A hydrogen atom can form a covalent bond without fulfilling the octet rule because hydrogen’s valence shell can hold only up to two electrons.
Hydrogen has one electron and needs one additional electron to fill its outer shell, which consists of just one energy level. Thus, when it forms a covalent bond (for example, by sharing an electron with another atom), it achieves a stable configuration by having two electrons in its valence shell, which is considered full in the case of hydrogen. The octet rule primarily applies to atoms that can accommodate eight electrons in their valence shell, typically nonmetals and some metals. In summary, hydrogen's stability is achieved by having two electrons, not necessarily adhering to the octet rule.
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