Question

What is the atomic mass of iridium?

Answer 1

Hint: A single atom's atomic mass is simply its total mass, which is usually expressed in atomic mass units, or amu. An atom of carbon has six neutrons, carbon$ - 12$ , has an atomic mass of $12amu$ by definition.

Complete step-by-step answer:
Iridium is a chemical substance with atomic number $77$ and the symbol $Ir$ . Iridium is a platinum group transition metal that is very stiff, brittle, and silvery-white. It is the second-densest metal (after osmium) according to theoretical X-ray crystallography, with a density of $22.56g{(cm)^{ - 3}}$ .

There are two isotopes of iridium which are Iridium$ - 191$ and Iridium$ - 193$ .
Iridium$ - 191$ has a mass of $191.0amu$ and a $37.58$ percent of abundance. Iridium$ - 193$ has a mass of $193.0amu$ and a $62.42$ percent of abundance.

To find the atomic mass of iridium, we have to take the average mass of the individual isotopes.
Atomic mass of Iridium
$
   = \left[ {\left( {37.58\% \times 191} \right) + \left( {62.42\% \times 193} \right)} \right]amu \\
   = 192.25amu \\
 $

Therefore, the atomic mass of iridium is $192.25amu$.

Additional Information:Iridium is one among the rarest metals found in the Earth's crust, with just three tonnes produced per year. Iridium is the most corrosion-resistant metal material, resistant to air, water, salts, and acids, and is nearly as thick as the densest metal, osmium.

Note: The mass number is the sum of the number of protons and neutrons in the nucleus of any given isotope. This is because each proton and neutron have the same atomic mass unit $\left( {amu} \right)$ . The mass of an atom can be calculated by adding the sum of protons and neutrons and multiplying by $1amu$ .