What makes one element different from another?

Elements are pure substances that cannot be broken down by chemical means. The atoms of each element have a number of protons that is unique to each element. The number of protons makes one atom different from another. read more

What makes one element different from another is the number of protons in the nucleus of its atoms. An atom is the smallest particle of an element that retains the properties of that element. Atoms contain protons and neutrons in the nucleus and electrons outside the nucleus. read more

Of these, 94 are known to occur in nature, while the others are man-made or synthetic elements. 80 elements have stable isotopes, while 38 are purely radioactive. The most abundant element in the universe is hydrogen. In the Earth (as a whole), it's iron. In the Earth's crust and human body, the most abundant element by mass is oxygen. read more