Electrons are negatively charged subatomic particles that can be free or attached to atoms. The energy levels of an electron in atoms are represented by circular shells of various radii.

Mass Of Electron: Formula, Rest Mass, Mass Ratio

Q: Determine the value of the mass of an electron in grams.

The mass of electrons in kilograms is 9.1 × 10-31 kg. Since 1 kg = 1000 g, the mass of electrons in grams is 9.1 × 10-28 g.

Q: Do protons and electrons weigh the same?

Electrons are subatomic particles that are negatively charged. Protons and neutrons have the same weight but are much larger than electrons (about 2,000 times as big as electrons).

Q: What is the size of a single proton?

A proton is a stable subatomic particle occurring in all atomic nuclei with a fine charge equivalent in magnitude to that of an electron. It has a resting mass of 1.67262 1027 kg which is 1,836 times the size of an electron.

Q: What is the meaning of electron transition?

Electron transition refers to the change (or jump) of an electron from one energy level to another within an atom or artificial atom.

Q: Where do protons get their weight from?

Protons are made up of three quarks that are bound together by gluons, which are particles that carry a strong force. The mass of a proton is about 80-100 times greater than the sum of the remaining masses of its three quarks, while the gluons have zero rest mass. Almost 99% of the mass of protons and neutrons is determined by the force of the interaction between quarks and gluons.

Q: What are the properties of Electrons?

Every matter comprises atoms which contain protons, neutrons, and electrons. Electrons are negatively charged particle that contains the following properties: Electrons spin around the nucleus like planets around the sun. The rest mass of an electron is 9.1 × 10-31 kg or 5.489 × 10-4 amu.

Q: Name an experiment that led to the discovery of electrons and explain how?

J.J. Thomson performed the cathode ray discharge tube experiment which led to the discovery of electrons. A cathode ray tube consists of two thin pieces of metal called electrodes sealed inside a glass tube with sealed ends. The glass tube was partly evacuated and then attached to a vacuum pump and the pressure inside the tube was reduced to 0.01mm. When a fairly high electric voltage (10,000 V) is applied at either end of the tube between two electrodes, invisible rays are emitted from the cathode called cathode rays. The analysis of these rays called the cathode rays led to the discovery of electrons

Mass Of Electron

Archana S,

Mar 4, 2024

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The mass of electron is the mass of a stationary electron described by the equation me = 9.10938356 × 10-31 kilograms where me is the rest mass of electron.

Table of Contents

Value of Mass of Electron
Rest Mass of Electron
Determination of Charges for Mass Ratio of Electrons

The mass of electron is ¹/₁₈₃₆ of the proton mass, denoted by me = 9.10938356 × 10^-31 kilograms. It is the mass of a stationary electron and is also known as the invariant mass of electron. The mass of an electron is a fundamental constant of physics expressed in various units like amu (atomic mass units), eV (electro volts), etc.

Value of Mass of Electron

As per the special theory of relativity, the mass of any object varies according to the frame of reference. Therefore, the mass of electron can also be considered as rest mass which has an energy equivalent of approximately 8.187 × 10^-14 Joules. Electrons have a coefficient of -1 and weigh 0 ounces (atomic mass unit) around the nucleus.

Charge, mass, spin, and other properties are passed down to an electron. The electron charge, mass, and quantum mechanical properties known as electron spin are all represented in terms of their respective units by the values of electrons.

Charge of Electron

The electric charge by an Electron is the unit elementary negative charge.

The value is: e^– = 1.60217662 × 10^-19 coulombs

The charge of an electron is responsible for the electric charge.

Mass of Electron

The mass of an electron is 1/1836 of proton mass.

The value of electron mass is: m_e = 9.10938356 × 10^-31 kilograms

The values of charge and mass of electrons are commonly used in solving problems in physics.

Electron Spin

Spin or angular momentum are intrinsic quantum mechanical properties of subatomic particles.

The spin of an electron is half-integral values: s = ½

Rest Mass of Electron

The mass of a stationary electron can be calculated through spectroscopic measurement and the Rydberg Constant. The formula for the mass of electron is shown below:

The values of the mass of electrons in different units are shown in the table below:

Units	Mass of Electron
kg	9.10938356 (11) × 10^-31
grams	9.10938356 (11) × 10^-28
amu	5.48579909070 (16) × 10^-4
ev	0.5109989461 (31)

Determination of Charges for Mass Ratio of Electrons

Electrons were discovered back in the 19th century by J.J Thomson when he proposed Thomson’s Atomic Model. An experiment was conducted to determine the charge and mass of electrons.

The charge-to-mass ratio of the electrons was determined by conducting accurate measurements on the number of deflections observed by the electrons in the electric field and magnetic field. The charge-to-mass ratio of electrons is given by,

e/m = 1.758820 × 1011 C/kg

where m = mass of electron = 9.10938356 × 10^-31 kg

e = charge of the electron = 1.602 × 10^-19coulombs

Experimental Set-Up to Determine Charges for Mass Ratio of Electron

J.J. Thomson conducted a discharge tube experiment in which he observed that the particles in the cathode showed a deviation from their path. The extent of this deviation depends upon the different parameters mentioned below:

The particles with a higher magnitude of the charge experienced greater interaction with the electric and magnetic field and thus showed greater deflection.
The particles with a lower mass also experienced greater deflection. Therefore, deflection is inversely proportional to the mass of electron.
The deflection shown by the particles is directly proportional to the strength of the electric and magnetic fields.

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