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Secondary 3 Chemistry Periodic Table Quiz
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Questions
Secondary 3 Chemistry Quiz - Periodic Table
Name: ________________________
Class: ________________________
Date: ________________________
Score: _____ / 40
Duration: 45 minutes
Total Marks: 40
Instructions
- Answer all questions in the spaces provided.
- Show all working where applicable.
- The number of marks for each question is shown in brackets [ ].
- You may use a Periodic Table (provided separately) for reference.
- Write your answers clearly in ink. Pencil may be used for diagrams.
Section A: Multiple Choice (Questions 1–5) [10 marks]
For each question, choose the most correct answer and write the letter in the space provided.
1. Which of the following best describes the modern Periodic Table?
A. Elements are arranged in order of increasing relative atomic mass.
B. Elements are arranged in order of increasing atomic (proton) number.
C. Elements are arranged in order of increasing number of neutrons.
D. Elements are arranged alphabetically by element name.
Answer: ________ [1]
2. An element X has the electronic configuration 2.8.6. In which group and period of the Periodic Table is element X found?
A. Group 2, Period 3
B. Group 6, Period 3
C. Group 8, Period 3
D. Group 16, Period 2
Answer: ________ [1]
3. Which statement about elements in the same group of the Periodic Table is correct?
A. They have the same number of electron shells.
B. They have the same number of valence electrons.
C. They have the same atomic radius.
D. They have the same relative atomic mass.
Answer: ________ [1]
4. Going across Period 3 from sodium (Na) to argon (Ar), which trend is observed?
A. Atomic radius increases.
B. Ionisation energy decreases.
C. Electronegativity increases.
D. Metallic character increases.
Answer: ________ [1]
5. Which of the following elements is a noble gas?
A. Nitrogen
B. Chlorine
C. Krypton
D. Oxygen
Answer: ________ [1]
Section B: Short Answer (Questions 6–14) [15 marks]
6. Define the term period as used in the Periodic Table. [1]
7. An atom of element Y has 12 protons and 12 neutrons.
(a) State the atomic number of element Y. [1]
(b) State the mass number of element Y. [1]
(c) Identify element Y and state one use of this element. [2]
8. The table below shows the atomic radii of three consecutive elements in Period 3.
| Element | Atomic radius (nm) |
|---|---|
| P | 0.180 |
| Q | 0.160 |
| R | 0.143 |
(a) Explain why the atomic radius decreases from P to R. [2]
(b) Identify which of the three elements, P, Q, or R, is most likely to be a metal. Give a reason for your answer. [2]
9. State two physical properties that are typical of Group I (alkali) metals. [2]
(i) _________________________________________________________________________
(ii) ________________________________________________________________________
10. Explain why the elements of Group 0 (noble gases) are generally unreactive. [2]
11. Chlorine and bromine are both in Group 7. State one similarity and one difference in their physical properties. [2]
Similarity: __________________________________________________________________
Difference: _________________________________________________________________
12. An element Z has the electronic configuration 2.8.18.7.
(a) In which group of the Periodic Table is element Z found? [1]
(b) Is element Z a metal or a non-metal? Give a reason for your answer. [1]
13. Describe the trend in ionisation energy going down Group 1. Explain your answer in terms of atomic structure. [2]
14. Silicon is described as a metalloid. Explain what is meant by the term metalloid, and state one property that supports this classification. [2]
Section C: Structured Response (Questions 15–20) [15 marks]
15. The table below gives information about four elements from Period 3.
| Element | Melting point (°C) | Electrical conductivity | Oxide nature |
|---|---|---|---|
| A | 98 | Good | Basic |
| B | 650 | Good | Basic |
| C | 1410 | Poor | Amphoteric |
| D | 1610 | Poor | Acidic |
(a) Identify which element (A, B, C, or D) is most likely to be sodium. Give a reason. [2]
(b) Identify which element is most likely to be silicon. Give a reason. [2]
(c) Explain why element D has a very high melting point. [2]
16. The first ionisation energies of the first 20 elements are shown in the graph below (described in words for this quiz):
The graph shows that ionisation energy generally increases across a period but drops significantly at the start of each new period. Notable drops occur from helium (He) to lithium (Li), from neon (Ne) to sodium (Na), and from argon (Ar) to potassium (K).
