Download App

Elements of Groups 16, 17 and 18 — Chemistry STD 12 Science — Question

Maharashtra BoardEnglish MediumSTD 12 ScienceChemistryElements of Groups 16, 17 and 184 Marks
Question
Explain the general structures of hydrides of group $16$ elements.
Give reason : Bond angle decreases from $H_2O$ to $H_2S.$
✓

Answer

  • Group $16$ elements form hydrides of the type $H _2 M$ where $M = O, S, Se, Te$ and $Po.$
  • All these hydrides are formed by $sp ^3$ hybridisation of the central atom and have angular shape.
  • All hydrides have similar structure but differ in $H-M-H$ bond angle. This bond angle decreases from $H _2 O$ to $H _2 Te$.
  • All these hydrides have two $M-H$ bond pairs and two lone pairs of electrons.
  • Due to repulsion between lone pairs$-$lone pairs and lone pairs$-$bond pairs, and bond pairs$-$bond pairs the bond angle is reduced from regular $109^{\circ} 28^{\prime}$.
  • On moving down the group, atomic size increases, electronegativity decreases, electron density decreases.
  • Since among group $16$ elements, oxygen has the highest electronegativity, lowest atomic size and hence the highest electron density, the repulsion between electron pairs is maximum in $H _2 O$, hence $H-O-H$ bond angle is maximum.
  • The electron pair repulsion decreases down the group, hence bond angle also decreases down the group.
    Hydrides $H _2 O$ $H _2 S$ $H _2 Se$ $H _2 Te$
    $H-M-H$ angle $104^{\circ}$ $90^{\circ}$

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 "Answer the following in detail." from Elements of Groups 16, 17 and 18→Elements of Groups 16, 17 and 18 — all question types→Chemistry STD 12 Science question papers→Maharashtra Board STD 12 Science question papers→Maharashtra Board question paper generator→

Similar questions

Identify conjugate acid-base pairs in the following:
(a) $NH _4^{+}+ OH ^{-} \rightleftharpoons NH _3+ H _2 O$
(b) $HCO _3^{-}+ H _2 O \rightleftharpoons H _3 O ^{+}+ CO _3^{2-}$
(c) $NH _4^{+}+ H _2 O \rightleftharpoons H _3 O ^{+}+ NH _3$
(d) $HNO _3+ H _2 O \rightleftharpoons H _3 O ^{+}+ NO _3^{-}$
(e) $HSO _4^{-}+ H _2 O \rightleftharpoons H _3 O ^{+}+ SO _4^{--}$
(f) $HCl + H _2 O \rightleftharpoons H _3 O ^{+}+ Cl ^{-}$
→
Draw structure of chlorous acid.
→
How are the voltaic cells classified ?
→
What are oxides? Write different types of oxides with one example each.
→
What are the differences between cast iron, wrought iron and steel?
→
Define and explain the following electrical units : (1) Coulomb (2) Ampere (3) Volt (4) Joule (5) Ohm.
→
Obtain the expression for dissociation constant in terms of $∧_c$​​​​​​​ and $∧_0​​​​​​​$​​​​​​​ using Ostwald’s dilution law.
→
Give the physical states of the following molecules:
$BrCl , IBr , IF _5, BrF _5, ClF _3, IF _7$
→
Write reactions for the action of the following reagents on p-chlorobenzaldehyde.
Phenyl hydrazine
→
Explain the reactivity of group 16 elements towards halogens.
→