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Which of the following elements is monoatomic?
Helium
Nitrogen
Oxygen
Hydrogen
Helium
A monoatomic element is one that exists as single atoms in its standard state, meaning it does not form covalent bonds with itself. Among the given options, Helium (He) is a noble gas and is therefore monoatomic, while Nitrogen (N2тАЛ), Oxygen (O2тАЛ), and Hydrogen (H2тАЛ) are diatomic.
A monoatomic element is one that exists as single atoms in its standard state, meaning it does not form covalent bonds with itself. Among the given options, Helium (He) is a noble gas and is therefore monoatomic, while Nitrogen (N2тАЛ), Oxygen (O2тАЛ), and Hydrogen (H2тАЛ) are diatomic.
Think of Helium atoms like independent loners in a party who are perfectly happy and complete on their own, whereas Nitrogen, Oxygen, and Hydrogen atoms are like people who prefer to hold hands with a partner to feel stable and secure.
HE, NE, AR, KR, XE, RN тАФ All noble gases are loners (monoatomic).
He тАФ Molecular formula of monatomic Helium
N2тАЛ тАФ Molecular formula of diatomic Nitrogen
Monoatomic nature is a characteristic of Group 18 elements (noble gases) because they possess a stable, fully-filled valence electron configuration (octet or duplet). This stability means they have little tendency to gain, lose, or share electrons, and thus do not form stable chemical bonds with other atoms of the same element under normal conditions.
Noble gases possess a stable electronic configuration with a complete valence shell.
Diatomic molecules (O2тАЛ,N2тАЛ,H2тАЛ) share electrons to achieve stability.
Monoatomic elements remain as individual atoms in the gas phase at standard temperature and pressure.
High chemical inertness due to complete valence shells
Helium is used in cryogenic cooling because of its low boiling point.
Helium is used in weather balloons and deep-sea diving gas mixtures.
Noble gases: Helium, Neon, Argon, Krypton, Xenon, Radon.
Option B (Nitrogen) exists as a NтЙбN triple-bonded diatomic molecule.
Option C (Oxygen) exists as O=O double-bonded diatomic molecule.
Option D (Hydrogen) exists as HтИТH single-bonded diatomic molecule.
A is correct тАФ Helium is a noble gas that exists as individual atoms, making it monoatomic.
Always remember the seven common diatomic elements (H, N, O, F, Cl, Br, I) to easily eliminate them in questions about atomicity.
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