Science Question Answer (1 Marks)

Electron is negatively charged particle present in atoms of all the elements.

Three subatomic particles present in atom are electrons, protons and neutrons.

Isobars are the atoms of different elements having different atomic numbers but the same mass number (or same atomic mass).

Neutron is not present in ordinary hydrogen atom.

Radioactive isotopes are used in industry to detect the leakage in underground oil pipelines, gas pipelines and water pipes.

1. 8 electrons are present in outermost shell of Neon.
2. 7 electrons are present in outermost shell of Chlorine.

1. Proton has relative charge of +1.
2. Electron has relative charge of -1.
3. Neutron has relative charge of 0.

K, L, M, N were the letters used by Bohr to represent electron shells in an atom.

Proton is the positively charged particle present in atoms of all the elements.

Due to slight difference in the masses of the isotopes of an element, the physical properties of the isotopes are slightly different.

Protons are positively charged particle found in the atoms of all the elements whereas neutron is a neutral particle found in the nucleus of an atom.

Positive charge on the nucleus is due to presence of protons.

Proton is 1840 times heavier than electron.

1. Chadwick discovered ‘neutron’.
2. Thomson discovered ‘electron’.
3. Goldstein discovered ‘proton’.

Atomic No. = 17
E.C. = (2, 8, 7)
Valency = 8 - no. of valence electrons
Valency = 8 - 7
Valency = 1

Electronic configuration of given element (2, 8, 3) K-2, L-8, M-3.