Video Transcript
Why do no values exist on the Pauling scale of electronegativity for argon, neon, and helium? (A) These noble gases are synthetic elements and do not exist in quantities large enough to be measured. (B) These noble gases do not form bonds; therefore, no bond dissociation energy data is available. (C) These noble gases have too great an electron density (D). These noble gases require too much energy to be ionized. Or (E) these noble gases exist as electrically neutral atoms.
This is a question about electronegativity. Electronegativity is defined as the tendency of an atom to attract a bonding pair of electrons. To compare the electronegativity of different elements, we use the Pauling scale. Values on the Pauling scale range from francium at 0.7 all the way up to fluorine at 3.98. A clue to the correct answer exists in the definition. We’re specifically talking about electrons involved in bonds.
While the precise process is too intricate to be included in this video, we can say that when he came up with this scale, American chemist Linus Pauling used bond association data to compare the electronegativity of elements. However, noble gases like neon have full outer electron shells and therefore do not form bonds with other atoms to make compounds. Because they do not form bonds, Pauling was unable to include them in his Pauling scale. This reason corresponds with answer choice (B), the correct answer.
To be thorough, let’s also review the remaining answer choices. Answer choice (A) talks about synthetic elements, the elements between number 104 and 118 on the periodic table. In other words, from rutherfordium to oganesson in the seventh period fit this description. They are created in highly specialized conditions in a laboratory and exist in tiny amounts for a fraction of a second. This is a reason why those elements aren’t included on the Pauling scale, but that reasoning does not apply to noble gases. We can eliminate choice (D) as well. While it is true that noble gases require a lot of energy to be ionized, that fact is more relevant to a discussion of ionization energy than electronegativity.
We can eliminate choice (E) from consideration as well. While noble gases do exist as electrically neutral atoms, plenty of other elements that exist as electrically neutral atoms are included in the Pauling scale. Lastly, we can eliminate choice (C) as these noble gases do not have particularly large electron densities. Again, the key piece of information is that these noble gases do not form bonds.
So, why do no values exist on the Pauling scale of electronegativity for argon, neon, and helium? That’s choice (B): these noble gases do not form bonds; therefore, no bond dissociation energy data is available.
