Atoms and Isotopes

Atoms and Isotopes

1. Structure of the Atom

   • Contains a positive charged nucleus
     • Made up of protons and Neutrons
       • Surrounded by negatively charged electrons
         • Protons have an Electrical charge of +1, electrons have a charge of -1
     • An atom that looses one of its outer electrons becomes a positive ion
       • If it gains an extra electron it becomes a negative ion
   • Atoms have equal numbers of electrons and protons so they have no charge
   • The nucleus contains the most mass, but its radius is less than 1/10000 of the radius of the atom
   • The electrons are arranged at different distances from the nucleus in different energy levels
   • The energy of an electron may change when the atom emits or absorbs electromagnetic radation
     • Absorbing electromagnetic radiation moves electrons to a higher energy level further from the Nucleus
     • Electromagnetic radiation is emitted when an electron drops to a lower energy level

2. Isotopes

   • All atoms of a particular element have the same number of protons
     • The number of protons in an atom of an element is called the atomic number
   • The total number of protons and neutrons in an atom is called its mass number

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