Atoms

• Atom


  Tiny particle that everything, living or non-living, is made up of
• Atom


  • Central nucleus surrounded by electrons orbiting in rings called shells
  • Nucleus made up of protons and neutrons
• Proton


  Particle in the nucleus with a positive charge
• Neutron


  Particle in the nucleus with no charge (neutral)
• Electron


  Particle orbiting the nucleus with a negative charge
• Protons and neutrons have a relative mass of 1, electrons have a mass 2000 times smaller
• Atoms have a radius of around 0.1 nanometers, but most of the atom is empty space
• The nucleus is 10,000 times smaller than the width of the atom
• Ion


  Atom that has lost or gained electrons, so the positive and negative charges no longer balance
• Types of ions

  • Negative ion (more electrons than protons)
  • Positive ion (more protons than electrons)
• Periodic table


  Table that represents different types of atoms, called elements
• Atomic number


  Number of protons in the atom, determines the element
• Mass number


  Total number of protons and neutrons in the atom
• The number of protons and electrons in an atom is always the same