Vidaara.orgClass 11 · Chemistry
CodeVID-C11-03-T1-01
Development & Modern Periodic Law — Assignment
Name: ____________________
Roll No.: __________
Date: ____________
General Instructions
- All questions are compulsory.
- Section A carries 1 mark each, Section B 2 marks, Section C 3 marks and Section D 5 marks.
- Show full working for Sections B, C and D; only final answers are provided.
Section A — Multiple Choice Questions
5 × 1 = 5 marks
1.
The Periodic Law as stated by Mendeleev was based on:
- A.atomic number
- B.atomic mass
- C.valence electrons
- D.ionisation energy
2.
The number of groups in the long form of the periodic table is:
- A.8
- B.16
- C.18
- D.32
3.
Elements of the f-block are called:
- A.transition elements
- B.inner-transition elements
- C.representative elements
- D.noble gases
4.
Newlands' classification was called the Law of:
- A.Triads
- B.Octaves
- C.Periods
- D.Mass
5.
The outer configuration $ns^2np^6$ is characteristic of:
- A.alkali metals
- B.halogens
- C.noble gases
- D.transition metals
Section B — Short Answer (2 marks)
3 × 2 = 6 marks
6.
State the Modern Periodic Law.
7.
Why does a period start with an alkali metal and (mostly) end with a noble gas?
8.
Give the IUPAC name and symbol for $Z = 105$.
Section C — Long Answer (3 marks)
2 × 3 = 6 marks
9.
Explain two merits and one limitation of Mendeleev's periodic table.
10.
Classify the element $Z = 35$ into its period, group and block with reasoning.
Section D — Detailed Answer (5 marks)
1 × 5 = 5 marks
11.
Describe how the long form of the periodic table is divided into s, p, d and f blocks. Give the general valence configuration and one example element from each block.
Answer Key
Section A — Multiple Choice Questions
- (B) atomic mass
- (C) 18
- (B) inner-transition elements
- (B) Octaves
- (C) noble gases
Section B — Short Answer (2 marks)
- The physical and chemical properties of elements are a periodic function of their atomic numbers.
- A new period begins when a new principal shell starts filling ($ns^1$, alkali metal) and ends when that shell's $s$ and $p$ subshells are full ($ns^2np^6$, noble gas).
- Unnilpentium, symbol Unp.
Section C — Long Answer (3 marks)
- Merits: it predicted undiscovered elements (eka-elements) and corrected several doubtful atomic masses. Limitation: isotopes had no place and the H position was anomalous; some heavier elements (Te, I) had to be placed against the mass order.
- Configuration $[\text{Ar}]3d^{10}4s^24p^5$; last electron in $4p$ so p-block; $n=4$ so period 4; group $= 10 + 7 = 17$ (a halogen, bromine).
Section D — Detailed Answer (5 marks)
- s-block (Gp 1-2): $ns^{1-2}$, e.g. Na. p-block (Gp 13-18): $ns^2np^{1-6}$, e.g. Cl. d-block (Gp 3-12): $(n-1)d^{1-10}ns^{0-2}$, e.g. Fe. f-block: $(n-2)f^{1-14}$, e.g. Ce. The block is decided by the subshell receiving the last electron.
Generated by Vidaara.org · Assignment VID-C11-03-T1-01 · vidaara.org