The Proper Definition of an Atom

An atom is the smallest unit of matter that retains the chemical properties of an element. It is composed of subatomic particles, including protons, neutrons, and electrons. The understanding of the structure of atoms is crucial in the field of chemistry and physics, as it provides insights into how elements interact and form compounds.

Structure of an Atom:
An atom consists of three main subatomic particles:

1. Protons: Protons carry a positive charge and are located in the nucleus, which is the central region of the atom. Each proton has a relative mass of 1 and is denoted by the symbol 'p+'.

2. Neutrons: Neutrons are neutral particles found in the nucleus alongside protons. They have a relative mass of 1 and are symbolized by 'n'. Unlike protons, neutrons do not carry an electric charge.

3. Electrons: Electrons are negatively charged particles that orbit the nucleus in specific energy levels or shells. They have a negligible mass compared to protons and neutrons. Electrons are denoted by 'e-'.

Atomic Number:
The atomic number of an atom refers to the number of protons present in its nucleus. It determines the element to which the atom belongs. For example, all hydrogen atoms have one proton, so the atomic number of hydrogen is 1. The atomic number is represented by the letter 'Z'.

Mass Number:
The mass number of an atom is the sum of its protons and neutrons. It is represented by the letter 'A'. For instance, if an atom has 6 protons and 6 neutrons, its mass number is 12. It is important to note that the mass number is not always equal to the atomic number, as isotopes (atoms with the same atomic number but different mass numbers) exist for some elements.

Video Explanation:
To gain a better understanding of the structure of atoms, you can refer to the video "Structure of Atoms (Atomic and Mass Number)" on EduRev. This video likely provides visual representations and explanations to help you grasp the concept more effectively. Just make sure to follow the guidelines and avoid promoting any external websites apart from EduRev.

The basic unit of a chemical element. (which is extremely small).