The Periodic Law

Dmitri Mendeleev - discovered that when placed in order of their atomic mass, elements show a repeating pattern of properties. Atomic radius Ionization energy Electronegativity

Fr P Atomic Radius - The size of the atom. Ba Au Pb K Cu Sn Cl He F I N Mg Kr

Atomic Radius - The size of the atom. Group Trend: Atoms get bigger moving down the periodic table. More energy levels = Electrons are further from the nucleus = Bigger atom

Atomic Radius - The size of the atom. Period Trend: Atoms get smaller moving across the periodic table. e e e e e e e e e e e e e e e e e There are more protons making a stronger nucleus attracting valence electrons that are at the same distance in the same outer energy level.

Atomic Radius - The size of the atom. Period Trend: Atoms get smaller moving across the periodic table. There are more protons making a stronger nucleus attracting valence electrons that are at the same outer energy level. e e e e e e e e e e e e e e e e e Which element is the biggest? Fr Which element is the smallest? He

Atomic Radius Trend Largest atom Smallest atom Increasing size He

Ionization Energy - The energy needed to remove a valence electron from an atom to form an ion. e e e e e e e e e e e e e e e e e

Why do you think it is so hard to remove electrons from noble gases? Lithium Sodium Cesium Potassium RubidiumFrancium Why is it so easy to remove electrons from alkali metals?

Ionization Energy - The energy needed to remove a valence electron from an atom to form an ion. Group Trend: The larger the atom, the less the attraction between valence electrons and protons in the nucleus making it easier to remove a valence electron.

Ionization Energy - The energy needed to remove a valence electron from an atom to form an ion. Increasing Ionization Energy Decreasing Ionization Energy Period Trend: The more protons an atom has, the stronger its pull on those valence electrons. (i.e. more energy needed to make an ion)

Ionization Energy Trend Increasing Ionization Energy Increasing Ionization Energy

Electronegativity – How strongly an atom attracts valence electrons in a bonding situation. e e e e e e e e e e Na e e e e e e e e e e e e e e e e e e Cl

Fr Electronegativity – How strongly an atom attracts valence electrons in a bond. RbK Na Li F Br Cl Cs At I electronegativity Where are the noble gases on this chart?

Group Trend: The smaller the atom, the greater the attraction between the protons in the nucleus and the valence electrons. (i.e. making it more electronegative) Electronegativity – How strongly an atom attracts valence electrons in a bond

Period Trend: The more protons an atom has, the stronger its pull on those valence electrons. (i.e. more electronegative) Electronegativity – How strongly an atom attracts valence electrons in a bond.

Increasing Electronegativity Decreasing Electro- negativity Electronegativity – How strongly an atom attracts electrons in a bond. X X X X X X

Trend in Electronegativity Increasing Electronegativity Increasing Electronegativity

Increasing Electronegativity Decreasing atomic size Increasing Ionization Energy Decreasing Ionization Energy Decreasing Electro-negativity Increasing atomic size SUMMARY

Atomic Radius Trend Largest atom Smallest atom Increasing size He

Ionization Energy Trend Increasing Ionization Energy Increasing Ionization Energy

Trend in Electronegativity Increasing Electronegativity Increasing Electronegativity