Download Chemical bonding

Chemical bonding
• You should already know:
– how to determine valence electrons
– what kind of elements make up covalent
and ionic bonds
– which type of bond are electrons shared
and which type of bond are electrons
transferred
– which elements gain electrons and which
lose electrons
Chemical bonding
• The valence shell becomes stable with 8
electrons except H and He (2 e-)
• The goal to achieve a full outer shell
drives the formation of bonds between
atoms
• Atoms with full valence shells have
filled s and p orbitals
Draw a Bohr
diagram for Ne
Write the
Draw a Lewis
electron
Dot diagram for
configuration for Ne
Ne; Highlight the
valence shell
configuration
Draw a Bohr
diagram for Ne
Write the
Draw a Lewis
electron
Dot diagram for
configuration for Ne
Ne; Highlight the
valence shell
configuration
2
2
1s 2s 2p
6
Ne
Lewis Structures-Covalent
N
O
N
B
O
N
D
I
N
G
P
A
I
R
S
BONDING
ELECTRONS
N
O
N
B
O
N
D
I
N
G
P
A
I
R
S
Lewis Structures-covalent
SHARED BONDING
ELECTRONS (are attracted
to both nuclei)
Lewis Structures-covalent
MOLECULES ARE USUALLY DRAWN THIS WAY;
THE LINE REPRESENTS THE SHARED PAIR OF
ELECTRONS IN A COVALENT BOND
Lewis Structures-covalent
SOME BOOKS OMIT THE
NONBONDING ELECTRONS
FOR SIMPLICITY
Draw Lewis Structures for the
following Covalent Compounds
Phosphorus + chlorine
P +
Cl
Phosphorus + chlorine
Cl
P
Cl
Cl
Oxygen and chlorine
Hydrogen and bromine
Hydrogen and oxygen
Hydrogen and chlorine
Carbon and fluorine
Hydrogen and carbon
Sulfur and oxygen
Silicon and fluorine
Sulfur and bromine
Lewis Structure-ionic compounds
X
Na +
Cl
+
Na
Cl
X
KCl
x
K
+
K
+
Cl
Cl
x
-
MgF2
2+
Mg
x
Mg x
x
F
+
F
-
x
F
AlF3
Na3N
MgO
Al2O3
LiBr
BaCl2
BONDING REACTIONS
WORKSHEET
Indicate Ionic or Covalent then
draw the Lewis Structure for each
1) Sodium and chlorine
2) Potassium and fluorine
3)Lithium and sulfur
4) Carbon and hydrogen
5) Beryllium and sulfur
6) Magnesium and nitrogen
7) Sulfur and fluorine
8) Aluminum and nitrogen
9) Carbon and chlorine
10) Carbon and fluorine
11) Sulfur and oxygen
12) Sulfur and hydrogen
13) Calcium and chlorine
14) Magnesium and phosphorus
15) Phosphorus and hydrogen
16) Challenge. Draw a Lewis
structure with two carbons and six
hydrogens
Guidelines for Lewis Structures
• The lesser amount of an element
gets placed in the middle of the
molecule (everything bonds to it)
• Hydrogen NEVER gets placed in
the middle
Guidelines for Lewis Structures
• Carbon is always placed in the
middle of the molecule (multiple
carbons are bonded together in a
chain)
Some common elements and their
number of bonds
• Hydrogen only produces one bond
• Oxygen produces 2 bonds (group
16)
• Carbon must have four bonds
(group14)
• Nitrogen must have 3 bonds (gr. 15)
Some common elements and their
number of bonds
• In general, one can use
similarities found in groups to
determine number of bonds
• You also can draw an elements
electron-dot structure to
determine number of bonds
H2O
CH4
PCl3
NH3
CH3NH2
HBr
H2Se
Cl2
N2H4
CH3OH
CHEMICAL REACTIONS
• A physical change does not
change the substance
• A chemical change (AKA
chemical reaction) does change
the substance
• Chemical changes are
accompanied by physical
changes
Processes that are physical changes
• Evaporation
• Condensation
• Melting
• Freezing
• boiling
CHEMICAL REACTIONS
happen around you everyday…
• RXNs can be used to heat a
home, power a car, manufacture
fabrics for clothing, make
medicines, and produce paints
and dyes in your favorite colors
• RXNs provide NRG for walking,
running, working, and thinking
Signs of a Chemical Reaction
None of the clues alone prove a
RXN has occurred because some
physical changes such as boiling
involve one or more of these
signs.
