Atomic Structure & The Periodic Table

Learn it by playing

Answer these questions to earn energy, then fish and explore. No account needed.

For teachers: ready-to-use lesson slides, revision notes, diagrams for Atomic Structure & The Periodic Table (Chemistry, CIE) — use them in your lesson, or run the topic as an interactive class activity your students play as a live game.

Lesson notes

Elements, Compounds & Mixtures

Element: substance made of atoms with the same number of protons; cannot be split chemically.
Compound: pure substance of two or more elements chemically combined; cannot be separated by physical means.
Mixture: combination of substances not chemically combined; separable by physical methods (e.g., filtration).
Examples: element = copper; compound = CO₂; mixture = sand and water.

Particle diagram showing elements, compounds and mixtures

Atomic Structure

Atoms consist of protons, neutrons (in nucleus) and electrons (in shells).
Proton: relative mass 1, charge +1; Neutron: relative mass 1, charge 0; Electron: relative mass 1/1840, charge -1.
Atomic number (Z) = number of protons; determines element and equals electrons in neutral atom.
Mass number (A) = total protons + neutrons; also called nucleon number.
Number of neutrons = mass number – atomic number.

The structure of the carbon atom

Electronic Configuration

Electrons occupy shells (energy levels); first shell holds 2, second 8, third 8 (simplified).
Electronic configuration lists electrons per shell, e.g., carbon = 2,4.
Outermost shell (valence shell) determines chemical properties; full outer shell = stable (noble gas).
Number of occupied shells = Period number; number of outer electrons = Group number (for Groups I–VII).
Ions: e.g., Na⁺ has configuration 2,8 (lost one electron).

Bohr model of a sodium atom showing nucleus with 11 protons and 12 neutrons, and electron shells 2,8,1.

Isotopes

Isotopes: same element, same number of protons, different number of neutrons.
Isotopes have identical chemical properties (same outer electrons) but different physical properties (mass).
Notation: e.g., carbon-14 or ¹⁴C.

The structure of a hydrogen-2 (deuterium) atom

Relative Atomic Mass (Extended)

Relative atomic mass (Aᵣ) = weighted average mass of all isotopes compared to 1/12 mass of carbon-12.
Formula: Aᵣ = (Σ(% abundance × mass)) / 100.
Example: rubidium: (72×85 + 28×87)/100 = 85.6.

Periodic Table & Groups

Elements in same Group have same number of outer electrons and similar chemical properties.
Noble gases (Group 0/VIII) have full outer shells and are unreactive.
Group number for Groups I–VII equals number of outer electrons.
Period number equals number of occupied electron shells.

The Periodic Table showing groups and periods

Slides

Step through every slide for this topic — plus flashcards and revision notes — with a free account.

Practice questions

Free preview — 8 of 54 questions. Sign up to see them all.

1.Which option correctly describes the relative charges and masses of the subatomic particles?
Easy
- AProton +1, neutron 0, electron -1; relative mass of proton 1, neutron 1, electron 0.00054
- BProton +1, neutron 0, electron -1; relative mass of proton 0.00054, neutron 1, electron 0
- CProton 0, neutron +1, electron -1; relative mass of proton 1, neutron 1, electron 0.00054
- DProton +1, neutron 0, electron 0; relative mass of proton 1, neutron 1, electron 0.00054
2.The atomic number of element Q is 9 and its mass number is 19. In which group of the Periodic Table should element Q be placed?
Easy
- AGroup 0
- BGroup I
- CGroup VII
- DGroup II
3.The diagram shows the atomic structure of an element. Which element is it?
Easy
- ACarbon
- BBeryllium
- COxygen
- DBoron
4.Which two atoms are isotopes?
Medium
- AQ and S
- BQ and T
- CR and T
- DR and S
5.Which of the following statements is correct?
Easy
- AElements contain different atoms
- BCompounds consist of elements that are not chemically combined
- CMixtures consist of elements that are chemically combined
- DA mixture can contain elements and compounds
6.Which statement about carbon is correct?
Medium
- AIt has 4 electron shells.
- BIt has 2 outer shell electrons.
- CIt has 12 nucleons.
- DIt has an electron configuration of 2,8,2.
7.Two atoms, X and Y can be represented as shown: ³₇X and ³₈Y. Which row is correct for both atoms?
Medium
- Aelectron configuration of X: 2,1; electron configuration of Y: 2,1; Is Y an isotope of X? Yes
- Belectron configuration of X: 2,1; electron configuration of Y: 2,6; Is Y an isotope of X? Yes
- Celectron configuration of X: 2,5; electron configuration of Y: 2,1; Is Y an isotope of X? No
- Delectron configuration of X: 2,5; electron configuration of Y: 2,6; Is Y an isotope of X? No
8.Element X contains 12 of each sub-atomic particle. What is the correct Group number for element X?
Medium
- AGroup 0
- BGroup I
- CGroup VII
- DGroup II

