Answer:
1. Dalton..........Father of Atomic theory
2. Bohr..........Postulated the quantum atom
3. nucleus..........location of the most of the mass of the atom
4. Chadwick..........discovered the neutron
5. Rutherford..........discovered the proton
6. electrons..........emitted from a cathode-ray tube
7. J.J. Thomson..........discovered the electron
Explanation:
The question is incomplete.Here is the cmplete question.
Match these items.
1. Dalton...... emitted from a cathode-ray tube
2. Bohr.......... discovered the neutron
3. nucleus.......... discovered the electron
4. Chadwick........ postulated the quantum atom
5. Rutherford........... discovered the proton
6. electrons ............father of atomic theory
7. J. J. Thomson.............location of most of the mass of the atom
1) Dalton is the father of atomic theory
He proposed that matter comprises of indivisible particles called atoms. Atoms are the building block of a matter. All atoms of an element are identical. Atoms of different elements differ from each other in terms of size and mass.
2. Bohr postulated the quantum atom
He proposed that electrons revolve around the nucleus in orbits. Each orbit is labelled by an integer 'n’. This integer is the quantum number. Electrons can move between shells by emitting or absorbing energy.
3. Nucleus is the location of most of the mass of the atom
The entire mass (almost 99%) of atom is concentrated in the nucleus containing protons and neutrons. Electrons orbiting around have negligible mass compared the protons and neutrons.
4. Chadwick discovered the neutron.
In an experiment, Chadwick bombarded beryllium atoms with alpha rays. He noticed that beryllium emitted neutral rays as a result. Unlike gamma rays, the rays did not create photo electric effect when they hit charged electroscope. He concluded that they are neutrons instead.
5. Rutherford discovered the proton
In his famous gold foil experiment, he bombarded positively charged alpha rays to gold foil as saw a large proportion of them being deflected. He concluded that the atoms must have positively charged particles that caused the deflection.
6. Electrons are emitted from a cathode-ray tube
When electricity is passed through the cathode in the tube, electrons in the outermost orbit gain enough energy to break out from it
7. J. J. Thomson discovered the elections.
In the cathode-ray tube, Thompson observed that the rays emitted from the cathode are deflected towards to the positively charged plate. He concluded that cathode rays composed of negatively charged particles, i.e. electrons.
