Imagine you have a pile of apples. All look similar on the outside, but some are heavier than others due to thicker cores. This is similar to how isotopes work. Isotopes are versions of an element that have the same number of protons and electrons, but different numbers of neutrons. This makes some isotopes heavier than others. You've probably heard of carbon, a key element in our bodies and the world around us. But did you know that there are different isotopes of carbon, like carbon-12 and carbon-14? The number refers to how many protons and neutrons the isotope has. Carbon-14 is used in carbon dating to figure out the age of ancient artifacts! Isotopes aren't just for history, they're also important in medicine. For example, the isotope iodine-131 is used to treat certain types of thyroid cancer. Despite having different physical properties, isotopes of the same element behave the same chemically. However, some isotopes are stable, while others are radioactive and can decay over time, releasing energy in the process. Isn't it amazing how these tiny differences in atoms can have such a big impact on our world?