The Periodic Table
11 Grade 10 General Science questions on The Periodic Table, with worked marking schemes. 11 questions are available on this topic in full.
Question 1
1 markWhich of the following compounds has its chemical formula correctly written?
A. CaNO₃ for calcium nitrate
B. MgCl for magnesium chloride
C. Na₂O for sodium oxide
D. KSO₄ for potassium sulphate
(1 mark)
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5 marksCalcium (atomic number 20) reacts with sulphur (atomic number 16) to form an ionic compound.
(a) Using dot (.) and cross (x) diagrams, show how a calcium atom forms a calcium ion. (2 marks)
(b) Using dot (.) and cross (x) diagrams, show how a sulphur atom forms a sulphide ion. (2 marks)
(c) Write the chemical formula of the compound formed. (1 mark)
(5 marks)
Marking scheme
(a) - Calcium atom drawn with electron arrangement 2.8.8.2 (1 mark). - Calcium ion drawn with arrangement 2.8.8, showing loss of the two outer electrons and the charge 2+ (Ca²⁺) (1 mark). (b) - Sulphur atom drawn with electron arrangement 2.8.6 (1 mark). - Sulphide ion drawn with arrangement 2.8.8, the two gained electrons shown with a different symbol (dots or crosses) from sulphur's own electrons, and the charge 2- (S²⁻) (1 mark). (c) CaS (1 mark). (Accept diagrams showing only the outer energy level if the full arrangement is stated. Charge must be shown to earn the ion mark.)
Question 3
1 markThe modern periodic law states that the physical and chemical properties of elements are a periodic function of their
A. numbers of neutrons
B. atomic numbers
C. densities and melting points
D. atomic masses
(1 mark)
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Create a free account to see itQuestion 4
1 markAn atom of element X has a mass number of 31 and contains 16 neutrons. Which of the following is the electron arrangement of an atom of X?
A. 2.8.4.1
B. 2.5.8
C. 2.8.3.2
D. 2.8.5
(1 mark)
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4 marksCalculate the oxidation number of:
(a) sulphur in sulphuric acid, H₂SO₄ (2 marks)
(b) nitrogen in the ammonium ion, NH₄⁺ (2 marks) (Take the oxidation number of hydrogen as +1 and that of oxygen as -2.)
(4 marks)
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5 marksIn a Grade 10 class activity, learners were given six cards, each showing the electron arrangement of an atom of an element. Card 1: 2.8.7 Card 2: 2.2 Card 3: 2.1 Card 4: 2.7 Card 5: 2.8.1 Card 6: 2.8.2
(a) Sort the cards into three pairs, each pair representing elements in the same group of the periodic table. (3 marks)
(b) Explain why elements in the same group show similar chemical properties. (2 marks)
(5 marks)
Marking scheme
(a) 1 mark for each correct pair (3 marks): - Card 3 and Card 5 (one outer electron, Group I) - Card 2 and Card 6 (two outer electrons, Group II) - Card 1 and Card 4 (seven outer electrons, Group VII) (b) - Elements in the same group have the same number of electrons in their outermost energy level (1 mark). - Chemical reactions involve the outer electrons, which are lost, gained or shared in the same way, so the elements react in a similar manner (1 mark).
Question 7
5 marksThe electron arrangements of three elements, X, Y and Z, are given below. The letters are not the actual symbols of the elements. X: 2.8.7 Y: 2.8.1 Z: 2.8.2
(a) What is meant by electron affinity? (1 mark)
(b) Explain, in terms of stability, the type of ion formed by X and by Y. (2 marks)
(c) Explain why Y forms its ion more readily than Z. (2 marks)
(5 marks)
Marking scheme
(a) The energy released when an electron is added to a gaseous atom to form a negatively charged ion (1 mark). (b) - X gains one electron to attain the stable octet arrangement 2.8.8, forming a negative ion, X⁻ (1 mark). - Y loses its single outer electron to attain the stable arrangement 2.8, forming a positive ion, Y⁺ (1 mark). (c) Any two, 1 mark each (2 marks): - Y needs to lose only one electron while Z must lose two electrons to become stable. - Removing one electron requires less energy than removing two, so Y ionises more easily. - Z has one more proton than Y, so its outer electrons are more strongly attracted by the nucleus and are harder to remove. - The atom of Y is larger than that of Z, so its outer electron is further from the nucleus and is held less strongly.
Question 8
1 markThe noble gases rarely take part in chemical reactions. Which of the following statements best explains this?
A. Their atoms have equal numbers of protons and neutrons
B. Their outer energy level holds a stable, full set of electrons
C. Their atoms readily lose outer electrons to form stable cations
D. Their atoms exist as diatomic molecules sharing electron pairs
(1 mark)
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4 marksUse the valencies of the elements and radicals involved to write the chemical formula of each of the following compounds.
(a) Aluminium sulphate (1 mark)
(b) Ammonium carbonate (1 mark)
(c) Calcium phosphate (1 mark)
(d) Potassium hydrogen carbonate (1 mark)
(4 marks)
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4 marksWrite a balanced chemical equation for each of the following reactions.
(a) Calcium carbonate reacts with dilute hydrochloric acid to form calcium chloride, water and carbon dioxide. (2 marks)
(b) Nitrogen combines with hydrogen to form ammonia. (2 marks)
(4 marks)
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1 markElement Y has the electron arrangement 2.8.2. In which group and period of the periodic table is Y found?
A. Group III, period 3
B. Group II, period 3
C. Group II, period 2
D. Group III, period 2
(1 mark)
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