Structure of an atom

Question 1 Name the building blocks of matter?

Question 2 Name the subatomic particles in atoms?

Question 3 Give an example to show that there are charged particle in matter?

Structure of an atom

Atoms and molecules are the building blocks of matter.

Atoms are made up of three subatomic particles:electrons,protons,neutrons.
Electrons are negatively charged,protons are positively charged and neutrons has no charge.
Protons and neutrons are present in a small nucleus at the centre of an atom.

The entire mass of the atom is in the nucleus because the electrons ,which are outside the nucleus have very very small mass.Electrons are outside the nucleus.The electrons in an atom revolve rapidly round the nucleus in fixed circular paths called energy levels or shells.The number of electrons is equal to number of protons.

The atoms of different elements differ in the number of electrons,protons and neutrons.

Hydrogen atom is made up of only one electron and one proton.It does not contain any neutron.

Charged particle in Matter
1)If we rub a comb in dry hairs,then this comb attracts small pieces of paper.
2)If we rub a glass rod with a piece of silk cloth and bring it near an inflated balloon,the glass rod attract the balloon.

An electrically charged object attracts an uncharged object. On rubbing with dry hair,a comb gets an electric charge and on rubbing with silk cloth a glass rod gets an electric charge.This shows that some charged particles are present in the atoms of matter.

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