LEARNING OBJECTIVES:
- What is Atom?
- What is the building Block of chemistry?
- What is the structure of the atom?
- What are atomic particles?
- What is the mass and charge of basic subatomic particles?
- What is the net charge on an atom?
ATOM-THE BUILDING BLOCK OF CHEMISTRY
The atom is the smallest and fundamental unit of matter. The matter is anything that occupies space and has mass. Atom is made up of subatomic particles such as protons, electrons, and neutrons, etc. These subatomic particles define the properties of atoms. In a chemical reaction, atoms arrange themselves and form useful molecules. The atoms, their numbers, and their arrangement determine the chemical properties of the resultant molecule. For example, water is made up of 2 hydrogens and 1 oxygen atom, but if 2 hydrogen and 2 oxygen atoms combine then they form hydrogen peroxide. So we can define atom as a basic building block of chemistry.
Atomic particles:
As we have discussed before that atom is made up of subatomic particles such as electrons, protons, and neutrons. Every atom is made up of a nucleus which is made up of protons and neutrons. Protons are positive charge particles and neutrons are neutral. Therefore, the net charge on the nucleus of an atom is positive. The electrons which is a negative charge particle it revolves around the nucleus on paths called electronic shells.
Mass and charge of particles:
Mass of proton is nearly equal to the mass of the neutron, but the electron is many times lighter than proton or neutron about 1836 times than proton, and 1840 times than neutron.
- Mass of proton = 1.673 X 10 ^ -27 kilograms
- Mass of neutron = 1.675 X 10 ^ -27 kilograms
- Mass of electron = 9.109 X 10 ^ -31 kilograms
Charge on electron and neutron is same i.e. 1.6 X 10 ^ -19 C but with opposite signs. Proton has a positive and the electron has a negative charge while the charge on neutron is zero.
The net charge on the atom:
An atom is electrically neutral. There is an equal number of protons inside the nucleus and electrons that revolve around the nucleus. As the proton carries a relative charge of +1 and the electron carries a relative charge of -1. They both cancel each other's effect so the net charge on the atom becomes zero.
For instance: Helium atom contain 2 protons,2 neutrons and 2 electrons so the net charge on helium atom is (+1 X 2) + (0 X 2) + (-1 X 2) = 0
SUMMARY:
- Atom is the basic building block of chemistry
- Atoms are made up of subatomic particles such as electrons, protons, and neutrons.
- Proton and neutron are heavier than an electron but the charge of a proton is equal to the charge of electron and neutron is electrically neutral.
- Atoms arrange and organize to form different molecules.
- Atom is electrically neutral. The number of protons is equal to the number of electrons.