Question

The atomic radii in periodic table among elements from right to left:
A. Decreases
B. Increases
C. Remain constant
D. First decreases and then increases

Answer 1

Hint: Atomic radius is very important when trying to explain the size of molecules of compounds. It says why some fit together and why others have parts that get too crowded. To answer this question you can imagine what will happen when number of electrons increases or decreases

Step by step answer: Atomic radius of a chemical element is a measure of the size of its atoms usually it is the mean or typical distance from the centre of the nucleus to the boundary of the surrounding shells of electrons.
The radii of isolated neutral atoms mostly range between 30 and 300 \[pm\] (trillionths of a meter). That is the radius of an atom is more than 10,000 times the radius of its nucleus and less than \[1/{1000^{th}}\] of the wavelength of visible light.

Atomic radii are divided into three types. They are covalent radius, Van der Waals radius and metallic radius. Covalent radius is one half the distance between the nuclei of two covalently bonded atoms of the same element in a molecule. The internuclear distance between two bonded atoms is called the bond-length.

Van der Waals radius is one half the distance between the nuclei of two identical non-bonded isolated atoms or two adjacent identical atoms belonging to two neighbouring molecules of an element in the solid state. This type of radius is dependent on the packing of the atoms when the element is in solid state.

Metallic radius is the force of attraction between the mobile electrons and the positive kernels. It is one half of the internuclear distance between two adjacent metal ions in the metallic lattice.

Due to the increase in the number of electrons and protons from left to right, the atomic radius decreases from left to right within a period. As the number of electrons and protons increases, the central force pulls the electrons towards the nucleus resulting in smaller radius. Therefore, atomic radii increase from right to left in the periodic table.

So, the correct answer is option B.

Note: There are always some exceptions in every situation. We have some exceptions here also. For example, oxygen radius is slightly greater than nitrogen radius.