(a) Explain why the first ionisation energy increases across Period 2 from lithium to neon. [3]
(b) Explain why the first ionisation energy of sodium is much lower than that of neon. [2]
17. A student investigates the reactivity of Group 1 metals with water. The observations are recorded below:
| Metal | Observation with water |
|---|---|
| Lithium | Fizzes slowly on the surface |
| Sodium | Melts into a ball, fizzes rapidly |
| Potassium | Burns with a lilac flame, reacts vigorously |
(a) Describe the trend in reactivity of Group 1 metals with water as you go down the group. [1]
(b) Explain this trend in terms of atomic structure and ionisation energy. [3]
(c) Predict the observation when rubidium is added to water. Give a reason. [2]
18. The table below shows the electronegativity values for some Period 3 elements.
| Element | Na | Mg | Al | Si | P | S | Cl |
|---|---|---|---|---|---|---|---|
| Electronegativity | 0.9 | 1.2 | 1.5 | 1.8 | 2.1 | 2.5 | 3.0 |
(a) State the general trend in electronegativity across Period 3. [1]
(b) Explain this trend in terms of nuclear charge and atomic radius. [3]
(c) Chlorine forms a compound with sodium. Using electronegativity values, explain the type of bonding in sodium chloride. [2]
19. Element M is in Period 3 and Group 2. Element N is in Period 3 and Group 6.
(a) Write the electronic configuration of element M and element N. [2]
M: _________________________________________________________________________
N: _________________________________________________________________________
(b) When M reacts with N, a compound is formed. Write the formula of this compound and explain how you determined it. [3]
(c) State one physical property you would expect this compound to have, and explain your answer in terms of its bonding and structure. [2]
20. A new element, temporarily named Ununennium (symbol Uue), has been synthesised. It has an atomic number of 119.
(a) In which group and period of the Periodic Table would Ununennium be placed? [2]
Group: ______________________________________________________________________
Period: _____________________________________________________________________
(b) Predict one chemical property of Ununennium and explain your prediction based on periodic trends. [3]
(c) Would you expect Ununennium to have a larger or smaller atomic radius than caesium (Cs, atomic number 55)? Explain your answer. [2]
End of Quiz
Answers
Secondary 3 Chemistry Quiz - Periodic Table
Answer Key
Section A: Multiple Choice
1. B
Answer: Elements are arranged in order of increasing atomic (proton) number.
Marking note: Award [1] for B only. The modern Periodic Table is arranged by proton number, not atomic mass (Mendeleev's original arrangement).
2. B
Answer: Group 6, Period 3
Working: Electronic configuration 2.8.6 → 3 electron shells = Period 3; 6 valence electrons = Group 6 (or Group 16 in IUPAC notation).
Marking note: Award [1] for B only. Common error: students may confuse Group 6 with Group 8 (old noble gas group number).
3. B
Answer: They have the same number of valence electrons.
Marking note: Award [1] for B only. Elements in the same group share the same number of outer-shell electrons, which gives them similar chemical properties.
4. C
Answer: Electronegativity increases.
Working: Across Period 3, nuclear charge increases while atomic radius decreases, so the nucleus attracts bonding electrons more strongly. Electronegativity increases from Na to Ar.
Marking note: Award [1] for C only. Atomic radius decreases (not increases), ionisation energy increases (not decreases), and metallic character decreases (not increases) across a period.
5. C
Answer: Krypton
Marking note: Award [1] for C only. Krypton is a Group 0 (Group 18) noble gas. Nitrogen and oxygen are non-metals in Groups 15 and 16; chlorine is a halogen in Group 17.
