All houses are made of bricks. In the same manner, atoms and molecules are the building blocks of matter. An atom is a small particle when group together form a molecule. Similarly, a group of molecules of same or different kind combines to form matter. All atoms are so small that we cannot see even under a highly powerful optical microscope. Electron microscopes can produce an extremely magnified image of a tiny object. The most advanced type of electron microscope and its name is scanning tunneling microscope (STM).This microscope can produce computer-generated images which show in visuals.
- The hydrogen atom is the smallest of all atoms.
What are Atoms and Molecules?
|Atoms are the smallest particle of an element which can take part in a chemical reaction. It may or may not be capable of Independent existence.|
For example, the atoms of hydrogen are not capable of independent existence while the atoms of neon gas are capable of independent existence.
- These are very very small in size. It’s an idea about 35 crore copper atom cover the distance of 1 cm.
- The size of an atom indicates the atomic radius.
- Units of the atomic radius are nanometer. A nanometer is a very small unit of measuring length.
- An atom has the properties of an element.
- Its sub-particles are Electrons Protons and Neutrons.
|It is the smallest particle of a substance (element or compound) which is capable of independent existence.|
Difference between Atoms and Molecules
|An atom in the smallest particle of an element which can take part in a chemical change.||A molecule is the smallest particle of a substance (element or compound).|
|It may or may not be capable of independent existence.||It is capable of independent existence.|
|It can be broken into still smaller fragments like electrons, protons & neutrons. But atom is the smallest unit for a chemical reaction.||A molecule may contain one, two or more atom. Except for monoatomic molecules(H2, Cl2), others can be seprate into the constituent atoms.|
|Examples – O (oxygen), N (nitrogen), S (sulphur)||Examples – Water (H2O), Carbon dioxide (CO2), Hydrogen sulphide (H2S)|
How are Atoms and Molecules Related?
Molecules are generally made up of two or more atoms of the same or different elements. Thus molecules are of two types: Molecule of an element, Molecule of a compound.
Molecule of an Element
A molecule of an element contains two or more atoms of the same element. For example, a molecule of hydrogen(H2) consists of two atoms of hydrogen. Such molecules are term as diatomic molecules. Other examples of diatomic molecules are Cl2, O2, N2. On the other hand, ozone(O3) contains three oxygen and is a triatomic molecule.
It may be mentioned that the molecules of noble gases such as helium, neon, argon, krypton, and xenon are monatomic molecules. This is because each of these gases contains only one atom.
- The number of atoms in a molecule of the element is called its atomicity.
Molecule of a Compound
A molecule of a compound contains two or more atoms of the different elements. For example, a molecule of hydrogen chloride (HCl) contains one atom of hydrogen and one atom of chlorine. Since a molecule of hydrogen chloride contains two atoms, it is also called diatomic molecule. On the other hand, a water (H2O) contains two hydrogens and one atom of oxygen. A molecule containing more than three atoms are called polyatomic molecule. It may be mentioned that the molecules of some of the natural products are quite complex and contain a very large number of atoms. For example, a molecule of sugar cane (C12H22O11) contains 45 atoms.
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