Molecule — অণু

Definition

A molecule is a group of two or more atoms held together by covalent bonds — the smallest particle of a covalent substance that still behaves like that substance. Molecules may hold one kind of atom, like the $\mathrm{O_{2}}$ and $\mathrm{O_{3}}$ of oxygen, or several kinds, like $\mathrm{H_{2}O}$, $\mathrm{CO_{2}}$ and $\mathrm{NH_{3}}$. A single grain of sugar carries nearly two billion billion molecules, all identical and each one sweet. Chemists count molecules in moles: one mole holds 6.022 × 10²³ of them.

For example

One water molecule ($\mathrm{H_{2}O}$) is always two hydrogen atoms bonded to a single oxygen at 104.5°; the ozone ($\mathrm{O_{3}}$) molecules high in the stratosphere soak up the Sun's harsh ultraviolet rays.

Elements this touches

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