Chemistry 2008 JAMB Past Questions - Question 10: In the periodic table, electrical and thermal conductivities are properties of elements that

Correct Answer

A

Explanation

In the periodic table, electrical and thermal conductivities are properties of elements that generally decrease across a period and increase down a group. Here's the breakdown:

• Across a period: As elements gain protons and electrons, their valence electrons (electrons in the outermost shell) become increasingly tightly bound to the nucleus. This makes it harder for them to move freely and carry heat or electricity, so conductivity generally decreases.
• Down a group: As elements add more shells of electrons, the valence electrons are further away from the nucleus and experience less attraction. This makes them more free to move, leading to an increase in conductivity.

However, it's important to remember that this is a general trend, and there are exceptions. For example, some non-metals like graphite are good conductors due to their unique molecular structures. It's always best to consult a specific element's properties when needed.