Arrange the following element in increasing order of their atomic radii.
Cl, At, Br, I.
Answer
Cl, At, Br and I belong to same group of periodic table that is group 17. As we move down in a group, the atomic radii of elements increase due to increasing the number of shell. Thus, atomic radii of Cl, At, Br and I increase in the order: Cl < Br < I < At.
Identify the element with the following property and arrange them in increasing order of their reactivity:The metal which is an important constituent of limestone.
Arrange the following element in increasing order of their atomic radii.
Li, Be, F, N.
Answer
Li, Be, F and N belong to same period of modern periodic table. As we move left to right in the periodic table, the atomic radii of elements decreases due to high atomic charge and same number of shell. Thus the atomic radii of Li, Be, F and N increase in the order: F < N < Be < Li.
Identify the element with the following property and arrange them in increasing order of their reactivity:
An element which is a soft and reactive metal.
Compare the radii of two species X and Y. Give reasons for your answer.
Y has 12 protons and 10 electrons.
Answer
The available information makes it clear that:
Species Y with two electrons less (10) than the number of protons (12), is a divalent cation $y ^{2+}$ of species X . Therefore, the radius of species X is more as compared to that of $y ^{2+}$.
Note: The radius of cation is always less than that of atom while that of anion is more.
Compare the radii of two species X and Y. Give reasons for your answer.
X has 12 protons and 12 electrons.
Answer
The available information makes it clear that:Species X with equal number of protons (12) and electrons (12) is an atom. Therefore, the radius of species X is more as compared to that of $y^{2+}$.
Note: The radius of cation is always less than that of atom while that of anion is more.
Identify the element with the following property and arrange them in increasing order of their reactivity:The metal which exists in liquid state at room temperature.