Lewis Dot & VSPER

Octet Rule In bonding, atoms share or transfer electrons to attain the electron configuration of a noble gas (He-2 valence electrons all others 8 valence electrons).

Lewis Dot A Lewis Structure is a simplified model that represents the valence electrons of an atom. This model is helpful since only valence electrons are used for bonding molecules.

How to draw a Lewis Dot Diagram Write out atomic symbol  Si Determine the number of valence electrons (group number)4 Start on the right and draw electrons counter clockwise around atomic symbol REMEMBER: Lewis Dot Structures show only the valence electrons, not all of the electrons of an atom.

Practice with Lewis Dot Diagrams Br Al Ba

Tips & Tricks for Covalent Lewis Dot Diagrams Add up all the valence electrons Divide this number by 2 to get pairs of electrons This is how many lines (─) or pairs (∙∙) you have Try carbon in the middle first. If you don’t have a carbon pick the “single” atom to go in the middle. Exception: Hydrogen shouldn’t go in the middle If you have multiple “single” atoms pick the atom with closest to four valence electrons Check, is everybody “Happy”? Try satisfying all octets with single bonds IF that doesn’t work move on to double, then triple bonds.

Molecule Shapes Molecular Geometry: The arrangement of atoms within a given molecule. VSEPR: Valence Shell Electron Pair Repulsion Is based on simple electrostatic repulsions of electron pairs Assumption: Electrons in chemical bonds( single, double, or triple) and unshared electron pairs are negative centers that repel each other

VSEPR Shapes Shape Atoms Bonded Electron Regions Example Linear 2 Bent 3 or 4 Trigonal Planar 3 Trigonal Pyramidal 4 Tetrahedral