Question

Draw the Lewis structures for the following molecules and ions: \(H_2S\), \(SiCl_4\), \(BeF_2\), \(CO_3^{2-}\) , \(HCOOH\)

Answer 1

Lewis structures (description for drawing):

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(a) H₂S:

Sulphur is the central atom with two hydrogen atoms bonded to it by single bonds.

Sulphur has two lone pairs of electrons.

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(b) SiCl₄:

Silicon is the central atom bonded to four chlorine atoms by single covalent bonds.

Each chlorine atom has three lone pairs, while silicon has no lone pair.

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(c) BeF₂:

Beryllium is the central atom bonded to two fluorine atoms by single bonds.

Each fluorine atom has three lone pairs.

Beryllium has an incomplete octet (only four electrons around it).

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(d) CO₃²⁻ (Carbonate ion):

Carbon is the central atom bonded to three oxygen atoms.

One C–O bond is a double bond and the other two are single bonds.

The negative charges are present on the singly bonded oxygen atoms.

The structure shows resonance, as the position of the double bond can change among the three oxygen atoms.

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(e) HCOOH (Formic acid):

Carbon is the central atom.

One oxygen is double bonded to carbon (C=O), and the other oxygen is single bonded to carbon and hydrogen (–OH).

Each oxygen atom has two lone pairs.

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Final Note:

The Lewis structures of all the above molecules and ions can be drawn using the descriptions provided, showing correct bonding and lone pairs.