Question

Density of which of the following elements is highest.
A) ${\text{Pt}}$
B) ${\text{Hg}}$
C) ${\text{Mn}}$
D) ${\text{Cu}}$

Answer 1

Hint:The density of an element is defined as mass divided by volume. Going from up to down in the group of periodic tables the volume doesn’t increase much. One can relate these concepts with the given option elements and find out density value.

Complete answer:
1) First of all we will learn how we can find out the density of an element by using its mass number and periodic table position.
2) The density is directly proportional to the mass of the element and indirectly proportional to the volume of the element.
3) Now when we go down the group in d-block the size of the elements doesn’t increase but the electrons get added in the shell itself. Due to the weak shielding of f-orbitals the size of the d-block elements doesn’t increase.
4) Now let's analyze the given elements one by one. The element ${\text{Pt}}$ is present far low in the d-block hence the volume of the element is lower than other elements. The platinum has a mass of ${\text{195 u}}$ and it is highest in all the given options elements. Hence, platinum has the highest density.
5) The elements ${\text{Mn}}$ and ${\text{Cu}}$ are present in a very early period in the d-block hence they have more volume and resulting in a lower density.
6) The element ${\text{Hg}}$ has mass numbers more than platinum but the volume also increases due to an increase in the size of the element due to more electrons. Hence, it will have less density than platinum.
Therefore, the density ${\text{Pt}}$ of the element is highest which shows option A as the correct choice.

Note:
The poor shielding of the f-orbitals which means the electrons are far from the nucleus, will result in an increase in the mass of the element but it doesn’t affect the volume of the element. As mass increases but volume remains the same the density of elements will also increase.