1)
2)
3)
4)
5)
Signs of a Chemical Reaction
Color changes
precipitation of a solid
Production of sound
odor changes
gas release
Signs of a Chemical Reaction
6) release of heat
7) release of light
8) Absorption or release of electrical
energy
9) Reduction or increase in
temperature
A chemical analysis that
shows the formation of a new
substance would be good lab
evidence that new products
were formed
Chemical Equations
• Any substance that undergoes a
reaction is called a REACTANT
• When reactants undergo a
chemical change, each new
substance formed is called a
PRODUCT
Chemical Equations Examples
Molecules in wood + oxygen
NRG + water + carbon dioxide
In your body:
Glucose + oxygen
NRG + water + carbon dioxide
Signs of a chemical reaction don’t
completely describe what
happens during a RXN
Chemists represent the changes
taking place in a reaction by
writing equations
WORD EQUATIONS
Acetic Acid + sodium hydrogen
carbonate
sodium acetate + water +
carbon dioxide
RED= REACTANTS
BLUE= PRODUCTS
= YIELDS/PRODUCES
CHEMICAL EQUATIONS
HC2H3O2 + NaHCO3
NaC2H3O2 + H2O + CO2
Be examining a chemical
equation, you can determine
exactly what elements make up
the substances that react and
form.
Physical State
HC2H3O2 (aq) + NaHCO3 (s)
NaC2H3O2 (aq) + H2O (l) + CO2 (g)
Symbols in parentheses are put
after the formulas to indicate the
state of the substance.
Symbol Meaning
Produces or yields
Reversible RXN
Heat
Reactants are heated, temperature not
specified
(s), (g), Symbols for solid, gas, liquid
(l),
(aq)
Pd
Substance dissolved in water
Chemical formula of a catalyst; a
substance added to speed up a RXN
NRG and chemical equations
• Noticeable amounts of energy
are absorbed or released during
a chemical reaction.
• If NRG is absorbed in the RXN,
it is endothermic
• If NRG is released in the RXN, it
is exothermic
NRG and chemical equations
2H2O (l) + NRG
2H2(g) + O2(g)
• When NRG is absorbed, NRG is
written as a reactant
NRG and chemical equations
CH4 (g) + 2O2(g)
CO2(g) + 2H2O(g) + NRG
When energy is released, NRG is
written as a product
SOME FORMS OF
ENERGY ARE LIGHT,
HEAT, SOUND,
ELECTRICAL
Once you finish the
notes complete the
sheets in baskets #6
&#7( Concept Review:
Describing Chemical
Equations WS)
Balancing Chemical Equations
http://misterguch.
brinkster.net/eqnb
alance.html
Law of Conservation of Mass
Matter is
During a
neither created
chemical
nor destroyed
reaction, atoms
during a
are
rearranged,
chemical
not
destroyed.
reaction.
The mass of the stuff that you make in a
chemical reaction is the same as the mass of
the stuff that you start with). This is called
the Law of Conservation of Mass
Balancing Chemical Equations
Get yourself an
unbalanced
equation
Balancing Chemical Equations
Draw boxes around all the
chemical formulas. Never, ever,
change anything inside the boxes.
Ever. Really. If you do, you're
guaranteed to get the answer
wrong.
Balancing Chemical Equations
Make an element inventory.
You have to make an
inventory of how many atoms
of each element you have, and
then you have to keep it
current throughout the whole
problem.
Balancing Chemical Equations
Write numbers in front of
each of the boxes until the
inventory for each element is
the same both before and after
the reaction.
Balancing Chemical Equations
Whenever you change a
number, make sure to update
the inventory - otherwise, you
run the risk of balancing it
incorrectly.
