Show the formation of the following molecules. Carbon dioxide, Hydrogen sulfide. Class 9

Show the formation of the following molecules. Carbon dioxide, Hydrogen sulfide. Class 9

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Question 1.

Show the formation of the following molecules:

(i) Carbon dioxide (CO₂)

(ii) Hydrogen sulfide (H₂S)

(iii) Ammonia (NH₃)

Answer:

(i) Carbon dioxide (CO₂): Carbon (atomic number 6) has 4 valence electrons and needs 4 more to complete its octet. Oxygen (atomic number 8) has 6 valence electrons and needs 2 more. Each oxygen atom shares 2 electrons with the carbon atom. Carbon shares 2 electrons with each of the two oxygen atoms. Thus, two double bonds are formed: O=C=O. Carbon dioxide has two double covalent bonds.

(ii) Hydrogen sulfide (H₂S): Sulfur (atomic number 16) has 6 valence electrons and needs 2 more electrons to complete its octet. Hydrogen needs 1 electron to complete its duplet. Sulfur shares one electron each with two hydrogen atoms. Each hydrogen atom shares one electron with sulfur. Two single bonds are formed: H-S-H (each bond is a single covalent bond).

(iii) Ammonia (NH₃): Nitrogen (atomic number 7) has 5 valence electrons and needs 3 more electrons to complete its octet. Hydrogen needs 1 electron to complete its duplet. Nitrogen shares one electron each with three hydrogen atoms. Each hydrogen atom shares one electron with nitrogen.

Three single bonds are formed: H-N-H with one H below (or depicted as N at centre bonded to three H atoms). Ammonia has three single covalent bonds and one lone pair on nitrogen.