Name: Electrovalency
Uploaded: 2019-07-19
Duration: 1 min 51 s
Description: Do you know how chemical bonds are formed? They are formed in order to attain a stable electronic configuration. Let's watch the video to learn about the pro...

Question

Give the name of the scientist who discovered the electron. Describe the experiment conducted for the discovery of electrons. How are the mass and charge of electrons determined?

Accepted Answer

J. J. Thomson proved the existence of electrons in $1987$ . J.J.Thomson's experiments with cathode-ray tubes have shown that all atoms contain tiny negatively charged subatomic particles or electrons. He found that beam of negatively charged rays emitted from the cathode in the discharge tube. Cathode rays consist of negatively charged particles later named as electrons.

J. J. Thomson studied the combined effect of electric and magnetic fields on cathode rays. J. J. Thomson balanced the effect of both electric and magnetic fields to produce no deflections in the cathode rays beam. From this, Thomson calculated the charge/mass ratio, that is, $\frac{e}{m}$ ratio $(1.759 \times 10^{11} {CKg}^{- 1})$ .

American chemist, Robert A Millikan measured the charge on an electron by carrying out an oil drop experiment. He noticed that the charge was always a multiple of $- 1.602 \times 10^{- 19} C$ , the charge on a single electron.

Mass of an electron is calculated by using the values of $\frac{e}{m}$ as follows:

The $\frac{e}{m}$ value is $1.759 \times 10^{11} C {Kg}^{- 1}$ and charge of an electron (e) is $1.602 \times 10^{- 19} C$ .

Then, the mass of the electron (m) $= \frac{charge}{(charge / mass)} = \frac{e}{(\frac{e}{m})} = m = \frac{1.602 \times 10^{- 19} C}{1.759 \times 10^{11} C {Kg}^{- 1}} = 9.109 \times 10^{- 31} Kg .$

Give the name of the scientist who discovered the electron. Describe the experiment conducted for the discovery of electrons. How are the mass and charge of electrons determined?

Important Questions on Structure of the Atom

Learn and Prepare for any exam you want !