
______________________that hold atoms together in compounds. The electrons involved in bonding are usually those in the ___________________(valence) shell.

Most elements in compounds want to gain
______________________ configuration. They will do so by either ______________________ or ______________________ electrons (______________________ compounds) or by
______________________ electrons (______________________ compounds)

Chemical bonds are classified into two types:

______________________ results from electrostatic attractions among ions; which are formed by the transfer of one or more electrons from one atom to another. (metals low χ with nonmetals high χ)

______________________ results from sharing one or more electron pairs between two atoms.
(nonmetals only similar χ )


Melting Pt

Solubility
◦ (polar solvents)

Solubility
◦ (nonpolar solvents)

Conductivity
◦ (molten & aqueous solutions)
Ionic Covalent

2 extremes in bonding
______________________ ______________________
◦ electrons equally shared by the atoms
______________________ ______________________
◦ electrons are completely lost or gained by one of the atoms most compounds fall somewhere
______________________ these two extremes


# of atoms in the molecule
◦ ______________________ = 1 atom
◦ ______________________ = 2 atoms
◦ ______________________ = 3 atoms
◦ ______________________ = many
Ex. He
Ex. O
2
Ex. O
3
Ex. H
2
SO
4 or S
8


______________________ : the mlcl is composed of only 1 kind of atom: O
2,
H
2, more than 1 kind of atom: H
P
2
4
______________________ : the mlcl is made up of
O

.
H or Lewis dot formulas, a convenient bookkeeping method for ______________________
______________________ (electrons that are transferred or involved in chemical bonding)
Only the electrons in the outermost s and p orbitals are shown as dots.
..
H e
.
..
..
..
..
.
.
..
..
.
.
.
..
..
.
.

elements in the same group have same Lewis dot structures
.
.
Li & Na
.
..
..
.
.
.
..
.
.
..
.
For groups ______________________ , the group number equals the # of ______________________ electrons
Valence electrons determine the chemical and physical properties of the elements as well as the kinds of ______________________ they form.

______________________ react with ______________________ to form ______________________ compounds
______________________ or positive (+) ions (metals)
◦ atoms have lost 1 or more electrons
______________________ or negative (-) ions
(nonmetals)
◦ atoms have gained 1 or more electrons


(s)

2(g)

(s)

o
We can use Lewis formulas to represent the
______________________ atoms and the ______________ they form.
..
Li + F
.
Li
+ [ ]

underlying reasons for LiF formation
1s 2s 2p
Li 
F  becomes
Li +
F -

 [___]
[___]

Li + ions contain two electrons
◦ same number as helium
F ions contain ten electrons
◦ same number as neon
Li + ions are isoelectronic with ______________________
F ions are isoelectronic with ______________________
species contain the _______________ number of electrons.
cations become gas isoelectronic with ______________________ noble anions become gas isoelectronic with ______________________ noble

IIA metals with VIIA nonmetals, mostly
_________________ compounds ~ exceptions - BeCl
BeBr
2
, BeI
2 these are covalent compounds
2
,
Be(s) + F happening
2
(g)  BeF
2
(s) electronically this is
Be
..
..
. F
..
..
..
Be
2+
2
.
.
..
..
.
.
similarly for all of the IIA & VIIA
M(s) + X
2
 M 2+ X
2
-

IA + VIIA
IIA + VIIA
IIIA + VIIA
IA + VIA
IIA + VIA
IIIA + VIA
MX
MX
2
MX
3
M
2
X
MX
M
2
X
3

IA + VA
IIA + VA
IIIA + VA
M
3
X
M
3
X
2
MX
H forms ionic compounds with IA and
IIA metals
LiH, KH, CaH
2
, BaH
2,
, etc.
other H compounds are covalent

______________________ - the energy needed to separate oppositely charged ions.
The ______________________ the lattice energy, the
______________________ the ionic bond. The stronger the ionic bond the ______________________ in water at a given temperature, since the ions must ___________________________________ from one another and attach to water in order to dissolve.


  
2



~ ions with high (big)charges =
______________________
~ ions with small (large) charges =
______________________

(From Ch. 6)
E = k
Energy = lattice energy ,
Q
1
Q
2
= charge of positive ion
= charge of negative ion r = bond length, the distance between the nuclei of the 2 ions – can also be ______________________ by the Period.



For r (U se the Period of the element that is
______________________ with the ion!
Na is in Period 3 and has 3 occupied energy levels. Na + has lost an electron. It has 10 electrons and is isoelectronic with Ne in
Period 2. Na + has only 2 occupied energy levels.
)

arrange these compounds in order of increasing attractions among ions
KCl, Al
2
O
3
, CaO

1. Which has a stronger ionic bond, NaCl or
KCl? Explain why.
The lattice energy of __________________________________ , so this is the stronger ionic bond. Both have an electron charge of -1 and an effective nuclear charge of 1. But the valence electrons of ___ are in the ___ energy level, leading to a shorter bond length (measured as distance between ionic nuclei) and a stronger ionic bond than ___.

2. Which has a stronger ionic bond, NaCl or
AlCl
3
? Explain why.
The _________________ has a stronger ionic bond.
Both have the same -1 charge for the chloride ion, and both Na + and Al +3 are isoelectronic with Ne and therefore have 2 occupied energy levels. But the higher positive charge of the
______________________ leads to a stronger lattice energy and a stronger ionic bond.

3. Which is more soluble in 80° C water, NaCl or
KCl? Explain why
You can dissolve more grams of ____ in 100 grams of 80° C water since it has a
______________________ ______________________ which requires less energy to separate/dissociate the ions from one another and allow them to attach to the polar water molecules.

