Periodic Table & Electrons

• Valence Electrons – electrons that are in the highest energy level of an atom.

• Example: Silicon

• 1s2 2s2 2p6 3s2 3p2

• 4 valence electrons…

Periodic Table & Electrons

• Representative elements (groups 1, 2, 13-18)

• Valence electrons = last number in the group number.

• Silicon Group 14 = 4 valence e- !

[http://academic.reed.edu/chemistry/roco/Lewis/images/periodic.gif]

Periodic Table & Electrons

• Noble gases have 8 valence electrons.

• This property makes them inert, or unreactive.

Neon = 1s22s22p6

Periodic Table & Electrons

• Other atoms form ions so that they have 8 electrons in the highest level.

[http://home.att.net/~cat6a/images/form_Na_ion.jpg]

[http://www.chemprofessor.com/ptable4.gif]

Ionization Energy• The energy needed to remove an

electron from an atom.

[http://www.iun.edu/~cpanhd/C101webnotes/modern-atomic-theory/images/ionization-energy.jpg]

[http://www.chemistry.ohio-state.edu/~grandinetti/teaching/Chem121/lectures/periodic%20trends/ionization_table.JPG]

Ionization Energy

• There are also 2nd Ionization Energies (remove 2nd electron) and 3rd Ionization Energies (remove 3rd electron).

• Pg. 180

Electronegativity

• The measurement of how much an atom “attracts” extra electrons.

Atomic Radius

• Distance from the center of an atom to the outermost electron.

• Ba, Ca, Sr

[http://wps.prenhall.com/wps/media/objects/602/616516/Media_Assets/Chapter05/Text_Images/FG05_20-07UN.JPG]

[http://images.encarta.msn.com/xrefmedia/aencmed/targets/illus/ilt/1e67a7ad.gif]