Note that there are two valence electrons of the SP type plus one 2PY and one 2PZ unhybridized types. The carbon-carbon triple bond is not free to rotate, the bond angles are 180 degrees and the shape of the molecule is linear. A molecule containing four carbons and one triple bond is named butyne. Some examples and properties of unsaturated hydrocarbons. The last molecule is the visual pigment of ALL visual systems in the Animal Kingdom.
Plants produce isoprene, a major haze ingredient, as a strategy for coping with heat.
They are also ingredients in photochemical smog, where along with hydrocarbons from automobiles and trucks, they combine with nitrogen oxides to generate low-level ozone, an irritant to lungs and to plants themselves. In urban areas, like Atlanta, isoprene produced by plants is the major daily hydrocarbon emission source. Thus it will be difficult to reduce hydrocarbon emissions, and perhaps the major target should be nitrogen oxides. Review the concept of nucleophile and electrophile, and the addition type of reaction.