Lewis Structure and Hybridization of HSCN (thiocyanic acid, hydrogen thiocyanide)

HSCN is the corresponding acid of SCN-, which is the thiocyanide ion. All four of these atoms are non-metals, the bonds between them will be covalent, and it will make a molecular compound.

Carbon brings four valence electrons with it, and so needs four more to complete its valence shell. Nitrogen brings five valence electrons, and so it needs three to completed its octet. Carbon and nitrogen share three electrons each (with each other) and a triple bond forms between them.

Meanwhile, carbon needs one more electron and sulfur can provide it. This also gives sulfur a seventh electron, and it gets its eighth from hydrogen.

HSCN has a single bond between H and S, a single bond between S and C, and a triple bond between C and N.

What is the hybridization of C in HSCN?

Carbon is triple-bonded to nitrogen; this requires two pi bonds and that means it requires two leftover p orbitals after hybridization; so the C is “sp” hybridized.

What is the hybridization of N in HSCN?

N is also triple bonded, so it is “sp” hybridized as well. The sigma bond (first bond between the two is sigma) and the lone pair are where the “hybridized sp orbitals” are used here.

What is the hybridization of S in HSCN?

The sulfur atom has NO double or triple bonds. It has two single bonds (both sigma) and two lone pairs. This means is does not need any leftover p orbitals (which would need to stay unhybridized) and so sulfur is “sp3” hybridized here.

What is the VSEPR shape of HSCN?

The carbon atom is only bonded to two other atoms and has no lone pairs; this gives it AX2 geometry, and so there is a linear arrangement around the carbon atom.

The sulfur, on the other hand, has two sigma bonds (single bonds on either side) AND two lone pairs. This gives it Ax2E2 geometry and so it is V-Shaped/Non-linear/Bent.

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