Transcript Organic Chemistry - Belle Vernon Area School District

ORGANIC
CHEMISTRY
Unit 1 – Atomic and
Molecular Structures
(Bonding Review)
The Atom
•2 Parts = Nucleus and electron (e-)cloud
•Nucleus – small, dense positively charged
region in the center of the atom (almost
all of its mass and none of its volume)
•e- Cloud – area surrounding the nucleus
where the e-s may be found
The Electron Cloud
•e- = negatively charged subatomic
particle found outside the nucleus
•e-’s are found in energy levels (shells )
from 1  ?
•shells are divided into sublevels
(subshells)
•shells contain orbitals (3-d region around
the nucleus where an e- may be found)
Electron Shells
Orbital Review
•SPDF – 2 e-s per orbital – with opposite
spins!
•s = 1, p = 3, d = 5, f = 7)
•Quantum Numbers (QN)
•Principal QN – n = E level
•Angular Momentum QN – l = shape
•Magnetic QN – m = orientation
•Spin QN – direction
Electron Configurations
•1. Pauli Exclusion Principle – no 2 e-‘s in
the same atom can have the same set of
4 quantum numbers
•The two e-‘s in an orbital have to have
opposite spins (
)
•2. Aufbau Principle – an e- will occupy the
lowest E orbital that can accept it
•3. Hund’s Rule – orbitals of equal E must
each have 1 e- before any can get 2
Electron Configurations
•Writing e- configurations : we use orbital
notation & e- config. Notation
•Principal QN = n 2n2 = # e-‘s in an e- shell
•Try the configurations for Na, O, Fe, and
Xe
•Try the orbital notation (orbital diagrams)
for the same elements listed above.
•Some exceptions in Transition, 4f, and 5f
Stability
•Atoms try to become stable by filling their
outer e- shell (8e-‘s)
•Octet = full shell of 8 e-‘s in the outer shell (s
& p orbitals)
•Full octet = Noble Gas Configuration
•Elements form compounds to gain octet
configurations
•Either transfer outer shell e-‘s to form ionic
bonds, or by sharing e-‘s to form covalent bonds
Noble Gas Notation
•Used for elements beyond K
•Practice the NGN for Ni, Sn, and Ba
Electron Dot Symbols (Lewis Structures)
•Show outer e-’s (s and p orbitals)
•Used to show chemical bonds
•Draw the next chart in your notebook and
fill in the blanks with the correct
information 
Lewis Structures
Group 1
Group 2
Group 3
Li•
•Be•
•
•B•
Lose 1 e-
Lose _ e-
Lose _ e-
+ 1 ion
__ ion
__ ion
Group 4
•
• C •
•
Group 5
Group 6
Group 7
Group 8
•
• N:
•
•
: O :
•
• •
: F :
•
••
: Ne :
••
Shares e- Gains _ e- Gains _ e- Gains _e- Does not
bond
__ ion
__ ion
__ ion
(Already
Stable)
Lewis Structures
Group 1
Group 2
Group 3
Li•
•Be•
•
•B•
Lose 1 e-
Lose 2 e-
Lose 3 e-
+ 1 ion
+ 2 ion
+ 3 ion
Group 4
•
• C •
•
Group 5
Group 6
Group 7
Group 8
•
• N:
•
•
: O :
•
• •
: F :
•
••
: Ne :
••
Shares e- Gains 3 e- Gains 2 e- Gains 1 e- Does not
bond
- 1 ion
- 2 ion
- 3 ion
(Already
Stable)
LS for Molecules
•Ionic Bonds are formed by metals
from Groups I, II, or III giving e-’s for
nonmetals from Groups VI, VII, or VII
• Try the LS and Orbital Diagrams for
K2S, Na3N, and CaF2
Bonding
•Gr I = bonds ns1
•Gr II = bonds *ns1np1
•Gr III = bonds * ns1np2
*=
•Gr IV = bonds * ns1np3
excited State
•Group V = bonds ns2np3
•Group VI = bonds ns2np4
n = E Level
•Group VII = bonds ns2np5 (Outer Shell)
Why promote an s e-?
Bonding Examples
•Try AlI3, Ca3N2, SrS
Covalent Bonding
•Covalent bonds are formed when Groups
IV – VII (and H) share outer shell e-s so
each atoms gets 8 e-s (except H can only
get 2 e-s)
•There are 4 kinds of covalent bonds (right
now = look at 3 of them)
•Remember diatomic elements NOAH
Covalent Bonding
•Single Covalent Bond – one pair of e-s
shared between 2 atoms
•F2
•Lewis Structure =
•Orbital Diag. =
Covalent Bonding
•Double Covalent Bond – two pairs of e-s
shared between 2 atoms
•O2
•Lewis Structure =
•Orbital Diag. =
Covalent Bonding
•Triple Covalent Bond – three e- pairs
shared between 2 atoms
•N2
•Lewis Structure =
•Orbital Diag. =
Covalent Bonding
•When Drawing Lewis Structures for
covalent structures, start with only 2
atoms and add alternatively as you need
them
•NCl3
Homework!
•Complete the following Lewis Structures
for Covalent Compounds for homework:
•H2O/ SBr2/ CBr4/ NP/ CO2/ N2O3/
Na2Te/ BaSe
Polyatomic Ions
•We can also take the same approach with
polyatomic ions
•Polyatomic Ion – covalently bonded group of
atoms that carries a net charge
•Negative polyatomic ions are formed by H +
ions leaving an oxyacid
•Oxyacid – an acidic substance that contains
oxygen
•Positive polyatomic ions are formed by H +
ions bonding coordinately to a neutral
molecule
In Class Assignment
•Do the Lewis Structures for the
following…
•[HSO4-/ SO4-2/ H2PO4-/ HPO4-2/ PO4-3/
HCO3-/ NO3-/ IO3-/ CO3-2/ NH4+/ PH4+/
H3S+/ H2Cl+/ H4I3+]
Last Covalent Bonding Type
•Coordinate Covalent Bond – a bond
where both shared e-s are from the same
species
• (bond between a Lewis acid and a Lewis
Base)