The atomic number of an element represents the number of protons in the nucleus of an atom of that element. In a neutral atom, the number of protons is equal to the number of electrons surrounding the nucleus. Therefore, to calculate the number of protons and electrons from the atomic number, you simply use the atomic number itself.
For example, let's take the element carbon with an atomic number of 6. This means that a carbon atom has 6 protons in its nucleus. Since it is neutral, it also has 6 electrons orbiting the nucleus.
So, in general, if you know the atomic number of an element:
- The number of protons is equal to the atomic number.
- The number of electrons is also equal to the atomic number (in a neutral atom).
It's important to note that ions can have a different number of electrons than protons. In ions, the number of electrons can be calculated by considering the charge on the ion. For example, if you have a carbon ion with a +2 charge (C2+), it means it has lost two electrons, so the number of electrons would be 6 - 2 = 4.