Which of the following characteristics regarding halogens is not correct? a)Ionization energy decreases with increase in atomic number. b)Electronegativity decreases with increase in atomic number. c)Electron affinity decreases with increase in atomic number. d)Enthalpy of fusion increases with increase in atomic number.Correct answer is option 'C'. Can you explain this answer?

Question

Answer

Explanation:

Ionization energy:
Ionization energy is the energy required to remove an electron from an atom or ion. In the case of halogens, the ionization energy generally decreases with an increase in atomic number. This is because as the atomic number increases, the size of the atom increases, and the outermost electron is farther away from the nucleus. As a result, the attractive force between the nucleus and the outermost electron decreases, making it easier to remove the electron.

Electronegativity:
Electronegativity is a measure of an atom's ability to attract electrons towards itself in a chemical bond. In the case of halogens, electronegativity generally increases with an increase in atomic number. This is because as the atomic number increases, the number of protons in the nucleus increases, leading to a stronger positive charge. As a result, the nucleus has a greater ability to attract electrons towards itself.

Electron affinity:
Electron affinity is the energy change that occurs when an electron is added to a neutral atom to form a negative ion. In the case of halogens, electron affinity generally increases with an increase in atomic number. This is because as the atomic number increases, the size of the atom decreases, and the outermost electron is closer to the nucleus. As a result, the attractive force between the nucleus and the incoming electron increases, making it easier to add an electron.

Enthalpy of fusion:
Enthalpy of fusion is the amount of heat required to change a substance from solid to liquid at its melting point. In the case of halogens, the enthalpy of fusion generally increases with an increase in atomic number. This is because as the atomic number increases, the size of the atom increases, and the forces of attraction between the atoms in the solid state become stronger. As a result, more heat energy is required to break these forces and convert the solid halogen into a liquid.

Conclusion:
Among the given options, the statement that electron affinity decreases with an increase in atomic number for halogens is incorrect. In reality, electron affinity generally increases with an increase in atomic number for halogens.

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Following statements regarding the periodic trends of chemical reactivity of the alkali metals and the halogens are given. Which of these statements gives the correct picture ?

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