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Class 11 Classification of Elements and Periodicity in Properties worksheet
CBSE Chemistry. Period, group and block, trends in radius, ionisation and electron gain enthalpy, IUPAC names. Every sheet has 20 questions in three sections and an answer key, and the numbers change every time.
Sample questions
Real questions from this chapter, as the app sets them. Tap Answer to see the answer and working.
Section A · multiple choice
- 1.
The modern periodic law states that the properties of elements are a periodic function of their:
- densities
- numbers of neutrons
- atomic masses
- atomic numbers
Answer
(d) atomic numbers
Moseley showed atomic number is the basis
- 2.
The element with atomic number 15 lies in:
- period 3, group 15
- period 4, group 15
- period 2, group 15
- period 3, group 5
Answer
(a) period 3, group 15
1s² 2s² 2p⁶ 3s² 3p³: p-block
- 3.
Which shows the correct order of increasing electronegativity?
- Na < Li < K
- K < Li < Na
- K < Na < Li
- Li < Na < K
Answer
(c) K < Na < Li
K 0.8, Na 0.9, Li 1.0
Section B · short answer
- 4.
Why is the first ionisation enthalpy of boron lower than that of beryllium?
Answer
Boron’s outer electron is in 2p, which is higher in energy and shielded by the 2s electrons, so it is removed more easily than a 2s electron of beryllium.
- 5.
Write the electronic configuration of the element with atomic number 35, and give its period, group and block.
Answer
[Ar] 3d¹⁰ 4s² 4p⁵; period 4, group 17 (p-block)
period = highest n; block = subshell of the last electron; group from the outer electrons
Section C · long answer
- 6.
Explain how the electronic configuration of an element decides its period, group and block, with one example from each block.
Answer
Period = the highest principal quantum number n. Block = the subshell receiving the last electron. Group: s-block = number of ns electrons; p-block = 10 + (ns + np electrons); d-block = ns + (n − 1)d electrons. Examples: Na 3s¹: period 3, group 1, s-block. Cl 3s² 3p⁵: period 3, group 17, p-block. Fe 3d⁶ 4s²: period 4, group 8, d-block.
Fresh sheets for your child
In the app, every Classification of Elements and Periodicity in Properties sheet is new: the app remembers the questions your child has already had and leaves them out. Print the sheet as a PDF, or use notebook mode and write the answers in a notebook.
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