Science (086) — AI-generated practice question

Carbon has 4 electrons in its outermost shell. To form C⁴⁺, it would need to lose 4 electrons, requiring a very large amount of energy. To form C⁴⁻, it would need to gain 4 electrons, which would be difficult for the nucleus to hold. Both processes are energetically unfavourable.

Instead, carbon achieves noble gas configuration (8 electrons in outermost shell) by sharing its 4 valence electrons with other atoms, forming 4 covalent bonds. Carbon's small size allows its nucleus to hold shared electron pairs strongly, making these bonds stable. For example, in methane (CH₄), carbon shares one electron each with four hydrogen atoms.

Source: Chapter 4, Section 4.2 — Versatile Nature of Carbon

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• Examiners expect two parts: (1) why ionic bonding fails for carbon, and (2) how covalent bonding solves it.
• Mention both C⁴⁺ and C⁴⁻ separately — each is worth a point.
• Naming covalent bonds / sharing of electrons and giving methane as an example shows application.
• The phrase "small size → nucleus holds shared pairs strongly" is directly from the textbook and scores well.