Does this lewis structure correctly shows a triple covalent bond?

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gsenviro | College Teacher | (Level 1) Educator Emeritus

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A triple covalent bond is formed between atoms sharing 3 electrons each. In this case, we have to figure out if the given Lewis dot structure is correct for triple covalent bonds between two carbon atoms. Carbon has an atomic number of 6 and an electronic configuration of `1s^2, 2s^2, 2p2`

which means it has 4 valence electrons. These four electrons can be shared to reach a filly filled electronic configuration or noble gas configuration.

A Lewis dot structure for a triple covalent bond will show 3 electrons (represented by dots) being shared by each atom, which is the case in this question. However, since carbon has only 4 valence electrons, it will have only one valence electron left after sharing 3 valence electrons with another carbon atom. Hence there should be only 1 unshared dot. Here we are given 2 dots each, depicting 5 valence electrons, which is wrong.

Hence the given Lewis dot structure shows a triple covalent bond, but not of carbon, as carbon has only 4 valence electrons as compared to the 5 shown in the image.

Hope this helps.