Chemistry TEST 8

Valence Bond Theory

a model of chemical bonding that states that atoms fill their valence shells by filing vacancies in particular orbitals

Molecular Orbital Theory

The orbital of an atom are replaced by new orbitals when a molecule forms

What type of bonds make up triple bonds?

one sigma and two pi

For some molecules, no single Lewis structure can completely describe the distribution of electrons. The display of intermediate character within the bonds of much molecules called

Resonance

A sigma bonds is stronger than a pi bond

True

Some atoms are stable with LESS than a full octet of electrons when they form, but none ever have more than 8 electrons

False

Predict the shape of the molecule HCN

Linear

Predict the shape of the molecule H2CO

Trogonal Planar

Any molecule having a pyramidal or a bent shape will be polar

True

Sigma Bonds

overlap end to end, overlap located between the nuclei, strongest alone

Pi Bonds

overlap side to side, overlap located above and below the nuclei

Single bond

one sigma

Double Bond

one sigma and one pi

Triple Bond

one sigma and two pi

Molecular resonance

no single Lewis structure can completely describe electron distribution in resonance molecules

Octet Rule Expectation

the presence of an odd number of valence electrons, electron deficiency, hypervalent molecules

Free radicals

substances that have an odd number of valence electrons to share

VSEPR Theory

explains the shapes of molecules; determined by the number of atoms around the central atom and the bond atom

Tetrahedral

four regions of electrons, four atoms bonded to the central atom, 109.5 angle between bonds, nonpolar

Trigonal planar

Three region of electrons, three atoms bonded to the central atoms, 120 angle between bonds, non-polar

trigonal PYRAMIDAL

four regions of electrons, THREE bonded to the central atom, slightly less than 109.5 angle between bonds due to the one unbonded pair of electrons, polar

Linear

two regions of electrons, 120 angle between bonds

bent

either three or four regions of electrons, either 120 angles (three electron regions) or 109.5 angles (four electron regions), POLAR

Orbitals Hybridization

The form of a new orbital due to the overlapping of atomic orbitals

polar molecules

a molecule with both a positive end and a negative end due to the polar nature of its bonds and the shape of the molecule

greater distance+ more polar

True