VSEPR Model and the Resulting Shapes

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 0 Linear 1 or more 2 Bent

Trigonal Planar 3 0 Trigonal Pyramidal 3 1 Tetrahedral 4 0

VSEPR and Polarity

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? yes polar yes NONPOLAR • 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 __________________.

Let’s look at H2O dots asymmetrical polar like like polar nonpolar polar 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

VSEPR Model and the Resulting Shapes