Transcript Periodic Table & Intro to Bonding

Bonding
Video 5.1
Types of Bonds
Octet Rule Review
Atoms bond with other atoms by sharing or
transferring electrons in order to achieve a stable
octet (8 valence electrons). Bonding creates stability!
released
*When bonds are formed energy is ___________.
absorbed
*When bonds are broken energy is ___________.
Ionic Bonds
O Transfer of
electrons from the
cation to the anion
(metal to
nonmetal).
O High melting point
and boiling point
O Mostly hard
crystalline solids
O Conduct as liquid
(either melted or
dissolved) due to
mobile ions.
Ionic Bonds
Sodium Chloride: NaCl
(table salt) properties:
O Hard
O Solid crystals
O High melting point,
forget boiling!
O Liquid phase conducts
(electrolytes are salts)
Metallic Bonds
O Metals only
O All metals lose their
O
O
O
O
O
valence electrons and
form a sea of electrons
High melting point and
boiling point
Insoluble in water
Always able to conduct
heat and electric due
to mobile electrons
Malleable
Ductile
Metallic Bonds
Copper (Cu) properties:
O Hard solid
O High melting point,
forget boiling!
O Malleable and
ductile
O Conductor
O Can’t dissolve
Metallic Bonds
Sea of electrons
Copper (I) ions
Copper (II) ions
Covalent Bonds (Molecular)
O Nonmetals only
O Share electrons
between atoms
O Low melting point
and boiling point
O Never conduct
heat or electricity
O Soft solid or gas
Covalent Bonds
Dextrose C6H12O6
(Sugar) properties:
O Soft
O Melts easily in sauce
pans for caramel
O Doesn’t conduct
(nonelectrolyte)
What type of bond is created?
1. Ca + O M+ NM = Ionic
M + NM = Ionic
2. K + Br
NM + NM = Covalent
3. S + Cl
4. I + S
NM + NM = Covalent
5. Li + Mg M + M = Metallic
M + NM = Ionic
6. Ba + S
Video 5.2
Ionic Compounds
Review: Find the ionic formula:
-
+
1. K + Br
+2
KBr
-
2. Mg + Cl
+
-2
+2
-2
3. Na + S
4. Ca + S
MgCl2
Na2S
CaS
Draw Lewis structures:
KBr
MgCl2
Na2S
CaS
Which subatomic particle is
involved in bonding?
Electrons only!
Geometry of ionic crystals
Ionic crystal
Ions
Video 5.3
Covalent Compounds
Covalent Lewis Structures
Rules: CCl4
1.
2.
3.
4.
5.
Add up all valence eC: 4 + 4Cl: 7 = 32 valence eDraw a skeletal structure
Cl
with bonds between
Cl—C—Cl
32-8=24
elements. Least frequent
Cl
element in the middle.
Subtract 2e- from total for
each bond drawn.
Draw in remaining e- to fill
each atom’s octet.
Evaluate: each atom
should have 8 e- only.
VSEPR
“Valence shell electron pair
repulsion” is a model for
molecules. Lone electron
pairs are repelled by one
another and should be
placed as far apart as
possible.
Geometry
1.
Linear: The molecule is on one plane (flat) such
as CO2 or H2.
2.
Bent: The molecule is bent at angle like H2O due
to unshared electrons and two bonding pairs on
the central atom.
Geometry
3.
Pyramidal: The molecule has a triangular shape
like NH3 due to a lone pair and three bonding
pairs on the central atom.
4.
Tetrahedral: The molecule has four
bonding pairs and no lone pairs on
the central atom like CH4.
Examples:
O Draw the following molecules and identify their
geometry:
PCl3
2. SiCl2H2
3. Br2
4. H2S
1.
pyramidal
tetrahedral
linear
bent
Video 5.4
Bond Polarity
Bond Polarity
The earth has two poles; North and South.
A magnet also has two poles.
Bonds may have two poles. This means
one element is charged different than the
other.
If a bond is polar, the two elements have
different electronegativities. The element
with a higher electronegativity will be more
negative.
Bond Polarity
Bond Polarity
Nonpolar Bond
Bond Polarity
Electronegativity
difference
Bond type
0-0.4
Nonpolar
0.5-1.0
Polar
1.1-2.0
Very Polar
2.0-4.0
Ionic
Ionic, polar or nonpolar?
1. C-Br
P
7. As-O
P
2. Na-S
I
8. N-O
P
3. C-C
NP
9. C-O
P
4. H-O
P
10.F-F
NP
5. K-O
I
11.S-C
NP
6. Be-B
I
12.N-H
P
Covalent Bonding
O If 2 atoms or more form a bond with the same
electronegativity the bonds are nonpolar and they
share e- equally. ( F-F )
O If there is an electronegativity difference between
bonded atoms, the bonds are polar and e- are pulled
toward the more electronegative atom. (H-F)
O If a bond is polar, the molecule will have a slightly
negative and slightly positive side, like 2 poles of a
magnet.
Video 5.5
Molecular Polarity
Molecular Polarity
O A polar molecule will
be asymmetrical.
O A nonpolar molecule
will have a
symmetrical shape or
all nonpolar bonds.
Molecular Polarity
Which are polar molecules? Show charges.
NP
+
P
+
NP
-
+
NP
-
-
+
+ -
+
P
-
-
Molecular Polarity
Water is polar, and like dissolves
like, so only polar molecules are
soluble in water. Polar
molecules are also attracted to
an electric field.
Molecular Polarity
O As you can see,
normally polar
molecules are
unaligned.
O When a electric source
comes by, the
molecules quickly align
themselves.
Video 5.6
IMF
IMF
O Intramolecular forces is another name for
bonds, that keep elements together in
compounds.
O Intermolecular forces of attraction are
weaker than bonds, but are responsible for
holding a substance together (multiple
molecules in a confined area).
IMF
O The stronger the IMF, the tighter the structure
(solid). The melting and boiling points will be high.
O The weaker the IMF, the looser the structure
(gas). The melting and boiling points will be low.
Dipole-Dipole
O Dipole-Dipole attractions are strong forces
between polar molecules. It is like static
holding the + and – charges together.
Hydrogen Bonding
A special case: Hydrogen Bonds are the
strongest bonds between Hydrogen and very
electronegative atoms such as F, O and N. (H
bonds are FON!) For example, H2O and HF,
due to their polarity, they will attract each
other.
London Dispersion Forces
(LDF)
The weakest attraction between nonpolar
molecules occur because electrons
temporarily shift creating a temporary + and
– charge. The more electrons the compound
has, the stronger the force is.
Summary
O From weak to strong:
O Nonpolar LDF
O Polar Dipole Dipole forces
O Hydrogen bonds
O Covalent Bonds
O Ionic Bonds
O Metallic Bonds
Class Notes
Show the individual and
bonded Lewis structures:
1.
Li and F
2.
Mg and O
3.
Be and S
4.
5.
6.
What did all the cations do?
What did all the anions do?
Which of the subatomic particles were changed and
how were they changed?
Type of Bonding?
1. CaCl2
8. CH4
15. NaOH
2. CO2
9. SO3
16. NO2
3. H2O
10. LiBr
17. AlPO4
4. BaSO4
11. MgO
18. FeCl3
5. K2O
12. NH4Cl
19. P2O5
6. NaF
13. HCl
20. N2O3
7. Na2CO3
14. KI