If you move from top to bottom in a group in the periodic table, valency:AincreasesBdecreasesCincreases then decreasesDremains the same

Break Down the Problem

1. Understand the concept of valency in the context of the periodic table.
2. Analyze how valency changes as you move from top to bottom.

Relevant Concepts

• Valency: Refers to the ability of an atom to bond with other atoms, often determined by the number of electrons in the outermost shell.
• Periodic Table Trends: Moving down a group generally increases the number of electron shells, affecting the atom's bonding behavior.

Analysis and Detail

1. Electron Shells: As you move down a group in the periodic table, the number of electron shells increases. This typically leads to:

   • An increase in atomic size.
   • A decrease in electronegativity.
   • An increase in shielding effect.

2. Valency Changes:

   • For metals in a group, the tendency to lose electrons increases as the outer electrons are further from the nucleus, leading to an increase in metallic character and potential oxidation states.
   • For non-metals, while some may increase in valency (like halogens forming -1 to +7 states), generally, their reactivity can decrease due to the increased distance from the nucleus affecting electron gain.

Verify and Summarize

The simplest conclusion is that valency can show varied behavior depending on whether you are moving through metals or non-metals. However, in general terms, it can be stated that:

• For most groups, especially metals, the valency tends to either increase or remain relatively constant but will not significantly decrease.

Final Answer

The correct answer is A increases. Valency tends to increase as you move from top to bottom in a group of the periodic table, particularly for metals.