electrons in the highest occupied energy level always in the s and p orbitals

normally just a draw a circle to represent these two orbitals

determines the chemical properties of an element usually the only electrons used in chemical

bonds

http://wps.prenhall.com/wps/media/objects/476/488316/Instructor_Resources/Chapter_09/FG09_27-06un.JPG

http://jade.ccccd.edu/mweis/Images/Fireworks%20Drawings/2401%20related%20drawings/drawings%20in%20fireworks/body,%20cell,%20tissue/body_chem/chem_drw_atom_generic.png

electron dot structures/diagrams are used to show valence electrons each dot around the element symbol

represents a valence electron

B is 1s2 2s2 2p1; 2 is the outermost energy level it contains 3 valence electrons, 2 in the s

and 1 in the p Br is [Ar] 4s2 3d10 4p5

How many valence electrons are present?

http://images.google.com/imgres?imgurl=http://hyperphysics.phy-astr.gsu.edu/hbase/pertab/imgper/econfig.gif&imgrefurl=http://hyperphysics.phy-astr.gsu.edu/hbase/pertab/perlewis.html&h=267&w=512&sz=22&tbnid=__EXctBwlG0J:&tbnh=66&tbnw=128&hl=en&start=1&prev=/images%3Fq%3DElectron%2BDot%2BDiagrams%26svnum%3D10%26hl%3Den%26lr%3D

when forming compounds, atoms tend to achieve the electron configuration of a noble gas (ns2np6) this means they “want” their highest energy

level filled with 8 electrons the easiest way possible

atoms of metallic elements lose electrons producing cations (positive ions) Ca becomes Ca2+

atoms of nonmetallic elements gain electrons producing anions (negative ions) Cl becomes Cl1-

+ +- -

e-

  ...etc.

As it turns out, atoms bond together for a very simple reason: atoms like

to have full valence shells.

1+ 2+ 3-3+ 4+/- 2- 1- 0

for transitional metals, charges of cations may vary

iron can be Fe2+ or Fe3+

other elements fill some orbitals but don’t quite get a noble gas electron configuration

http://www.iun.edu/~cpanhd/C101webnotes/chemical-nomenclature/images/polyions.jpg

usually composed oppositely charged metallic cations and nonmetallic anions

form a compound with overall zero charge know as the rule of zero charge

+ cations

- anions

Na “gives” Cl one electron and now both atoms have a full valence shell (electron configuration of a noble gas)

shows the kinds and numbers of atoms in the lowest whole-number ratio of ions in the ionic compound Na 1+ + Cl 1- NaCl Ca 2+ + Cl 1- CaCl2

Mg 2+ + O 2- MgO

Mg and N? it takes two

nitrogens to combine with three magnesiums Mg3N2

magnesium nitride

Al and O

Na 1+ + F 1- NaF

high melting points can conduct electric currents when

melted or dissolved in water will shatter if impacted or crushed