More questions

9.The X⁺ ion of element X has 16 electrons and a nucleon number of 37. What is the correct Group number for element X?
Hard
- AVII
- BVIII
- CIII
- DI
10.Which row correctly describes the number of outer shell electrons and properties of isotopes?
Medium
- ANumber of electrons: same; Chemical properties: same
- BNumber of electrons: same; Chemical properties: different
- CNumber of electrons: different; Chemical properties: same
- DNumber of electrons: different; Chemical properties: different
11.Iridium has two isotopes, Ir-191 and Ir-193. Calculate the relative atomic mass of iridium using the data: mass number 191 abundance 62.7%, mass number 193 abundance 37.3%.
Medium
- A191.2
- B191.6
- C191.7
- D192.5
12.A selenide ion has the notation ³⁴₇₉Se²⁻. Which row correctly describes the subatomic particles in a selenide ion?
Medium
- AProtons: 79, Neutrons: 34, Electrons: 34
- BProtons: 34, Neutrons: 45, Electrons: 34
- CProtons: 34, Neutrons: 45, Electrons: 36
- DProtons: 45, Neutrons: 34, Electrons: 32
13.A sample of neon consists of three isotopes: Ne-20 (90.9%), Ne-21 (0.3%), and Ne-22 (8.8%). What is the relative atomic mass of neon to one decimal place?
Medium
- A20.2
- B20.0
- C20.9
- D21.0
14.The diagram shows the atomic structure of an element. The nucleus contains 11 protons and 12 neutrons. The electron shells contain 2, 8, and 1 electrons respectively. Which element is it?
Easy
- ASodium
- BMagnesium
- CNeon
- DPotassium
15.An atom of element X has an electronic configuration of 2,8,6. Which group of the Periodic Table does element X belong to?
Easy
- AGroup VI
- BGroup II
- CGroup VIII
- DGroup VII
16.Copper has two isotopes: Cu-63 and Cu-65. The relative abundance of Cu-63 is 69%. What is the relative atomic mass of copper?
Medium
- A63.6
- B64.0
- C64.4
- D65.0
17.The diagram shows the electronic structure of an atom. There are 2 electrons in the first shell, 8 in the second, and 2 in the third. What is the atomic number of this element?
Easy
- A12
- B10
- C20
- D2
18.Which statement about isotopes is correct?
Easy
- AIsotopes have the same number of protons but different numbers of neutrons.
- BIsotopes have the same number of neutrons but different numbers of protons.
- CIsotopes have the same number of protons and the same number of neutrons.
- DIsotopes have different numbers of protons and different numbers of neutrons.
19.The relative atomic mass of chlorine is 35.5. Which statement explains this value?
Medium
- AChlorine exists as two isotopes with different masses, and their average is 35.5.
- BChlorine atoms have 35.5 protons and neutrons on average.
- CChlorine has a mass number of 35.5.
- DChlorine-35 and chlorine-37 have equal abundances.
20.A sample of rubidium contains two isotopes: Rb-85 (72%) and Rb-87 (28%). Calculate the relative atomic mass of rubidium to one decimal place.
Medium
- A85.6
- B86.0
- C85.0
- D86.6
21.The particle diagram shows a mixture of two compounds. Which statement is correct?
Medium
- AThe diagram shows two different types of molecules, each made of two different atoms.
- BThe diagram shows atoms of two different elements.
- CThe diagram shows a single compound.
- DThe diagram shows a mixture of elements.
22.An atom has the symbol ⁴⁰₁₈Ar. How many neutrons does it have?
Easy
- A22
- B18
- C40
- D58
23.The table shows the numbers of protons, neutrons, and electrons in four particles. Which two particles are isotopes of the same element? Particle P: protons 6, neutrons 6, electrons 6 Particle Q: protons 8, neutrons 7, electrons 8 Particle R: protons 7, neutrons 7, electrons 7 Particle S: protons 6, neutrons 8, electrons 6
Medium
- AP and Q
- BP and R
- CQ and R
- DP and S
24.The electronic configuration of a calcium ion (Ca²⁺) is:
