In the periodic table, as one goes down the group, which property doesn't change?

Correct option is C

The correct answer is: (c) Valency

Explanation:

• Valency generally remains the same as we move down a group in the periodic table. This is because valency is determined by the number of electrons in the outermost shell (valence electrons), and for elements in the same group, the number of valence electrons remains the same.

• For example, elements in Group 1 (like Lithium (Li), Sodium (Na), Potassium (K)) all have 1 valence electron, so their valency is 1.

Information Booster:

• Number of shells: (Incorrect) As we go down a group, the number of electron shells increases, resulting in a larger atomic radius.

• Metallic character: (Incorrect) Metallic character increases as we move down a group due to the decrease in ionization energy and the ease with which electrons are lost.

• Atomic size: (Incorrect) Atomic size increases as we go down a group because additional electron shells are added, making the atom larger.

Additional Information:

• Valency remains the same in a group because elements in the same group have the same number of valence electrons, and therefore, they have the same chemical reactivity.

• Example: Group 17 (Halogens) elements, like Fluorine (F), Chlorine (Cl), Bromine (Br), all have 7 valence electrons and exhibit valency of 1.