Section B: Short Answer
6.
Answer: A period is a horizontal row of elements in the Periodic Table. Elements in the same period have the same number of electron shells (energy levels).
Marking note: Award [1] for a clear definition. Accept: "horizontal row" or "elements with the same number of electron shells." Do not accept vague answers like "a line of elements."
7.
(a) Atomic number = 12 [1]
Working: Atomic number = number of protons = 12.
(b) Mass number = 24 [1]
Working: Mass number = protons + neutrons = 12 + 12 = 24.
(c) Element Y is magnesium (Mg). [1]
Use: Used in alloys for aircraft / used in flares / used as a reducing agent in the extraction of titanium / used in antacids. [1]
Marking note: Award [1] for correct identification (magnesium or Mg). Award [1] for any valid use. Common error: students may confuse atomic number and mass number in parts (a) and (b).
8.
(a) [2]
Answer: Moving from P to R across Period 3, the nuclear charge (number of protons) increases. The number of electron shells remains the same, so the increased positive charge pulls the electron shells closer to the nucleus. This results in a decrease in atomic radius.
Marking note: Award [1] for mentioning increasing nuclear charge / more protons. Award [1] for explaining that the electron shells are pulled in / atomic radius decreases as a result.
(b) [2]
Answer: Element P is most likely to be a metal. [1]
Reason: P has the largest atomic radius, which is characteristic of metals. Metals tend to have larger atomic radii and are found on the left side of a period. [1]
Marking note: Award [1] for identifying P. Award [1] for a valid reason linking large atomic radius to metallic character.
9. [2]
Answer (any two):
(i) Soft (can be cut with a knife)
(ii) Low melting point (relative to other metals)
(iii) Good electrical conductor
(iv) Low density (lithium, sodium, and potassium float on water)
(v) Silvery/shiny surface when freshly cut
Marking note: Award [1] each for any two valid physical properties. Do not accept chemical properties (e.g., "reactive with water").
10. [2]
Answer: Noble gases have a full outer shell of electrons (stable electronic configuration). [1] Because their outer electron shell is already complete, they have little or no tendency to gain, lose, or share electrons, making them generally unreactive. [1]
Marking note: Award [1] for stating full/stable outer shell. Award [1] for explaining that this means they do not readily form bonds. Common error: students may say "they have 8 electrons" without noting that helium has only 2.
11. [2]
Similarity (any one): [1]
- Both are non-metals.
- Both exist as diatomic molecules (Cl₂, Br₂).
- Both are coloured (chlorine is greenish-yellow; bromine is reddish-brown).
- Both are poor conductors of electricity.
- Both form ions with a 1− charge (Cl⁻, Br⁻).
Difference (any one): [1]
- Chlorine is a gas at room temperature; bromine is a liquid.
- Chlorine is greenish-yellow; bromine is reddish-brown.
- Chlorine has a lower boiling point than bromine.
- Bromine has a larger atomic radius than chlorine.
Marking note: Award [1] each for a valid similarity and difference. Answers must relate to physical properties, not chemical reactivity.
12.
(a) Group 7 (or Group 17) [1]
Working: Electronic configuration 2.8.18.7 → 7 valence electrons → Group 7.
(b) Non-metal [1]
Reason: Element Z has 7 valence electrons and needs only 1 more electron to complete its outer shell, which is characteristic of non-metals. Non-metals tend to gain electrons to form negative ions. [1]
Marking note: Award [1] for "non-metal." Award [1] for a valid reason (gaining electrons / high electronegativity / 7 valence electrons). Element Z is bromine (Br).
13. [2]
Answer: Ionisation energy decreases going down Group 1. [1]
Explanation: Going down the group, the number of electron shells increases, so the outermost electron is further from the nucleus. The inner electron shells provide more shielding, reducing the effective nuclear attraction on the outermost electron. Less energy is required to remove the outermost electron, so ionisation energy decreases. [1]
Marking note: Award [1] for stating the trend (decreases). Award [1] for a clear explanation involving increased shielding and/or greater distance from the nucleus.
