Atomic Structure & Periodic Table

• Ion


  A charged particle, could be a single atom or a group of atoms
• Formation of ions


  1. Atoms gain or lose electrons

  2. To have a full outer shell

  3. For stability
• Group number


  Tells us how many electrons the atoms of that group have in the outermost shell
• Atoms need to lose or gain electrons


  To become stable
• Losing and gaining electrons

  Requires energy
• Group 1 elements (alkaline metals)


  • Only have to lose 1 electron to have a full outer shell
  • Easily lose that electron to become 1+ ions
• Group 2 elements


  • Can easily lose 2 electrons to become 2+ ions
• Group 6 elements


  • Gain 2 electrons to become 2- ions
• Group 7 elements


  • Have to gain 1 electron
• Groups 3-5 elements


  • Would have to lose or gain 3-4 electrons, which requires a lot of energy, so they don't form ions often
• Equation for ion formation


  1. Atom goes to form ion + electron (if losing electrons)

  2. Atom + electron goes to form ion (if gaining electrons)
• Everything whether it's living, non-living or even a cell itself is made up of lots of tiny particles which we call atoms
• A single cell probably contains more than 100 trillion atoms
• Atom


  Basic structure is a central nucleus surrounded by electrons which orbit around the nucleus in rings that we call shells
• Particles that make up the nucleus

  • Protons
  • Neutrons
• Protons and neutrons


  • Have the same mass, with a relative mass of 1
  • Protons have a positive charge of 1+
  • Neutrons have no charge (are neutral)
• Electrons


  • Have a mass 2000 times smaller than protons and neutrons
  • Have a negative charge of 1-
• The size of an atom depends on which element it is
• Atoms have a radius of around 0.1 nanometers
• Most of an atom is actually empty space
• The nucleus is 10,000 times smaller than the width of the atom
• Electrons are even smaller than the nucleus and would be too small to see in the atom diagram
• Periodic table


  Each box represents a different type of atom, which we call an element
• Nuclear symbol


  Provides information about the element, including the elemental symbol, atomic number, and mass number
• The atomic number tells us the number of protons (and electrons) in the atom
• The mass number tells us the total number of protons and neutrons in the atom
• The number of neutrons in an atom is not always the same as the number of protons
• Atom


  Central nucleus comprising protons and neutrons, with electrons orbiting the nucleus
• Protons


  Determine which element the atom is
• Hydrogen


  • Smallest element, with 1 proton and 1 electron
• Elements


  • Around 100 different elements
• Periodic table


  Organizes elements, each box represents a different element
• Nuclear symbol


  Represents an element
• Atomic number


  Unique number representing the number of protons in the element
• Atoms with the same number of protons are the same element
• Isotopes


  Different forms of the same element that have the same number of protons but different number of neutrons
• Relative atomic mass


  Average mass of all the isotopes that make up a particular element
• Calculating relative atomic mass

  Multiply each isotope's abundance by its mass, sum these, then divide by the sum of all the abundances