Download App

Classification of Elements and Periodicity in Properties — Chemistry STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 ScienceChemistryClassification of Elements and Periodicity in Properties5 Marks
Question
Among the second period elements the actual ionization enthalpies are in the order $Li < B < Be < C < O < N < F < Ne$. Explain why,
  1. Be has higher $\Delta_{\text{t}}\text{H}$ than B
  2. O has lower $\Delta_{\text{t}}\text{H}$ than N and F?
✓

Answer

  1. During ionization process, the electron that can be expelled from Be (beryllium) – atom is 2s – electron, but the electron that can be expelled from boron is 2p – electron.The attractive force between a 2s – electron and nucleus is higher than between a 2s – electron and nucleus.Thus, the energy required to expel 2s –electron is higher than the energy required to expel 2p –electron.Thus, $\Delta_\text{i}\text{H}$ for Be is higher than $\Delta_\text{i}\text{H}$ than B
  2. In nitrogen, there are three 2p-electrons and all of these 3 occupy 3 distinct atomic orbital. While in oxygen 2 out of 4, 2p – electrons occupy same 2p-orbital, so the repulsion between the electrons in the oxygen atom increases.Thus, the energy required to expel $2^{nd}$ 2p –electron in oxygen atom is higher than the energy required to expel $4^{th}$ 2p –electron in nitrogen atom.Thus, $\Delta_\text{i}\text{H}$ for O is lower than $\Delta_\text{i}\text{H}$ of N.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "5 Marks Questions" from Classification of Elements and Periodicity in Properties→Classification of Elements and Periodicity in Properties — all question types→Chemistry STD 11 Science question papers→Gujarat Board STD 11 Science question papers→Gujarat Board question paper generator→

Similar questions

  1. A cylinder of gas supplied by a company is assumed to contain 14kg of butane. If a normal family requires 20000kJ of energy per day for cooking, how long will the cylinder last?
  2. If the air supplied to the burner is insufficient, a portion of gas escapes without combustion. Assuming that 25% of the gas is wasted due to this inefficiency, how long will the cylinder last (Heat of combustion of butane $= 2658kJ/ mol.)?$
→
What is overlapping of atomic orbitals? How many types are there? Discuss in detail.
→
Calculate the energy required for the process,
$\text{He}^+(\text{g})\rightarrow\text{He}^{2+}\text{(g)}+\text{e}^-$
The ionization energy for the H atom in the ground state is $2.18 \times 10^{-18} \mathrm{~J}$ atom $^{-1}$
→
Draw the structures of $\mathrm{BCl}_3$. $\mathrm{NH}_3$ and $\mathrm{AlCl}_3$ (dimer).
→
i. An athlete is given 100 g of glucose of energy equivalent to 1560 kJ . He utilises $50 \%$ of this gained energy in the event. In order to avoid storage of energy in the body, calculate the weight of water that would need to perspire. The enthalpy of vaporisation of water is $44 kJ mol ^{-1}$.
ii. Compound with carbon-carbon double bond, such as ethylene, $C _2 H _4$, add hydrogen in a reaction called hydrogenation, $C _2 H _4(g)+ H _2(g) \rightarrow C _2 H _6(g)$
Calculate enthalpy change for the reaction, using the following combustion data,

$\text{C}_2\text{H}_4(\text{g})+3\text{O}_2(\text{g})\overrightarrow{\ \ \ \ \ }\ 2\text{CO}_2(\text{g})+2\text{H}_2\text{O(l)};$ $\Delta_\text{c}\text{H}^\circ=-1401\text{kJ mol}^{-1}\dots(\text{i})$

$\text{C}_2\text{H}_6(\text{g})+\frac{7}{2}\text{O}_2(\text{g})\overrightarrow{ \ \ \ \ \ \ \ }\ 2\text{CO}_2(\text{g})+3\text{H}_2\text{O(l)}$ $\Delta_\text{c}\text{H}^\circ=-1550\text{kJ mol}^{-1}\dots(\text{ii})$

$\text{H}_2(\text{g})+\frac{1}{2}\text{O}_2(\text{g})\overrightarrow{ \ \ \ \ }\ \text{H}_2\text{O(l)};$ $\Delta_\text{c}\text{H}^\circ=-286.0\text{kJ mol}^{-1}\dots(\text{iii})$
→
1. a. Define the following terms:
i. Enantiomers
ii. Racemic mixture
b. Why is chlorobenzene resistant to nucleophilic substitution reaction?
2. What is the general molecular formula of saturated monohydric alcohols?
→
$2.9g$ of a gas at $95^\circ C$ occupied the same volume as $0.184g$ of dihydrogen at $17^\circ C$, at the same pressure. What is the molar mass of the gas?
→
A compound on analysis found to contain following percentage composition:
$Na = 43.4\%, C = 11.4\%$ and $O = 45.3\%$. Determine the empirical and molecular formulae.
Given: the relative molecular mass of the compound is $106$.
→
Compare the geometry and bond angle of those molecules of type AB₂, AB3, AB4 and AB5 in which the lone (1.p) electron pair is not present on the central atom.
→
Discuss the concept of hybridisation. What are its different types in a carbon atom.
→