The atomic radii of the elements Na , Mg , Al , and Si are given in a random order as 118 pm , 143 pm , 160 pm , and 186 pm . Based on the periodic trend, which of the following represents the correct atomic radius of Al ?

Step-by-step solution

The given elements Na , Mg , Al , and Si belong to the third period of the periodic table. As we move from left to right across a period, the effective nuclear charge increases, which pulls the valence electrons closer to the nucleus. Consequently, the atomic radius decreases. The order of atomic radii for these elements is Na > Mg > Al > Si . Arranging the given values in decreasing order, we get 186 pm > 160 pm > 143 pm > 118 pm . Matching the elements with their corresponding radii: Na = 186 pm Mg = 160 pm Al =