Why does PCl3 fume in the presence of moisture?
In the presence of moisture, PCl3 undergoes hydrolysis to release fumes of HCl gas.
PCl3 + 3H2O → H3PO3 + 3HCl
The reaction mechanism is shown as,

In the presence of moisture, PCl3 undergoes hydrolysis to release fumes of HCl gas.
PCl3 + 3H2O → H3PO3 + 3HCl
The reaction mechanism is shown as,

The discovery of isomerism marked the advent of structural chemistry, where it became significantly important to establish structural formulas, welcome the abundance of structurally diverse compounds, classify them, and study their individual properties and impacts.
A carbocation is a positively charged, electron-deficient carbon atom that acts as a reactive intermediate in many organic reactions.

If a two-electron covalent bond breaks symmetrically, each of the two atoms receive one electron; it is a homolytic bond cleavage.
A homolytic cleavage is shown using a fish-hook arrow, which implies one-electron movement.
- The unit cells that makes up the entire crystalline solid has a fixed value for the length of the edges and the angle between the edges.

- Therefore, the heat energy required to melt a crystalline solid would have a fixed value.
Metallic solid consists of several metal atoms of the same kind bonded together closely. Due to their large size, metals easily lose their outermost valence electrons. The delocalized valence electron drifts and is now available for the other nuclei of metal atoms. Several delocalized electrons are comparable to a sea of electrons.
A metal atom is large, so the nucleus cannot attract and hold its outermost electrons. The metal loses those electrons and becomes positively charged kernels. The electrons then flow in the solid structure passing between these positive kernels.
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A carbocation is a positively charged, electron-deficient carbon ion that acts as a reactive intermediate in many organic reactions.
The central carbon in a carbocation has only 6 valence electrons instead of the preferred 8 by covalent bonding. As a result, it has only three covalent bonds and, therefore, trivalent.
Following the footsteps of Gilbert N. Lewis in understanding the nature of the covalent bond, Linus N. Pauling stumbled upon an interesting observation. Pauling noticed that the nature of the chemical bond could be explained using a scale or continuum.