Particle models

• Isotopes are atoms with different masses but the same atomic number, meaning that they contain the same number of protons but differing amounts of neutrons.
• Atoms are neutral because they have equal numbers of positive charges (protons) and negative charges (electrons).
• The mass number is the total number of protons and neutrons.
• The mass number is equal to the sum of the numbers of protons and neutrons in an atom's nucleus.
• Atoms can be represented by their chemical symbol followed by the mass number (A) and then the atomic number (Z).
• Ions are charged particles formed when electrons are added or removed from atoms.
• Ions are charged particles formed when electrons are added or removed from atoms to achieve electrical neutrality.
• The mass number is the total number of protons and neutrons in an atom's nucleus.
• Ions are charged particles formed when an atom gains or loses electrons.