Unit 8: Bonding and Molecular Geometry

Formal Charge

________- used to determine which structure is the most likely.

Bond Theory VSEPR Model

________- Predicts shapes of molecules by assuming that the valence e pairs are arranged as far from one another as possible (to minimize repulsion)

O3

Delocalized Bonding: Resonance- can represented by two different Lewis e- dot formulas or pair is shared (________)

Octet rule

________- tendency to have 8ei in outer shells (Its 2e- for H2)

Molecular Geometry

________ of an atom with 2 bonding pairs and 0 lone pairs- linear.

Lewis

________ structures- that allow us to predict many properties of molecules (Electron Dot Structure)

Electronegativity

________- ability of an atom to draw bonding electrons to itself, increases from lower- left to upper- right corner.

Polar Molecule

________ (Dipole)- exhibiting any asymmetry, having a nonzero dipole moment.

Dipole Moment

________- a measure of the degree of charge separation in a molecule.

Ionic Bond

________- when the difference in electronegativity exceeds about 1.8.

Molecular Geometry

________ of an atom with 3 bonding pairs and 2 lone pairs- T- Shaped.

Molecular Geometry

________ of an atom with 2 bonding pairs and 1 lone pair- bent or angular.

Molecular Geometry

________ of an atom with 4 bonding pairs and 0 lone pairs- tetrahedral.

Molecular Geometry

________ of an atom with 2 bonding pairs and 2 lone pairs- bent or angular.

Molecular Geometry

________ of an atom with 6 bonding pairs and 0 lone pairs- Octahedral.

Molecular Geometry

________ of an atom with 2 bonding pairs and 3 lone pairs- linear.

Molecular Geometry

________ of an atom with 5 bonding pairs and 1 lone pairs- Square Pyramidal.

Molecular Geometry

________ of an atom with 3 bonding pairs and 0 lone pairs- trigonal planar.

Molecular Geometry

________ of an atom with 3 bonding pairs and 1 lone pair- trigonal pyramidal.

Molecular Geometry

________ of an atom with 5 bonding pairs and 0 lone pairs- Trigonal bipyramindal.

Molecular Geometry

________ of an atom with 4 bonding pairs and 2 lone pairs- Square Planar.

Bonding

a chemical bond forms when the potential energy of the bonded atoms is less than the potential energy of the separate atoms

Lewis structures

that allow us to predict many properties of molecules (Electron Dot Structure)

Isoelectronic group of ions

ions that have the same number and configuration of electrons

Ionic Bonds

bond formed by electrostatic attraction between (+) and (-) ion

Covalent Bonds

Bond that share valence electrons, share sufficient number of electrons in order to achieve a noble gas electron configuration

Coordinate Covalent bond

bonds between atoms where both electrons are donated by one of the atoms

Double bond

two pairs of electrons are shared between atoms

Triple Bonds

three pairs of electrons are shared between atoms

Polar covalent bond

the bonding electrons spend more time near one of the two atoms

Nonpolar covalent bond

for alike atoms (as in H2) the bonding electrons are shared equally

Polar bond

shared not equally (HCl)

Electronegativity

ability of an atom to draw bonding electrons to itself, increases from lower-left to upper-right corner

Polarity of Bond

the absolute difference in electronegativity of two bonded atoms

Nonpolar Bond

when the difference in electronegativity is small

Polar Bond

when the difference in electronegativity is larger > 0.5

Ionic Bond

when the difference in electronegativity exceeds about 1.8

Expanded Octet Exception

the central atom has more tha n8 electrons (3rd period or greater)

Fewer then 8 Electrons Exception

the central atom does not need a full octet (very small atoms smaller than C)

Formal Charge

used to determine which structure is the most likely

Bond Theory VSEPR Model

Predicts shapes of molecules by assuming that the valence e pairs are arranged as far from one another as possible (to minimize repulsion)

electron pair arrangement steps

1. Draw Lewis structure 2. Determine how many electron pairs are around the central atom 3. Arrange electron pairs according to VSEPR 4. Obtain geometry from directions of bonding pairs

Arrangement of 2 electron pairs

linear (180 degrees)

Arrangement of 3 electron pairs

trigonal planar (120 degrees)

Arrangement of 4 electron pairs

tetrahedral (109.5 degrees)

Arrangement of 5 electron pairs

trigonal bipyramidal (90, 120 degrees)

Arrangement of 6 electron pairs

octahedral (90 degrees)

Molecular Geometry of an atom with 2 bonding pairs and 0 lone pairs

linear

Molecular Geometry of an atom with 3 bonding pairs and 0 lone pairs

trigonal planar

Molecular Geometry of an atom with 2 bonding pairs and 1 lone pair

bent or angular

Molecular Geometry of an atom with 4 bonding pairs and 0 lone pairs

tetrahedral

Molecular Geometry of an atom with 3 bonding pairs and 1 lone pair

trigonal pyramidal

Molecular Geometry of an atom with 2 bonding pairs and 2 lone pairs

bent or angular

Molecular Geometry of an atom with 4 bonding pairs and 1 lone pairs

Seesaw

Molecular Geometry of an atom with 3 bonding pairs and 2 lone pairs

T-Shaped

Molecular Geometry of an atom with 2 bonding pairs and 3 lone pairs

linear

Molecular Geometry of an atom with 6 bonding pairs and 0 lone pairs

Octahedral

Molecular Geometry of an atom with 5 bonding pairs and 1 lone pairs

Square Pyramidal

Molecular Geometry of an atom with 4 bonding pairs and 2 lone pairs

Square Planar

Dipole Moment

a measure of the degree of charge separation in a molecule

Nonpolar Molecule (Dipole)

perfectly symmetric, having a 0 dipole moment

Polar Molecule (Dipole)

exhibiting any asymmetry, having a nonzero dipole moment

Steps to drawing Lewis Structures

1. find total of all valence e- 2. arrange atoms radially with the least electronegative in the center placing one pair of e- per bond 3. distribute remaining electrons to electronegative atoms to satisfy octet rule 4. distribute any remaining electrons to center atom