VSEPR Model and the Resulting Shapes

VSEPR When atoms bond, every and ____ need their own space. As a result, they make a three dimensional molecular shape. This is the basis of the Valence Shell Electron Pair Repulsion (VSEPR) model. atom electron pair

VSEPR Shapes 1 N/A Linear 2 Linear 1 or more 2 Bent How many atoms are surrounding the central atom? Are there dots (lone pairs) on the central atom? VSEPR Shape (with Lone Pairs Shown) VSEPR Shape (without Lone Pairs Shown) Name of VSEPR Shape 1 N/A Linear 2 Linear 1 or more 2 Bent

Trigonal Planar 3 Trigonal Pyramidal 3 1 Tetrahedral 4 How many atoms are surrounding the central atom? Are there dots (lone pairs) on the central atom? VSEPR Shape (with Lone Pairs Shown) VSEPR Shape (without Lone Pairs Shown) Name of VSEPR Shape Trigonal Planar 3 Trigonal Pyramidal 3 1 Tetrahedral 4

VSEPR and Polarity

Since all atoms have different electronegativities, a “ Since all atoms have different electronegativities, a “ ” for the electrons in a bond begins when atoms bond. When an atom bonds with another one of itself (example F-F), the difference in electronegativity is . This is known as covalent or covalent bond. When an atom bonds with different atoms, they can be or _________ covalent bonds, depending on the differences in electronegativities. Tug of war zero nonpolar pure polar nonpolar

What happen when the electronegativity isn’t equal large When the difference in electronegativity is , an electron is and bonding results. When the difference in electronegativity is ______ ____________, the electrons are __________ ____________ and bonding results. transferred ionic very small (<0.5) shared nonpolar equally

moderate When the difference in electronegativity is , there is sharing. Resulting in a covalent. As a result, the electrons spend more time around the electronegative ( ) atom, which makes it slightly . The weaker atom becomes slightly . This results in the polar bond being a – two poles unequal polar more stronger negative positive dipole

Polarity of Molecules Overall, molecules can be or , depending on the results of the molecular “ .” If the VESPR shape makes it a molecule then the result is . If VESPR shape makes it a molecule then the result is . polar non-polar Tug of war symmetrical nonpolar asymmetrical polar

So, what does this mean to us? To determine if a molecule is polar or not, ask yourself: Are there dots on the central atom? If __________________ , it is automatically __________________. If not, then ask yourself: Are all the elements around the central atom the same (or are the two atoms the same in the case of the two atom linear molecules)? If __________________, It is __________________. yes polar yes NONPOLAR

Let’s look at H2O Water has _____________ which makes its shape __________________, so this would make water __________________.  Ability of a substance to dissolve is based on polarity … _____________ dissolves _____________. So, _____________ dissolves polar and _____________ dissolves non-polar. Water is polar, so it dissolves _____________ substances dots asymmetrical polar like like polar nonpolar polar