Balancing Chemical Equations
When all the numbers in the
inventory balance, then the
equation can balance,
NH4Cl + NaNO2
NaCl + N2 + H2O
Cl + NaOH
NaCl + NaClO + H2O
Cl + NaOH
NaCl + NaClO + H2O
Pb(NO3)2
PbO +
NO2 + O2
Hg2O + O2
HgO
CaO + MgCl2
MgO +
CaCl2
Ca + H2O
Ca(OH)2 + H2
CrCl3 + H2SO4
Cr(SO 4)3 + HCl
Fe(NO3)3 + NH 4OH
Fe(OH)3 + NH4NO3
AlCl3 + K3 PO4
AlPO4 + KCl
Al2O3 + C + Cl2
CO + AlCl3
Cu2O + HCl +
CuCl + H2O
Mg(HCO3)2 + HCl
MgCl2 + H2O + CO2
Fe + O2
Fe2O3
Si + H2O
SiO2 + H2
Writing Word Equations From Chemical
Equations take out your polyatomic ion sheet from
last semester
HC2H3O2(aq) + NaHCO3(s)
NaC2H3O2(aq) + H2O(l) + CO2(g)
Xe (g) + 3F2(g)
XeF6 (s)
2H2O(l) + nrg
2H2(g) + O2(g)
CH4 (g) + 2O2(g)
CO2(g) + 2H2O(g) + NRG
H2CO3(aq)
H2O(l) + CO2(g)
2NaOH (aq) + CO2(g)
Na2CO3 (s) + H2O(l)
C (s) +O2 (g)
CO2(g)
2H2(g) + O2(g)
2H2O(g) + NRG
MgCl2(aq) + 2AgNO3 (aq)
Mg(NO3)2 (aq) +
2AgCl(s)
AgNO3 (aq) + NaBr (aq)
AgBr(s) + NaNO3(aq)
C5H12 (l) +8O2(g)
5CO2(g) + 6H2O(g)
CoCO3 (s) + NRG
CoO(s) + CO2(g)
BaCO3(s) + C(s) + H2O(g)
2CO(g) +
Ba(OH)2(s)
Word Equations Notes
EVERY EQUATION FOLLOWS
THIS PATTERN
REACTANTS
PRODUCTS
Word Equations Notes
A+ SIGN ON THE REACTANT
SIDE MEANS “REACTS
WITH”
A + SIGN ON THE PRODUCT
SIDE MEANS “AND”
Word Equations Notes
H2O (l) = WATER
H2O(g) = WATER VAPOR
H20(s) = ICE
DIATOMIC ELEMENTS…
ARE ELEMENTS THAT EXIST
IS NATURE AS A MOLECULE
OF TWO ATOMS OF
THEMSELVES BONDED
TOGETHER
DIATOMIC ELEMENTS
MEMORIZE THESE:
H2(g)= HYDROGEN GAS
N2(g)= NITROGEN GAS
O2 (g)= OXYGEN GAS
F2(g)= FLUORINE GAS
Cl2(g)= CHLORINE GAS
Br2(g)= BROMINE GAS
I2 (g)= IODINE GAS
Writing Word Equations From
Chemical Equations take out your
polyatomic ion sheet from last
semester
HC2H3O2(aq) + NaHCO3(s)
NaC2H3O2(aq) + H2O(l)
+ CO2(g)
Xe (g) + 3F2(g)
XeF6 (s)
2H2O(l) + nrg
+ O2(g)
2H2(g)
CH4 (g) + 2O2(g)
2H2O(g) + NRG
CO2(g) +
H2CO3(aq)
H2O(l) + CO2(g)
2NaOH (aq) + CO2(g)
Na2CO3 (s) + H2O(l)
C (s) +O2 (g)
CO2(g)
2H2(g) + O2(g)
NRG
2H2O(g) +
MgCl2(aq) + 2AgNO3 (aq)
Mg(NO3)2 (aq) +
2AgCl(s)
AgNO3 (aq) + NaBr (aq)
AgBr(s) + NaNO3(aq)
C5H12 (l) +8O2(g)
5CO2(g) + 6H2O(g)
CoCO3 (s) + NRG
+ CO2(g)
CoO(s)
BaCO3(s) + C(s) + H2O(g)
2CO(g) + Ba(OH)2(s)
More Practice Writing Word
Equations: Balance each first
MgBr2 (aq) + Cl2 (g)
MgCl2 (aq) + Br2(g)
Fe(s) + O2(g)
Fe2O3(s)
H2O(l) + N2O3(g)
HNO2(aq)
Na2O(s) + H2O(l)
NaOH(aq)
Fe(s) + H2O(l)
Fe3O4(s) +
H2(g)
Write balanced
chemical
equations from
word equations
1) Aqueous magnesium
bromide reacts with
chlorine gas to produce
aqueous magnesium
chloride and bromine
gas.
