Sample Quizzes For Preparation: Atomic Structure

AS Level Chemistry – Chapter 1: Atomic Structure Quiz

Question 1: What occupies most of the volume of an atom?

A. Nucleus
B. Protons
C. Electrons
D. Neutrons

Question 2: Which subatomic particle has no charge?

A. Proton
B. Electron
C. Neutron
D. Positron

Question 3: What is the relative mass of a proton?

A. 1
B. 0
C. 1/1836
D. 2

Question 4: What is the atomic number of an element?

A. Number of neutrons
B. Number of protons
C. Number of electrons in an ion
D. Number of protons + neutrons

Question 5: Which statement is correct about a neutral atom?

A. Protons > electrons
B. Electrons = neutrons
C. Protons = electrons
D. Protons = neutrons

Question 6: Which particle will not be deflected in an electric field?

A. Electron
B. Proton
C. Neutron
D. Alpha particle

Question 7: How many protons, neutrons and electrons are in ³⁹₁₉K⁺?

A. 19 p, 20 n, 18 e
B. 19 p, 20 n, 19 e
C. 20 p, 19 n, 18 e
D. 18 p, 20 n, 19 e

Question 8: What causes the atomic radius to decrease across a period?

A. More shielding
B. Increase in electron shells
C. Increase in nuclear charge
D. Addition of neutrons

Question 9: Which species has the smallest radius?

A. Na
B. Na⁺
C. Mg
D. Mg²⁺

Question 10: Which species is an isotope of ⁶₃Li?

A. ⁷₃Li
B. ⁶₄Be
C. ⁷₂He
D. ⁶₃Na

Question 11: Why do isotopes of the same element have identical chemical properties?

A. Same neutron number
B. Same mass number
C. Same electron configuration
D. Same density

Question 12: Why do isotopes have different physical properties?

A. Different number of protons
B. Different number of electrons
C. Different number of neutrons
D. Different electron shells

Question 13: How many electrons are present in the 3p sub-shell of Cl (Z=17)?

A. 2
B. 4
C. 5
D. 6

Question 14: What is the electron configuration of Mg²⁺?

A. 1s² 2s² 2p⁶
B. 1s² 2s² 2p⁶ 3s²
C. [Ne] 3s²
D. 1s² 2s² 2p⁶ 3s¹

Question 15: What is the maximum number of electrons in the 3d sub-shell?

A. 6
B. 10
C. 5
D. 2

Question 16: Which orbital shape is spherical?

A. p
B. d
C. s
D. f

Question 17: Which orbital has a dumbbell shape?

A. s
B. p
C. d
D. f

Question 18: What does each box represent in an electron box diagram?

A. A sub-shell
B. A shell
C. An orbital
D. A pair of atoms

Question 19: What is a free radical?

A. A positively charged ion
B. A negatively charged atom
C. A species with unpaired electrons
D. A stable noble gas

Question 20: What is meant by first ionisation energy?

A. Energy needed to remove 1 mole of electrons from 1 mole of ions
B. Energy needed to remove 1 mole of protons
C. Energy required to remove 1 mole of electrons from gaseous atoms
D. Energy to add 1 mole of electrons

Question 21: Which trend is observed in first ionisation energy across a period?

A. Decreases
B. Increases
C. Remains constant
D. Fluctuates randomly

Question 22: Which trend is observed in first ionisation energy down a group?

A. Increases
B. Decreases
C. Fluctuates
D. Remains constant

Question 23: Why does ionisation energy decrease down a group?

A. Nuclear charge decreases
B. Shielding and atomic radius increase
C. Number of protons decreases
D. Electrons are removed from inner shells

Question 24: Which element shows a large jump between the second and third ionisation energies?

A. Mg
B. Al
C. Li
D. Na

Question 25: What does a large jump in successive ionisation energies indicate?

A. Electrons are removed from same shell
B. Electrons enter a d orbital
C. Electron removed from a closer inner shell
D. Ion has become neutral

Question 26: Which factor does NOT affect ionisation energy?