14. [2]
Answer: A metalloid is an element that has properties intermediate between metals and non-metals. [1]
Property: Silicon is a semiconductor — it conducts electricity better than a non-metal but not as well as a metal. (Accept also: silicon is shiny like a metal but brittle like a non-metal; or silicon has an amphoteric oxide.) [1]
Marking note: Award [1] for a correct definition of metalloid. Award [1] for a valid supporting property.
Section C: Structured Response
15.
(a) [2]
Answer: Element A is most likely to be sodium. [1]
Reason: Sodium has a low melting point (98°C), is a good conductor of electricity, and forms a basic oxide — all of which match the data for element A. [1]
Marking note: Award [1] for identifying A. Award [1] for linking at least two properties to sodium.
(b) [2]
Answer: Element C is most likely to be silicon. [1]
Reason: Silicon has a high melting point, is a poor conductor of electricity (semiconductor), and forms an amphoteric oxide (SiO₂), which matches the data for element C. [1]
Marking note: Award [1] for identifying C. Award [1] for linking at least two properties to silicon.
(c) [2]
Answer: Element D has a very high melting point because it has a giant covalent (macromolecular) structure. [1] In a giant covalent structure, all atoms are held together by strong covalent bonds in a three-dimensional network. A large amount of energy is needed to break these strong bonds, resulting in a very high melting point. [1]
Marking note: Award [1] for identifying giant covalent / macromolecular structure. Award [1] for explaining that strong covalent bonds throughout the structure require a lot of energy to break. Element D is likely phosphorus (P₄ is simple molecular, but the data suggests a giant structure — accept reasoning based on the data given).
16.
(a) [3]
Answer: Across Period 2 from Li to Ne, the number of protons (nuclear charge) increases while the number of electron shells remains the same (all in the second shell). [1] The increased nuclear charge attracts the outer electrons more strongly, pulling them closer to the nucleus. [1] This means more energy is required to remove the outermost electron, so the first ionisation energy increases. [1]
Marking note: Award [1] for increasing nuclear charge / more protons. Award [1] for same shell / no additional shielding. Award [1] for concluding that more energy is needed / ionisation energy increases.
(b) [2]
Answer: Sodium is in Period 3, so its outermost electron is in the third electron shell, which is further from the neon's outermost electron (in the second shell). [1] The inner electron shells in sodium also provide more shielding, so the outermost electron experiences less attraction from the nucleus and is easier to remove. Hence, sodium has a much lower first ionisation energy than neon. [1]
Marking note: Award [1] for greater distance from the nucleus / new shell. Award [1] for increased shielding reducing effective nuclear attraction.
17.
(a) [1]
Answer: Reactivity increases going down Group 1.
Marking note: Award [1] for stating that reactivity increases.
(b) [3]
Answer: Going down Group 1, the number of electron shells increases, so the outermost electron is further from the nucleus. [1] The inner shells provide more shielding, reducing the attraction between the nucleus and the outermost electron. [1] This means the ionisation energy decreases, so the outermost electron is more easily lost, making the metal more reactive with water. [1]
Marking note: Award [1] each for: (i) more shells / greater distance, (ii) more shielding, (iii) lower ionisation energy / easier to lose electron / more reactive.
(c) [2]
Answer: Rubidium would react even more vigorously than potassium, possibly with an explosive reaction. [1]
Reason: Rubidium is below potassium in Group 1, so it has more electron shells, greater shielding, and a lower ionisation energy. The outermost electron is lost even more easily, making the reaction more vigorous. [1]
Marking note: Award [1] for predicting a more vigorous/explosive reaction. Award [1] for a valid explanation based on periodic trends.
18.