4. Which is more soluble in 80° C water, NaCl or
AlCl
3
? Explain why
_____is more soluble in 80° C water since it has a
______________________ ______________________ which requires less energy to ______________________
__________________ the ions from one another and allow them to attach to the polar water molecules.

5. Why is Na
2
Al
2
O
3 is not
O considered soluble in water while
Q
2 for oxygen is the same for both compounds, a
-2. Radius of oxygen is the same for both, and
Na + and Al +3 are isoelectronic. So the larger Q
1 charge makes the ______________________ of the
______________________ greater, and since the ions stay bonded to one another it will not dissociate and dissolve.

extended three dimensional arrays of oppositely charged ions
______________________ ________________ because coulomb force is strong

covalent bonds formed when atoms share electrons share 2 electrons ________________ covalent bond share 4 electrons ________________ covalent bond share 6 electrons ________________ covalent bond attraction is electrostatic in nature
◦ lower potential energy when bonded


Covalent bonding may be explained by 2 different theories
◦ ________________________________________________ : each atom has electrons in atomic orbitals which overlap to form bonds (Ch. 8)
◦ ________________________________________________ : the electrons belong to the molecule as a whole and are in molecular orbitals instead of belonging to each atom
(Ch. 9)


The element needing the most electrons to fill its octet is usually the central atom

The most symmetrical skeleton is usually correct

Halogens and H always share one electron to complete outer shell

In ternary acids, H are bonded to O (ternary acids are oxy-acids: they contain H, O, and another nonmetal)


Carbon always obeys the octet rule

Carbon rarely has lone pairs of electrons.
Exception: If it’s at the end of a molecule or ion. Ex. CN , CO, CNO

When forming multiple bonds between atoms, both atoms donate the same number of electrons


Oxygen atoms normally bond to other nonmetals, not to each other

Oxygen can do several things depending on the mlcl.
◦ Single bond by sharing an electron
◦ Single bond by accepting 2 electrons from another atom and not sharing at all
◦ Double bonds by sharing 2 of its electrons

___________________________ : diatomic molecules
◦ hydrogen, H
2 or H H
◦ fluorine, F
2 .
.
..
F .
.
..
F
..
..
.
.
or
.
.
..
..
F F .
.
◦ nitrogen, N
2 ·
·
N
·
· ·
·
·
·
N
·
· or
·
·
N N
·
·
________________ covalent bonds - electrons are shared equally symmetrical charge distribution must be the ________________________ to share exactly equally

Lewis dot representation
H
2 molecule formation
H.
+
H .
H H or H
2

___________________________: diatomic molecules hydrogen halides
◦ hydrogen fluoride,
HF
◦ hydrogen chloride,
HCl
◦ hydrogen bromide,
HBr
··
H F
··
·
·
··
H Cl
··
·
· or or
··
H F
··
·
·
··
H Cl
··
·
·
··
H Br
··
·
· or
··
H Br
··
·
·

________________________________ bonds - unequally shared electrons
• ______________________________ charge distribution
• different ________________________________
Some bonds are ________________ , Ex. HF
H F
Electroneg
Difference ativities  
1.9

1.9
very polar bond

Electron density map of
HF
◦ blue areas - low electron density
◦ red areas - high electron density polar molecules have
________________ of centers of negative and positive charge

Some bonds are only __________________________ , ex. HI
H I
Electroneg
Difference ativities  

0.4
slightly
0.4
polar bond

Electron density map of
HI
◦ blue areas - low electron density
◦ red areas - high electron density notice that the charge separation is not as
________________ as for HF
◦ HI is only slightly polar

________________________________ elements achieve noble gas configurations in most of their compounds.
Lewis dot formulas are based on the
________________ .

H needs two electrons to have Helium's noble gas configuration, everything else wants 8

water, H
2
O ammonia molecule , NH
3 ammonium ion , NH
4
+ hydrogen cyanide, HCN sulfite ion, SO
3
2-


Two or more Lewis dot diagrams are needed to describe the bonding in a molecule or ion.

LDD for sulfur trioxide, SO
3

three possible structures for SO
3 invoke resonance
◦ Double-headed arrows are used to indicate resonance formulas.

flaw in our representations of molecules no single or double bonds in SO
3 all bonds are the same length best picture


The concept of formal charges helps us choose the correct Lewis structure for a molecule. If a ________________________________ has a high formal charge it’s not a very good one.

Formal charge = group # - e you can assign to that atom
Or F.C. = (valence e ) – (# of bonds + # of unshared e ) pg 289

________________________________ (σ) : result of head-on
(end to end overlap, there is a free rotation around σ bonds.
________________ (π) : result of side-on overlap of p orbitals. There is no free rotation around a π bond. The side –on overlap locks the molecule into place.
All ________________ bonds are sigma bonds: 1σ bond
All ________________ bonds: 1 σ bond, 1 π bond
All ________________ bonds: 1 σ bond, 2 π bonds

 species in which the central element must have a share of more or less than 8 valence electrons to accommodate all substituents
 compounds of the d- and f-transition metals
In cases where the octet rule does not apply, the elements attached to the central atom nearly always attain noble gas configurations.
◦ ________________________________________________


Write LDD for BBr
3

Write LDD for AsF
5

Write LDD for XeF
4

As we all know, in the wintertime we are more likely to get shocked when we walk across carpet and touch the door knob. Here’s another experiment to perform. Turn on a water faucet until you have a continuous but small stream of water coming from the faucet. Brush your hair vigorously then hold the brush near the stream of water. You will notice that the stream bends towards the brush. Why does the water bend?
On a “infomercial” it claimed that placing a small horseshoe magnet over the fuel intake line to your car’s carburetor would increase fuel mileage by 50%.
The reason given for the mileage increase was that
“the magnet aligned the molecules causing them to burn more efficiently.” Will this work? Should you buy this product?