Medium
- A2,8,8
- B2,8,8,2
- C2,8,8,1
- D2,8
25.A student measures the mass of a sample of sulfur powder before and after heating it in air. The mass increases. Which statement explains this observation?
Medium
- ASulfur has combined with oxygen from the air to form a compound.
- BSulfur has decomposed into simpler substances.
- CThe heating has caused the sulfur atoms to gain protons.
- DThe sulfur has evaporated and then condensed.
26.The diagram shows the atomic structure of an atom of element X. The nucleus contains 11 protons and 12 neutrons. The electron shells contain 2, 8, and 1 electrons respectively. Which statement about element X is correct?
Medium
- AX has an electronic configuration of 2,8,1 and is in Group I.
- BX has an electronic configuration of 2,8,1 and is in Period 1.
- CX has an electronic configuration of 2,8 and is in Group I.
- DX has an electronic configuration of 2,8,2 and is in Group II.
27.The table shows the numbers of protons, neutrons, and electrons in four particles. Which two particles are isotopes of the same element? Particle P: protons 6, neutrons 6, electrons 6 Particle Q: protons 7, neutrons 7, electrons 7 Particle R: protons 6, neutrons 8, electrons 6 Particle S: protons 8, neutrons 8, electrons 8
Medium
- AP and R
- BQ and S
- CP and Q
- DR and S
28.Which of the following statements about the relative charge and mass of subatomic particles is correct?
Easy
- AProton: charge +1, relative mass 1; Neutron: charge 0, relative mass 1; Electron: charge -1, relative mass 1/1840
- BProton: charge +1, relative mass 1/1840; Neutron: charge 0, relative mass 1; Electron: charge -1, relative mass 1
- CProton: charge +1, relative mass 1; Neutron: charge +1, relative mass 1; Electron: charge -1, relative mass 1/1840
- DProton: charge 0, relative mass 1; Neutron: charge +1, relative mass 1; Electron: charge -1, relative mass 1/1840
29.In a solid, particles are arranged in a regular pattern and vibrate about fixed positions. In a liquid, particles are close together but arranged randomly, able to move past each other. In a gas, particles are far apart, arranged randomly, and move quickly in random directions. Which state of matter is described by the first sentence?
Easy
- ASolid
- BLiquid
- CGas
- DAll three
30.In an experiment, a student heats a blue hydrated copper(II) sulfate crystals in a test tube. The crystals turn white and water droplets appear on the cooler parts of the test tube. Which type of change has occurred?
Medium
- AA reversible chemical change
- BAn irreversible chemical change
- CA physical change only
- DA nuclear change
31.Which of the following is the correct definition of an element?
Easy
- AA substance made of atoms that all contain the same number of protons and cannot be split into anything simpler by chemical means.
- BA substance made of two or more different types of atoms chemically combined.
- CA combination of two or more substances that are not chemically combined.
- DA substance that can be separated into simpler substances by physical methods.
32.Which particle has a relative mass of 1 and a charge of 0?
Easy
- AProton
- BNeutron
- CElectron
- DNucleus
33.What is the electronic configuration of a sulfur atom?
Easy
- A2,8,6
- B2,8,8
- C2,6
- D2,8,8,6
34.An atom of element X has 12 protons and 12 neutrons. What is its mass number?
Easy
- A12
- B24
- C36
- D6
35.Beryllium has atomic number 4 and mass number 9. Which set of numbers correctly describes its atomic structure?
Medium
- AA nucleus with 4 protons and 5 neutrons, and two electron shells: first shell with 2 electrons, second shell with 2 electrons.
- BA nucleus with 4 protons and 4 neutrons, and two electron shells: first shell with 2 electrons, second shell with 2 electrons.
