Midterm Study Guide
• Chapter 4
o Naming compounds & writing formulas
▪ Become familiar with polyatomic ions
o Lewis symbols
▪ Diagrams that show bonding between atoms of a
molecule and the lone pairs that may exist in the
o Resonance—electron movement (generally from an electronegative atom)
▪ Way of describing delocalized e’s
o Elecronegativity, unequal sharing and polar bonds
▪ Ionic bonding
We also discuss several other topics like How long does it take to conduct down axons?
Usually one, two, or 3 e’s are transferred from one atom to another
▪ Covalent bonding
Sharing of electrons
Octet rule: Atoms lose, gain, or share electrons in order to have a full valence shell of 8 e’s
Formal charge: A formal charge is a comparison of electrons owned by an atom in a Lewis structure vs. The # of e’s possessed by the same atom in its unbound, free atomic state.
Lewis dot structures: diagrams that show bonding between atoms of a molecule and the lone pairs that may exist in the molecule. We also discuss several other topics like Which drugs are used for lethal injection?
We also discuss several other topics like What is the function of aggregate production?
FC=(# of valence e’s)-(# of electrons in a lone pair)+(1/2 of shared e’s)
We also discuss several other topics like The painting virgin and the child is made up of what?
If you want to learn more check out What is the function of hydrogen bond?
Complete the Lewis Dot Structure for HOCl
HOCl>all formal charges are zero
NO3—Draw the Lewis Dot Structure
o Determine v e’s in the molecule
V e’s 1
o Draw skeleton using only single bonds
o Start with electronegative atom first If you want to learn more check out Who organized the first convention on women's rights?
o Ask: Are all octets filled?
If not, fill remaining octets by making multiple bonds. (lone pair atom electroneg atom into bonding pair)
o Check formal charges
FC equ: 6-1-6=-1
• Chapter 4 (cont.)
o Lewis Dot Structures
o Formal charge of an atom
Specified FC equ=(# of valence e’s on atom)-(# of e’s in lone pairs[# of non-bonded e’s])-1/2(# of e’s shared in bonds)
▪ In general, atoms in the fourth period and beyond, higher d orbitals can be used to accommodate additional shared e’s.
▪ Main group elements that form more bonds than
predicted by the octet rule are called hypervalent
compounds, and have what is known as an ‘expanded
octet,’ meaning????more than 8 e’s around on atom.
▪ Atoms bond in such a way that each atom acquires 8 e’s in its outer shell.
▪ Shows valence electrons indication the bonding between atoms.
Draw the Lewis dot structure for the following compounds: BeF2 PBr5 BCl3 SI6 CCl4 BH2^- H2S
▪ Octet rule can be ‘expanded’ by some elements utilizing the d-orbitals found in the third principal energy level and beyond. Sulfur, phosphorous, silicon and chlorine are
common examples of elements that form expanded
FC—comparison of e’s and ‘owned’ by an atom in a Lewis structure vs. the number of e’s possessed by the same atom in its unbound, free atomic state
• Valence Shell electron pair repulsion Theory o E’s neg. charge (-) and they repel each other
o E’s are arranged about central atom in a way to minimize those repulsions.
Molecular geometry—describes the relative positions of atoms in a molecule.
Valence Theory and Hybrid Orbitals
???? A chemical bond forms when atomic orbitals of atoms overlap.
Atomic Orbital: an expected region of electron density around an atom based on a solution to the Schrodinger Wave function.
Hybridization: atomic orbitals produce hybrid orbitals.
The total # of orbitals available for forming
bonds does not change—a new set is simply
Linear sp hybrids: the two hybrid orbitals formed by the mixture of one s-orbital and one p orbital.
Trigonal sp^2 hybrids: the three hybrid orbitals formed by the mixture of one s and two p orbitals.
Tetrahedral sp^3 hybrids: the four hybrid orbitals formed by the
mixture of one s orbital three p orbitals.
Shortcut to determining hybridization of an atom in a molecule:
▪ Look @ the atom
▪ Count the # of atoms connected to the atom in question
(not bonds: ATOMS).
▪ Count the # of lone pairs attached to it
Add these together:
If it’s 4????sp^3
If it’s 3????sp^2
If it’s 2????sp
Compound bonds lone pairs geometry hybridization
NH3 3 1 tetrahedral sp^3 4
SO3 3 0 trigonal SP^2 3
CO2 2 0 linear sp 2
• Chapter 5
sp linear sp^3d Trigonal Bipyramidal sp^2 Trigonal Planar sp^3d^2 octahedral sp^3 Tetrahedral
Bent seesaw/distorted tetra T-shaped square pyramid Square Planar
For the following molecules:
o Determine a Lewis dot diagram
o Determine the molecular geometry at each central atom o Determine bond angles
Trigonal bipyramidal 72O