Ancient Thinkers
Who proposed the concept of Parmanu?
Kanada
Who discovered the electron?
J. J. Thomson
Which particle has a positive charge?
Proton
Atomic number is equal to the number of ______.
Protons ( Electrons)
Maximum number of electrons in the K shell?
2
What is the Greek word meaning "indivisible"?
Atomos
Which atomic model is called the Plum Pudding Model?
Thomson's model
Who discovered the neutron?
Chadwick
Mass number is the sum of which two particles?
Protons and Neutrons
Write the electronic configuration of sodium.
2, 8, 1
Who proposed the first scientific atomic theory?
Dalton
Which experiment led to the discovery of the nucleus?
Gold foil experiment
Which subatomic particle has the least mass?
Electron
An atom has 17 protons and 18 neutrons. Find its mass number.
35
What is the valency of oxygen?
2
Dalton considered atoms to be indivisible. Which later discovery proved this idea incorrect?
Discovery of subatomic particles (electron/proton/neutron)
Which scientist explained atomic stability using fixed energy levels?
Bohr
Which particle adds mass but has no charge?
Neutron
An atom has mass number 56 and atomic number 26. How many neutrons does it have?
30
Write the electronic configuration and valency of chlorine.
2, 8, 7; Valency= 1
Name the two ancient civilizations that independently proposed the idea of indivisible particles.
India and Greece
Why was Rutherford's atomic model considered incomplete?
It could not explain the stability of electrons revolving around the nucleus.
Arrange electron, proton, and neutron in increasing order of mass.
Electron < Proton ≈ Neutron
An atom has 20 protons, 20 electrons, and 21 neutrons. Identify its atomic number and mass number.
Atomic number = 20; Mass number = 41
An element has atomic number 13. Write its electronic configuration and valency.
2, 8, 3; Valency= 3