To calculate the number of electrons in an atom, you need to know its atomic number. The atomic number represents the number of protons in the nucleus of an atom, and in a neutral atom, it is also equal to the number of electrons.
Here's the process:
Identify the atomic number of the atom you're interested in. You can find this information on the periodic table of elements. The atomic number is usually displayed above or below the chemical symbol for the element.
The atomic number gives you the number of protons in the atom's nucleus, and in a neutral atom, the number of electrons is also equal to the atomic number. Therefore, you can directly use the atomic number as the number of electrons.
For example, let's consider the element carbon (C) with atomic number 6. This means that a neutral carbon atom has 6 electrons.
It's worth noting that in certain cases, such as ions or atoms with an electric charge, the number of electrons may be different from the atomic number. In these cases, additional information is required to determine the exact number of electrons.