Subatomic Particles

Ever wondered what makes up the stuff around you? Atoms are the tiny building blocks of matter, and they're made of even smaller parts called subatomic particles. An atom is the smallest unit that still maintains its elemental properties.

The three fundamental subatomic particles are protons, neutrons, and electrons. Protons and neutrons live together in the nucleus (the atom's center), and both have approximately the same mass. Electrons orbit around the nucleus. Protons have a positive charge, electrons have a negative charge (equal but opposite to protons), and neutrons have no charge at all.

Normal atoms are neutral because they have equal numbers of protons and electrons, balancing the charges. When atoms gain or lose electrons, they become charged particles called ions. Losing electrons creates a positive ion, while gaining electrons makes a negative ion.

Quick Tip: Remember the relationship between numbers: atomic number = number of protons, mass number = protons + neutrons, and the number of neutrons = mass number - atomic number.

On the periodic table, each element shows its atomic number above its symbol and its atomic mass below. The mass number tells you the total number of protons and neutrons added together. If you need to find the number of electrons, just remember that electrons = protons - charge.