Final answer:
To find the number of protons in an atom, check the atomic number of the element on the periodic table. For neutral atoms, the number of protons is also equal to the number of electrons. To calculate neutrons, subtract the atomic number from the mass number.
Step-by-step explanation:
Finding the Number of Protons in an Atom
To determine the number of protons in an atom, you need to identify the atomic number of the element. The atomic number is unique to each element and is found on the periodic table. This number indicates the number of protons present in the nucleus of an atom of that element. For example, helium has an atomic number of 2, which means it has 2 protons in its nucleus. If an atom is neutral (meaning it has no net charge), this is also the same as the number of electrons.
Furthermore, the total number of protons and neutrons in an atom is known as the mass number. To calculate the number of neutrons, you subtract the number of protons (the atomic number) from the mass number. For instance, if an atom has a mass number of 40 and an atomic number (number of protons) of 19, it would have 21 neutrons (40 - 19 = 21).