Calculating Atomic Mass:

The atomic mass of an element is the weighted average mass of all the isotopes of that element. Isotopes are atoms of the same element with different numbers of neutrons in their nucleus. To calculate the atomic mass, you need to consider the mass and abundance of each isotope.

Step-by-step process to calculate atomic mass:

1. Identify the isotopes: Determine the isotopes of the element and their respective abundances. Isotopes are usually denoted by their mass number, which is the sum of the protons and neutrons in the nucleus.

2. Assign mass: Determine the mass of each isotope. The mass of an isotope is given in atomic mass units (amu). One atomic mass unit is defined as 1/12th the mass of a carbon-12 atom.

3. Calculate weighted average: Multiply the mass of each isotope by its abundance (expressed as a decimal) and sum the results. This will give you the weighted average mass.

4. Convert to grams: The atomic mass is usually expressed in atomic mass units. If you want to convert it to grams, you can use the conversion factor: 1 amu = 1.66 x 10^-24 grams.

Example:

Let's take the element carbon as an example. Carbon has two stable isotopes: carbon-12 and carbon-13. The abundance of carbon-12 is about 98.89%, and the abundance of carbon-13 is about 1.11%.

1. Identify the isotopes:
- Carbon-12 (98.89% abundance)
- Carbon-13 (1.11% abundance)

2. Assign mass:
- Carbon-12 has a mass of 12 amu
- Carbon-13 has a mass of 13 amu

3. Calculate weighted average:
- (12 amu x 0.9889) + (13 amu x 0.0111) = 12.01 amu

4. Convert to grams:
- 12.01 amu = 12.01 x 1.66 x 10^-24 grams = 1.99 x 10^-22 grams

Therefore, the atomic mass of carbon is approximately 12.01 atomic mass units or 1.99 x 10^-22 grams.

Summary:

Calculating the atomic mass involves identifying the isotopes of an element, determining their masses and abundances, calculating the weighted average, and optionally converting it to grams. The atomic mass provides important information about the composition of an element and is used in various chemical calculations and equations.

To calculate the atomic mass, add up the mass of neutrons and protons.