Electron Mass, Electron Charge, Mole of Electrons, Avogadro Number and Faraday Constant Notes

 -Dr.Sanjaykumar pawar 

Electron Mass and Charge Explained for Beginners 

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FAQ 

What is the mass of an electron?

The mass of one electron is 9.108 × 10⁻²⁸ g or 9.108 × 10⁻³¹ kg.

What is the charge of an electron?

The charge of one electron is −1.602 × 10⁻¹⁹ C.

What is Avogadro Number?

Avogadro Number is 6.022 × 10²³ particles per mole.

What is one mole of electrons?

One mole of electrons contains 6.022 × 10²³ electrons.

What is the mass of one mole of electrons?

The mass of one mole of electrons is 5.48 × 10⁻⁴ g.

What is the Faraday Constant?

Faraday Constant is 96500 C, which represents the charge carried by one mole of electrons.

Why is Avogadro Number important?

It helps convert between moles and the actual number of particles in chemistry calculations.

NEET Chemistry Practice Questions

Electron Mass, Charge, Mole Concept & Faraday Constant

Q1. Calculate the number of electrons present in 2 g of electrons.

Solution:
Number of electrons in 1 g = 1.098 × 10²⁷

Therefore,
Number of electrons in 2 g
= 2 × 1.098 × 10²⁷
= 2.196 × 10²⁷

Answer: 2.196 × 10²⁷ electrons

Q2. What is the mass of 2 moles of electrons?

Mass of 1 mole electrons
= 5.48 × 10⁻⁴ g

Mass of 2 moles
= 2 × 5.48 × 10⁻⁴
= 1.096 × 10⁻³ g

Answer: 1.096 × 10⁻³ g

Q3. Calculate the charge carried by 2 moles of electrons.

Charge of 1 mole electrons
= 9.63 × 10⁴ C

Charge of 2 moles
= 2 × 9.63 × 10⁴
= 1.926 × 10⁵ C

Answer: 1.926 × 10⁵ C

Q4. How many electrons are present in 1 mole of electrons?

One mole contains Avogadro number of particles.

= 6.022 × 10²³

Answer: 6.022 × 10²³ electrons

Q5. What is the charge on 0.5 mole of electrons?

Charge of 1 mole
= 9.63 × 10⁴ C

Charge of 0.5 mole
= 0.5 × 9.63 × 10⁴
= 4.815 × 10⁴ C

Answer: 4.815 × 10⁴ C

Q6. Calculate the mass of 6.022 × 10²³ electrons.

6.022 × 10²³ electrons
= 1 mole electrons

Mass of 1 mole electrons
= 5.48 × 10⁻⁴ g

Answer: 5.48 × 10⁻⁴ g

Q7. Calculate the charge on 3.011 × 10²³ electrons.

3.011 × 10²³ electrons
= 0.5 mole electrons

Charge
= 0.5 × 9.63 × 10⁴
= 4.815 × 10⁴ C

Answer: 4.815 × 10⁴ C

Q8. How many moles of electrons are present in 1.2044 × 10²⁴ electrons?

Number of moles
= (1.2044 × 10²⁴)/(6.022 × 10²³)
= 2

Answer: 2 moles

Q9. What is the total charge carried by 6.022 × 10²⁴ electrons?

6.022 × 10²⁴ electrons
= 10 moles electrons

Charge
= 10 × 9.63 × 10⁴
= 9.63 × 10⁵ C

Answer: 9.63 × 10⁵ C

Q10. One Faraday is equal to how much charge?

One Faraday
= Charge on one mole of electrons
= 9.65 × 10⁴ C

Answer: 9.65 × 10⁴ C

Quick MCQ Revision

Q1. Charge of one electron is:
A. 1.6 × 10⁻¹⁹ C
B. 9.1 × 10⁻²⁸ C
C. 6.022 × 10²³ C
D. 9.65 × 10⁴ C

Answer: A

Q2. One mole electrons contain:
A. 9.65 × 10⁴ electrons
B. 6.022 × 10²³ electrons
C. 1.6 × 10⁻¹⁹ electrons
D. 10²⁷ electrons

Answer: B

Q3. Mass of one mole electrons is:
A. 5.48 × 10⁻⁴ g
B. 5.48 × 10⁴ g
C. 9.1 × 10⁻²⁸ g
D. 1 g

Answer: A

Q4. One Faraday equals:
A. 965 C
B. 9650 C
C. 96500 C
D. 965000 C

Answer: C

Q5. Number of electrons in 1 gram is:
A. 10²³
B. 10²⁴
C. 10²⁵
D. 1.098 × 10²⁷

Answer: D

Electron Mass, Electron Charge, Mole of Electrons, Avogadro Number and Faraday Constant

These are the most important concepts of Atomic Structure and Mole Concept. They are frequently asked in CBSE, NEET, JEE and other competitive examinations.

1. Electron Mass

An electron is a tiny negatively charged particle present outside the nucleus of an atom.

Mass of one electron:
9.108 × 10^-28 g
or
9.108 × 10^-31 kg

Important Point: The electron is extremely light. Its mass is about 1836 times smaller than the mass of a proton.

Memory Trick:
Electron Mass = 9 × 10^-28 g

Remember: "Electron = 9 Rule"

2. Electron Charge

Every electron carries a fixed negative electric charge.

Charge of one electron:
−1.602 × 10^-19 C

The negative sign indicates that the electron has a negative charge.

Important Point: All electrons have exactly the same charge.

Memory Trick:
Electron Charge = 1.6 × 10^-19 C

Remember: "Sweet 16 Charge"

3. Avogadro Number

Avogadro Number tells us how many particles are present in one mole.

Value:
6.022 × 10²³

These particles may be:

• Atoms
• Molecules
• Ions
• Electrons

Example:
1 mole electrons = 6.022 × 10²³ electrons

Memory Trick:
Remember: 6-0-2-2

This is the most important number in Chemistry.

4. Mole of Electrons

A mole is simply a counting unit in chemistry.

Just like:
1 dozen = 12 items
Similarly,
1 mole = 6.022 × 10²³ particles

Therefore,
1 mole electrons = 6.022 × 10²³ electrons

Mass of one mole of electrons:
5.48 × 10^-4 g

Quick Fact:
A single electron is very light, but one mole contains a huge number of electrons.

5. Faraday Constant

The total charge carried by one mole of electrons is called one Faraday.

Value:
96500 C
or
9.65 × 10⁴ C

Formula:
Faraday Constant = Charge of one electron × Avogadro Number

= (1.6 × 10^-19) × (6.022 × 10²³)

= 9.65 × 10⁴ C

Important Point:
1 Faraday = Charge carried by 1 mole electrons

Quick Revision Table

Quantity	Value
Electron Mass	9.108 × 10⁻²⁸ g
Electron Charge	1.6 × 10⁻¹⁹ C
Avogadro Number	6.022 × 10²³
1 Mole Electrons	6.022 × 10²³ electrons
Mass of 1 Mole Electrons	5.48 × 10⁻⁴ g
Charge of 1 Mole Electrons	9.65 × 10⁴ C
Faraday Constant	96500 C

Super Revision Trick

9 → 16 → 6

9 = Electron Mass
16 = Electron Charge
6 = Avogadro Number

Final Results

1 → 5 → 9
1 = 1.098 × 10²⁷ electrons in 1 gram
5 = 5.48 × 10⁻⁴ g
9 = 9.65 × 10⁴ C

Mnemonic:
"9-16-6 gives 1-5-9"