Classification of elements in the periodic tableAQA A-Level Chemistry: Subtopic test

1. 1
   A student classifies elements using only their proton numbers and a periodic table. The elements are sodium (11), iron (26), arsenic (33) and terbium (65).

   (a)

   Which of these elements is in the d block?

   [1 mark]

   • ASodium
   • BIron
   • CArsenic
   • DTerbium

   (b)

   In which block of the Periodic Table is arsenic found?

   [1 mark]

   • As block
   • Bd block
   • Cf block
   • Dp block

   (c)

   Explain why the block that an element belongs to is determined by its proton number.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   The electron configurations of four unnamed elements are: W 1s²2s²2p⁶3s²; X 1s²2s²2p⁶3s²3p⁶3d⁵4s²; Y 1s²2s²2p⁶3s²3p⁶3d¹⁰4s²4p⁵; Z [Xe]4f⁷6s².

   (a)

   Which of the elements W, X, Y and Z is in the s block?

   [1 mark]

   • AW
   • BX
   • CY
   • DZ

   (b)

   Element X is in the d block. Which statement gives the correct reason?

   [1 mark]

   • AIts outer electrons are in the 4s sub-shell
   • BIt has seven electrons in its outer shell
   • CThe highest-energy electrons are in the 3d sub-shell
   • DIts proton number is greater than 20

   (c)

   Deduce the block of elements Y and Z. Give a reason for each answer.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A data card for a periodic table quiz gives three elements by proton number only: 38, 22 and 34.

   (a)

   Use the Periodic Table to identify the block (s, p, d or f) in which each of these three elements is found.

   [3 marks]

   (b)

   Write the full electron configuration of the element with proton number 34. Explain how this configuration shows which block it is in, and state how many electrons it has in its 4p sub-shell.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   The Periodic Table is arranged in order of proton number and divided into s, p, d and f blocks. Period 4 runs from potassium (proton number 19) to krypton (proton number 36), and the 4s sub-shell fills before the 3d sub-shell.

   (a)

   Describe and explain how the elements from potassium to krypton are classified into blocks, and how the proton number is used to do this.

   [6 marks]

   (b)

   Explain why the s, p, d and f blocks contain 2, 6, 10 and 14 elements respectively across a row. Use the sub-shells to deduce the proton numbers of the first and last d-block elements in Period 4 and the proton number of the last p-block element in Period 4.

   [6 marks]

   Total for question 4: 12 marks

End of questions