- CA nucleus with 4 protons and 5 neutrons, and two electron shells: first shell with 2 electrons, second shell with 4 electrons.
- DA nucleus with 5 protons and 4 neutrons, and two electron shells: first shell with 2 electrons, second shell with 3 electrons.
36.An atom has the electronic configuration 2,8,7. Which group of the Periodic Table does it belong to?
Easy
- AGroup VII
- BGroup II
- CGroup 0
- DGroup I
37.Which of the following is a mixture?
Easy
- ACarbon dioxide
- BBrass
- CWater
- DSodium chloride
38.A sample of lithium contains two isotopes: Li-6 (7.5%) and Li-7 (92.5%). What is the relative atomic mass of lithium to one decimal place?
Medium
- A6.9
- B6.5
- C7.0
- D6.1
39.The diagram shows the atomic structure of an atom. The nucleus contains 11 protons and 12 neutrons. The electron shells contain 2, 8, and 1 electrons respectively. Which element is this?
Easy
- ASodium
- BMagnesium
- CNeon
- DPotassium
40.Which statement about an element is correct?
Easy
- AA substance made of atoms that all contain the same number of protons and cannot be split into anything simpler by chemical means
- BA substance made of two or more elements chemically combined
- CA combination of two or more substances that are not chemically combined
- DA substance that can be separated by physical methods
41.Compounds can be separated into their elements by physical means such as filtration or evaporation.
Easy
True or false?
42.The electronic configuration of an atom is 2,8,7. Which group of the Periodic Table does it belong to?
Easy
- AGroup 2
- BGroup 7
- CGroup 8
- DGroup 17
43.Match each particle with its relative charge.
Easy
- Proton
- Neutron
- Electron
- 1+
- 0
- 1-
44.Arrange the following electron shells in order of increasing energy (lowest energy first).
Easy
- Third shell
- First shell
- Second shell
45.Which of the following are true about isotopes? (Select all that apply)
Medium
- AThey have the same number of protons but different numbers of neutrons.
- BThey have the same chemical properties.
- CThey have the same physical properties.
- DThey have the same number of electrons in their outer shells.
46.The relative atomic mass of an element is always a whole number.
Easy
True or false?
47.Match each subatomic particle with its relative charge.
Easy
- Proton
- Neutron
- Electron
- 1+
- 0
- 1−
48.The table shows the numbers of protons, neutrons, and electrons in four particles. Which two particles are isotopes of the same element? Particle P: protons 6, neutrons 6, electrons 6 Particle Q: protons 6, neutrons 8, electrons 6 Particle R: protons 7, neutrons 7, electrons 7 Particle S: protons 8, neutrons 8, electrons 8
Medium
- AP and Q
- BP and R
- CQ and S
- DR and S
49.Complete the sentence.
Easy
The relative mass of an electron is ____.
50.A sample of lithium contains two isotopes: Li-6 (7.5%) and Li-7 (92.5%). Calculate the relative atomic mass of lithium to one decimal place.
Medium
51.What is the name given to the total number of protons and neutrons in an atom?
Easy
52.Boron has two isotopes: B-10 with a mass of 10.013 amu and abundance 19.9%, and B-11 with a mass of 11.009 amu and abundance 80.1%. Calculate the relative atomic mass of boron to two decimal places.
Medium
53.State the meaning of the term 'isotopes'.
Easy
54.Boron has two isotopes: B-10 with a mass of 10.013 amu and abundance 19.9%, and B-11 with a mass of 11.009 amu and abundance 80.1%. Calculate the relative atomic mass of boron to two decimal places.
Medium
- A9.81
- B11.81
- C12.81
- D10.81

Unlock all 54 questions & more

Create a free account to see every question, the slides, flashcards and revision notes for this topic.

Past papers

Past-paper practice for this topic is coming soon.

Coming soon