Test: Model Of An Atom

Sir James Chadwick, 20 October 1891 – 24 July 1974 was a British physicist who was awarded the 1935 Nobel Prize in Physics for his discovery of the neutron in 1932.

When we rub a glass rod with a silk cloth, the glass rod gets charged. This charge produced on the rod comes from the atoms and charged particles present in the rod.

The proton has a charge equal in magnitude but opposite in sign to that of electron.

A proton has one unit positive charge whereas electron has one unit negative charge.

An anode ray (also positive ray or canal ray) is a beam of positive ions that is created by certain types of gas-discharge tubes. They were first observed in Crookes tubes during experiments by the German scientist Eugen Goldstein, in 1886.

Eugen Goldstein

They were first observed in Crookes tubes during experiments by the German scientist Eugen Goldstein, in 1886. Later work on anode rays by Wilhelm Wien and J. J. Thomson led to the development of mass spectrometry.

There is only one stable atom that does not have neutrons. It is an isotope of the element hydrogen called protium. Protium, which contains a single proton and a single electron, is the simplest atom. All other stable atoms contain some number of neutrons.

Cathode rays are beam of electrons which are negatively charged. These electrons are identical. Hence, the charge to mass ratio (e/m) of cathode rays is same for all the gases.

Whereas, in case of anode rays, they are positively charged. Also, they are composed of ionised nuclei which vary from gas to gas in terms of atomic number and mass number. Thus, charge to mass ratio (e/m) of the positively charged ions changes as the number of nucleons changes in the nucleus of each gas can be different.

An electron is a negatively charged particle, whereas a proton is a positively charged particle. The magnitude of their charges is equal. Therefore, an atom containing one electron and one proton will not carry any charge.

Electron and proton were embedded in nucleus as said in watermelon experiment.

Canal rays are positively charged radiations which led to the discovery of another sub-atomic particle called protons.

J. J. Thomson, who discovered the electron in 1897, proposed the plum pudding model of the atom in 1904 before the discovery of the atomic nucleus in order to include the electron in the atomic model. In Thomson's model, the atom is composed of electrons (which Thomson still called “corpuscles,” though G. J.

Subatomic particles include electrons, the negatively charged, almost massless particles that nevertheless account for most of the size of the atom, and they include the heavier building blocks of the small but very dense nucleus of the atom, the positively charged protons and the electrically neutral neutrons.

Thomson proposed the model of an atom to be similar to that of a Christmas pudding. The electrons, in a sphere of positive charge, were like currants (dry fruits) in a spherical Christmas pudding.

The essential conditions for the production of anode rays is high voltage and very low pressure in a discharge tube.

Here it means that when we compare the mass of protons and electrons. Electrons weigh much less than protons and therefore when the mass of an atom is calculated then just the mass of protons and neutrons is taken into consideration.