A. Nuclear charge
B. Shielding
C. Atomic radius
D. Boiling point

Question 27: What is the order of increasing sub-shell energy up to 4p?

A. 1s < 2s < 2p < 3p < 3s < 3d < 4s < 4p
B. 1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p
C. 1s < 2s < 3s < 2p < 4s < 3p < 3d < 4p
D. 1s < 2p < 2s < 3d < 3p < 3s < 4s < 4p

Question 28: What is the shorthand configuration of Fe (Z=26)?

A. [Ar] 3d⁶ 4s²
B. [Ne] 3s² 3p⁶ 3d⁶
C. [He] 2s² 2p⁶ 3s²
D. [Kr] 4d¹⁰ 5s²

Question 29: How many unpaired electrons are there in a neutral nitrogen atom?

A. 2
B. 1
C. 3
D. 0

Question 30: What does a sharp increase in ionisation energy between two successive electrons suggest?

A. Electrons from same shell
B. Electron removed from a more distant shell
C. Electron removed from a more strongly bound inner shell
D. Electron gained energy

Answer Key and Detailed Explanations – AS Level Chemistry: Chapter 1 Atomic Structure Quiz

1. C. Electrons
→ Electrons move in shells surrounding the nucleus and occupy most of the atom’s volume.

2. C. Neutron
→ Neutrons have no electrical charge.

3. A. 1
→ The relative mass of a proton is 1.

4. B. Number of protons
→ Atomic number defines the number of protons and the identity of the element.

5. C. Protons = electrons
→ In a neutral atom, positive and negative charges must be balanced.

6. C. Neutron
→ Neutrons have no charge, so they’re unaffected by electric fields.

7. A. 19 p, 20 n, 18 e
→ K has atomic number 19 and mass number 39. K⁺ has lost 1 electron.

8. C. Increase in nuclear charge
→ Nuclear charge pulls electrons closer, decreasing atomic radius across a period.

9. D. Mg²⁺
→ Mg²⁺ has the highest nuclear charge to electron ratio and smallest size.

10. A. ⁷₃Li
→ Same atomic number, different mass number → isotope.

11. C. Same electron configuration
→ Chemical properties depend on electrons, which are the same in all isotopes.

12. C. Different number of neutrons
→ Different mass and density arise from different neutron numbers.

13. D. 6
→ Cl has 17 electrons: 3p sub-shell is completely filled with 6 electrons.

14. A. 1s² 2s² 2p⁶
→ Mg²⁺ loses 2 electrons from 3s².

15. B. 10
→ 3d sub-shell has 5 orbitals, each can hold 2 electrons → 10 max.

16. C. s
→ s orbitals are spherical.

17. B. p
→ p orbitals are dumbbell-shaped.

18. C. An orbital
→ Each box in an orbital diagram represents a single orbital.

19. C. A species with unpaired electrons
→ Free radicals have at least one unpaired electron, making them highly reactive.

20. C. Energy required to remove 1 mole of electrons from gaseous atoms
→ This is the definition of first ionisation energy.

21. B. Increases
→ Greater nuclear charge and smaller radius make it harder to remove electrons across a period.

22. B. Decreases
→ Down a group, increased distance and shielding lower ionisation energy.

23. B. Shielding and atomic radius increase
→ More shells → greater distance and shielding → weaker attraction.

24. D. Na
→ Na has 1 outer electron; large jump from 1st to 2nd IE as the second is from a full shell.

25. C. Electron removed from a closer inner shell
→ Sharp IE increase = electron removed from lower energy shell closer to nucleus.

26. D. Boiling point
→ Boiling point does not influence ionisation energy.

27. B. 1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p
→ Standard filling order based on energy levels.

28. A. [Ar] 3d⁶ 4s²
→ Shorthand configuration for Fe using the noble gas [Ar].

29. C. 3
→ N (Z=7): 1s² 2s² 2p³ → three unpaired electrons in 2p.

30. C. Electron removed from a more strongly bound inner shell
→ Large IE jump indicates a new shell with stronger nuclear attraction.