Rank the following elements in INCREASING Atomic Radius: Fe, Ni, K, Ti (SMALLEST TO LARGEST)
a. Ti, Ni, Fe, K
b. Ni, Fe, Ti, K
c. Fe, Ti, K, Ni
d. K, Ti, Fe, Ni

b. Ni, Fe, Ti, K

Explanation:

The given elements are present in period 4 of periodic table. Now we will discuss the trend of atomic radius along period.

Atomic radius:

" It is the smallest distance from nucleus to the outer most valance shell of an atom"

When we move from left to right in the periodic table the number of valance electrons in an atom increase. The atomic size goes to decrease in same period because of edition of electron with in the same shell. When the electron are added, at the same time protons are also added in the nucleus. In this way positive charge is also going to increase and this charge is greater in effect than the charge of electrons. This effect causes the greater nuclear attraction. The electrons are pull towards the nucleus and valance shell come closer to the nucleus.

As a result of this greater nuclear attraction atomic radius decreases and ionization energy increases because it is very difficult to remove the electron from atom and more energy is required.

Ni ∠ Fe ∠ Ti ∠ K

the correct option is c.

isotopes refers to different forms of the same element with the same atomic number but different mass number as a result of difference in their neutron numbers. isotopes have different relative atomic mass but share the same chemical properties.