Question

In general, the properties that decrease and increase down a group in the periodic table respectively are:

• A. electronegativity and electron gain enthalpy.
• B. electronegativity and atomic radius.
• C. atomic radius and electronegativity.
• D. electron gain enthalpy and electronegativity.

Hint:

Electronegativity is the tendency of an atom to attract a shared pair of electrons towards itself. It decreases as we go down the group.

Answer 1

The Correct Option is B

To determine which properties decrease and increase down a group in the periodic table, we need to analyze the trends of electronegativity, atomic radius, and electron gain enthalpy. Here's a brief explanation of each property:

1. Electronegativity: This is a measure of an atom's ability to attract and hold onto electrons. As we move down a group in the periodic table, electronegativity generally decreases. This is because additional electron shells are added, which makes the valence electrons farther from the nucleus and lessens the effective nuclear charge experienced by these outer electrons.
2. Atomic Radius: The atomic radius is the distance from the nucleus to the outermost electron shell of an atom. As we descend a group, the atomic radius increases because more electron shells are added, increasing the size of the atom despite the increase in nuclear charge.
3. Electron Gain Enthalpy: This is the energy change when an electron is added to an isolated atom. The trend for electron gain enthalpy can be inconsistent, but it generally becomes less negative as we move down a group because adding an electron becomes less favorable with increasing distance from the nucleus.

Considering the above information, the correct option is:

electronegativity and atomic radius.

The correct reasoning is that as we move down a group, the electronegativity decreases due to the increase in distance between the nucleus and the outermost electrons. Meanwhile, the atomic radius increases because of the addition of extra electron shells. Therefore, the correct answer demonstrates the trend that electronegativity decreases and atomic radius increases as you move down a group in the periodic table.