All atoms of a particular element have the same atomic number. This means that they all have the same number of protons. But sometimes you can find heavy atoms of a particular element. These atoms have a higher mass number. The mass number is equal to the number of protons plus the number of neutrons. We can ignore the electrons as their mass is so tiny. If the number of protons always stays the same in a particular element and we ignore the mass of electrons, it must mean the number of neutrons is causing the difference in mass. Atons are the same element with a different mass number, I known as isotopes. They are defined as atoms of an element which have the same number of protons that are different number of neutrons. If we look at carbon and nitrogen, are they isotopes? They have different mass numbers, but they also have a different number of protons. Therefore, they are not isotopes. They are completely different elements. Different isotopes of elements do not have separate positions on the periodic table. They occupy the same spot because they have the same number of protons. What's about carbon 12 and carbon 14? Both carbon 12 and carbon 14 have the same atomic number, which means they have the same number of protons, but they have different masses. Carbon 12 has a mass of 12 and 6 protons. Remember, mass number equals protons plus neutrons. So we can rearrange this formula to give us neutrons equals mass number minus protons. 12 minus 6 equals 6. Therefore, it has 6 neutrons. Carbon 14 has a mass of 14, but it still only has 6 protons. Mass number equals protons plus neutrons. Rearrange neutrons equals mass number minus protons. 14 minus 6 equals 8. Therefore, carbon 14 has 8 neutrons. Carbon 12 and carbon 14 are not the only examples of isotopes. There are many more, such as hydrogen, titerium, and trotarium, and chlorine, density, and chlorine, density, and chlorine, density, and chlorine. Isotopes only differ in the number of neutrons and their mass. Their chemical properties are exactly the same, because neutrons have no effect on an elements chemical behavior. This is controlled by electrons, which we will discuss in another video. So isotopes atoms are the same element with the same number of protons, but a different number of neutrons. They have different masses, but their chemical properties are exactly the same. So isotopes are the same element with the same number of protons. They have different particles, but they are the same element with the same number of protons. They have different particles, but they are the same element with the same number of protons. They have different particles, but they are the same element with the same number of protons. They have different particles, but they are the same element with the same number of protons. They have different particles, but they are the same element with the same number of protons. They have different particles, but they are the same element with the same number of protons.