(a) [1]
Answer: Electronegativity increases across Period 3 from Na to Cl.
Marking note: Award [1] for stating the trend clearly.
(b) [3]
Answer: Across Period 3, the number of protons (nuclear charge) increases. [1] At the same time, the atomic radius decreases because the increased nuclear charge pulls the electron shells closer. [1] The bonding electrons are therefore held more strongly by the nucleus, so the electronegativity increases. [1]
Marking note: Award [1] for increasing nuclear charge. Award [1] for decreasing atomic radius. Award [1] for linking this to stronger attraction for bonding electrons / higher electronegativity.
(c) [2]
Answer: Sodium has an electronegativity of 0.9 and chlorine has an electronegativity of 3.0. The difference is 2.1, which is large. [1] This large difference means that sodium transfers its outer electron to chlorine, forming Na⁺ and Cl⁻ ions that are held together by strong electrostatic forces — ionic bonding. [1]
Marking note: Award [1] for calculating or stating the electronegativity difference. Award [1] for explaining that electron transfer occurs, resulting in ionic bonding. Accept any reasonable threshold (e.g., difference > 1.7) for ionic bonding.
19.
(a) [2]
Answer:
M (Group 2, Period 3 = magnesium): 2.8.2 [1]
N (Group 6, Period 3 = sulfur): 2.8.6 [1]
Marking note: Award [1] each for correct electronic configurations.
(b) [3]
Answer: The formula is MgS. [1]
Explanation: Magnesium (Group 2) loses 2 electrons to form Mg²⁺. Sulfur (Group 6) gains 2 electrons to form S²⁻. [1] One Mg²⁺ ion combines with one S²⁻ ion to form a neutral compound, so the formula is MgS. [1]
Marking note: Award [1] for correct formula. Award [1] for stating Mg loses 2 electrons / forms Mg²⁺. Award [1] for stating S gains 2 electrons / forms S²⁻ and combining in a 1:1 ratio. Common error: students may write Mg₂S or MgS₂.
(c) [2]
Answer: MgS has a high melting point. [1]
Reason: MgS is an ionic compound with a giant ionic lattice structure. Strong electrostatic forces of attraction exist between the Mg²⁺ and S²⁻ ions in all directions. A large amount of energy is required to overcome these strong ionic bonds, so the melting point is high. [1]
Marking note: Award [1] for a valid physical property (high melting point / soluble in water / conducts electricity when molten or in solution). Award [1] for a correct explanation in terms of ionic bonding and structure.
20.
(a) [2]
Group: Group 1 [1]
Period: Period 8 [1]
Working: Atomic number 119 → electronic configuration would end in 8s¹ (one electron in the 8th shell) → Group 1, Period 8.
Marking note: Award [1] each for correct group and period.
(b) [3]
Answer: Ununennium would be a highly reactive metal that reacts vigorously with water to produce hydrogen gas and a strong alkali (UueOH). [1]
Explanation: Ununennium is in Group 1, so it has one valence electron. Based on the trend down Group 1, it would have a very large atomic radius, very low ionisation energy, and very low electronegativity. [1] The outermost electron would be extremely easy to lose, making it the most reactive alkali metal. It would react with water even more violently than caesium or francium. [1]
Marking note: Award [1] for predicting a valid chemical property (reacts with water / forms a +1 ion / strong reducing agent / forms a basic oxide). Award [1] for referencing Group 1 trends. Award [1] for explaining based on low ionisation energy / large atomic radius / easy electron loss.
(c) [2]
Answer: Ununennium would have a larger atomic radius than caesium. [1]
Reason: Ununennium is below caesium in Group 1, so it has more electron shells. Although the nuclear charge is greater, the increased number of shells and increased shielding mean that the outermost electron is much further from the nucleus, resulting in a larger atomic radius. [1]
Marking note: Award [1] for "larger." Award [1] for a valid explanation involving more electron shells and/or increased shielding.
End of Answer Key