Atoms

• Atoms are made up of tiny particles called protons, neutrons, and electrons
• The basic structure of an atom consists of a central nucleus surrounded by electrons in shells
• Protons and neutrons are in the nucleus, with protons having a positive charge and neutrons being neutral
• Electrons have a negative charge and orbit around the nucleus in shells
• The mass of protons and neutrons is the same, with a relative mass of one, while electrons are much smaller with a mass 2000 times smaller
• An atom is neutral when the number of protons equals the number of electrons
• Atoms can lose or gain electrons, becoming charged ions
• The atomic number of an element tells us the number of protons in its atoms
• The number of neutrons in an atom can be calculated by subtracting the atomic number from the mass number