Atomic Structure and Radioactivity

• The nucleus is the central part of an atom, containing protons and neutrons.
• Protons have a positive charge (+1), and are located in the nucleus.
• Neutrons are neutral (no charge) and are found in the nucleus.
• Electrons have a negative charge (-1), and are found in electron shells.
• Ions can be positively charged (cations) if they have lost one or more electrons, or negatively charged (anions) if they have gained one or more electrons.
• Atomic number (Proton number) = number of protons
• Nucleon number (Mass number) = number of protons + number of neutrons