What does the block of an element tell you?

The type of sub-shell (s, p, d or f) that contains the highest-energy electron.

Which region is the p block?

The six columns on the right-hand side of the table (Groups 3 to 0, or 13 to 18).

Which elements are in the f block?

The lanthanides and actinides, the two rows set apart at the bottom.

What does proton number determine about an atom's electrons?

The number of electrons in a neutral atom, and so its electron configuration.

Which block is sodium (11) in? Why?

s block: its highest-energy electron is in the 3s sub-shell (1s²2s²2p⁶3s¹).

Which block is chlorine (17) in? Why?

p block: its highest-energy electron is in a 3p sub-shell.

Which block is iron (26) in? Why?

d block: the last sub-shell to be filled is 3d.

How many elements are in each row of the d block?

10, because a d sub-shell holds 10 electrons.

How many elements are in each row of the p block?

6, because a p sub-shell holds 6 electrons.

How many elements fill the f block in a row?

14, because an f sub-shell holds 14 electrons.

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

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How is an element classified as s, p, d or f block?

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How is an element classified as s, p, d or f block?: By its position in the Periodic Table, which is determined by its proton number.
What does the block of an element tell you?: The type of sub-shell (s, p, d or f) that contains the highest-energy electron.
Which groups make up the s block?: Groups 1 and 2.
Which region is the p block?: The six columns on the right-hand side of the table (Groups 3 to 0, or 13 to 18).
Which block contains the transition metals?: The d block.
Which elements are in the f block?: The lanthanides and actinides, the two rows set apart at the bottom.
What does proton number determine about an atom's electrons?: The number of electrons in a neutral atom, and so its electron configuration.
Which block is sodium (11) in? Why?: s block: its highest-energy electron is in the 3s sub-shell (1s²2s²2p⁶3s¹).
Which block is chlorine (17) in? Why?: p block: its highest-energy electron is in a 3p sub-shell.
Which block is iron (26) in? Why?: d block: the last sub-shell to be filled is 3d.
How many elements are in each row of the d block?: 10, because a d sub-shell holds 10 electrons.
How many elements are in each row of the p block?: 6, because a p sub-shell holds 6 electrons.
How many elements fill the f block in a row?: 14, because an f sub-shell holds 14 electrons.

Exam questions on Classification of elements in the periodic table

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).
Explain why the block that an element belongs to is determined by its proton number.2 marks
The electron configurations of four unnamed elements are: W 1s²2s²2p⁶3s²; X 1s²2s²2p⁶3s²3p⁶3d⁵4s²; Y 1s²2s²2p⁶3s²3p⁶3d¹⁰4s²4p⁵; Z [Xe]4f⁷6s².
Deduce the block of elements Y and Z. Give a reason for each answer.2 marks
A data card for a periodic table quiz gives three elements by proton number only: 38, 22 and 34.
Use the Periodic Table to identify the block (s, p, d or f) in which each of these three elements is found.3 marks

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Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).