron shells
  4. State at room temperature

Question 30

Where are transition metals in the periodic table?
  1. In the centre
  2. At the far left
  3. At the far right
  4. Across the top row

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Review Atomic Structure questions for Chemistry, with correct answers shown and coverage across protons, neutrons and electrons; atomic number and mass number; isotopes and relative atomic mass.

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