A molecule is the smallest particle of an element or compound capable of an independent life and exhibiting all of the substance's properties.
Molecule:
In general, a molecule is a set of two or more atoms that are chemically bound or held together by attractive forces.
Atoms from the same or different elements may combine to form a molecule.
Atoms from the same or different elements may combine to form a molecule.
Example:
For simple understanding, consider a water molecule; two elements, hydrogen and oxygen atoms combined to form a water molecule.
Calcium oxide \(CaO\) contains two elements, calcium and oxygen atoms combined to form a calcium oxide molecule.
Glucose \(C_6H_{12}O_6\) contains three elements, carbon, hydrogen and oxygen atoms combined to form a glucose molecule.
Sodium chloride \(NaCl\) contains two elements; hydrogen and oxygen atoms combined to form a sodium chloride molecule.
Chlorine \(Cl_2\) contains two elements of a chlorine atom.
Oxygen \(O_2\) contains two elements of the oxygen atom.
Atomicity:
We can distinguish the molecules respective to the number of elements they combined to form a molecule. We call this atomicity .i.e. the number of atoms constituting a molecule.
The number of atoms present in a single molecule is termed as its atomicity.
Molecules of Elements:
The atoms that make up an element's molecules are all of the same nature.
- Monoatomic Elements: In their molecular form, certain elements are monatomic, meaning they are made up of just one atom (mono-atomic). Helium \(He\) is an example of a monoatomic element.
- Diatomic Elements: If the molecule constitutes two atoms, we can classify it as a diatomic molecule. In their molecular shape, other elements have two or more atoms. For example, each molecule of hydrogen \(H_2\), oxygen \(O_2\), and chlorine \(Cl_2\), has two atoms.
- Triatomic Elements: If another atom is combined with , it forms ozone, which is a triatomic molecule.
Note:
Monoatomic and diatomic molecules are more stable than triatomic molecules.
Most non-metal elements are diatomic.
Classification of elements | Name of the elements | Symbol | Atomicity |
Metals | Copper | \(Cu\) | Monoatomic |
Aluminum | \(Al\) | Monoatomic | |
Sodium | \(Na\) | Monoatomic | |
Iron | \(Fe\) | Monoatomic | |
Non-metals | Nitrogen | Diatomic | |
Hydrogen | Diatomic | ||
Oxygen | Diatomic | ||
Helium | \(He\) | Monoatomic | |
Chlorine | Diatomic | ||
Ozone | Triatomic | ||
Phosphorous | Tetra-atomic |
Molecules of Compounds:
Compound molecules contain atoms from two or more separate elements.
Example:
Water (H2O), has three atoms: two hydrogens \(H\) atoms and one oxygen \(O\).
Methane (CH4), has with five atoms: one carbon \(C\) and four hydrogen \(H\) atoms.
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