2) Chlorine gas reacts
with solid sodium
iodide to produce solid
sodium chloride and
iodine gas.
3) Solid potassium
nitrate produces solid
potassium nitrate and
oxygen gas
4) Solid zinc reacts with
aqueous hydrogen
monochloride to
produce aqueous zinc(I)
chloride and hydrogen
gas
5) Solid calcium oxide
reacts with aqueous
hydrogen monochloride
to produce aqueous
calcium chloride and
water.
6) Solid sodium reacts
with chlorine gas to
produce solid sodium
chloride.
7) Bromine gas reacts
with water and sulfur
dioxide gas to produce
aqueous hydrogen
monobromide and
aqueous hydrogen
sulfate.
8) Solid calcium oxide
reacts with water to
produce aqueous
calcium hydroxide.
9) Solid diphosphorus
pentaoxide reacts with
solid barium oxide to
produce solid barium
phosphate.
10) Solid iron reacts with
liquid sulfur to produce
solid iron(II)sulfide
11) Solid sodium reacts
with water to produce
aqueous sodium
hydroxide and
hydrogen gas.
12) Aqueous
copper(I)chloride
reacts with dihydrogen
sulfide gas to produce
solid copper(I)sulfide
and aqueous hydrogen
monochloride.
13) Solid aluminum
reacts with aqueous
lead(II)nitrate to
produce aqueous
aluminum nitrate and
solid lead.
14) Solid magnesium
reacts with oxygen gas
to produce solid
magnesiumoxide.
15) Aqueous hydrogen
carbonate produces
carbon dioxide gas and
water.
Types of Reactions:
--Distinguish between the 5 major
type of chemical reactions
--Classify a reaction as belonging
to one of the 5 major types
What is a reactant?
Any substance that
undergoes a reaction
5 MAJOR CLASSES OF RXNS
SYNTHESIS
DECOMPOSITION
SINGLE DISPLACEMENT
DOUBLE DISPLACEMENT
COMBUSTION
SYNTHESIS
2 OR MORE SUBSTANCES
COMBINE TO FORM ONE
PRODUCT. (2 or more reactant
yields 1 product)
EX:
3Fe(s) + O2(g)
Fe3O2(s)
+
Decomposition
1 reactant is broken down into 2
or more products.
EX: 2H2O(l)
2H2(g) + O2(g)
EX: 2H2O(l)
2H2(g) + O2(g)
+
Single displacement a.k.a. single
replacement
2 reacts, 1 is an element and the
other is a compound, 2 products,
one is an element the other a
compound. The metal element
takes the place of the metal
element in the compound OR
nonmetal replaces nonmetal
Single displacement
EX: Fe(s) + CuSO4(aq)
FeSO4(aq)
+
Cu(s) +
+
DOUBLE DISPLACEMENT
a.k.a. DOUBLE REPLACMENT
THE POSITIVE IONS OF TWO
IONIC COMPOUNDS ARE
INTERCHANGED. AT LEAST
ONE PRODUCT MUST BE
WATER OR A PRECIPITATE
Double displacement
EX: PbCl2(s) + Li2SO4(aq)
PbSO4(s) + 2LiCl(aq)
+
+
Combustion
Means burning in oxygen;
products will be carbon dioxide
CO2 and water H2O
Identify each reaction type below
1.
2.
3.
4.
5.
6.
7.
8.
A+B
AB
A + BC
B + AC
X + YZ
Z + YX
MN + OP
MP + ON
CH + O2
CO2 + H2O
XY
X+Y
S+T
ST
G + HI
H + GI
1. Synthesis
2. Single replacement
3. Single replacement
4. Decomposition
5. Decomposition
6. Decomposition
7. Double replacement
8. Synthesis
9. Double replacement
10. Double replacement
11. Single replacement
12.
13.
14.
15.
single replacement
single replacement
double replacement
single replacement
BALANCE EACH
EQUATION AND
IDENTIFY THE TYPE
ANSWER
KEY