Question

The energy needed to break the crystal into individual atom is called:

• A. Ionization Potential
• B. Cohesive energy
• C. Electron affinity
• D. Work function

Hint:

Cohesive energy measures how strongly atoms are bound in a crystal.

Answer 1

The Correct Option is B

Concept:
Cohesive energy is the energy required to separate a solid crystal into isolated neutral atoms.

Step 1: Understand crystal binding.
Atoms in a crystal are held together by bonding forces. \[ \text{Crystal} \rightarrow \text{atoms bonded together} \]

Step 2: Energy required to separate atoms.
To break the crystal into individual atoms, energy must be supplied to overcome the bonding forces. \[ \text{Energy required}=\text{Cohesive energy} \]

Step 3: Eliminate other options.
Ionization potential is energy required to remove an electron from an atom.
Electron affinity is related to energy change when an electron is added.
Work function is energy required to remove an electron from a metal surface. \[ \therefore \text{Correct Answer is (B)} \]