Bonding Lab
Wrapping things up
Checking results: station 5
check below- your solutions may have been
contaminated!
Compound
Bond Type
Conductivity
C6H8O6 (ascorbic acid)
Covalent
8
Glycerin
Covalent
1-2
C12H22O11 (sucrose)
Covalent
0-1
H2O (water)
Covalent
0
C3H7OH (rubbing alcohol)
Covalent
0-1
NaCl (salt)
Ionic
9
Cu(NO3)2 (copper nitrate)
Ionic
10
K2C2O4 (potassium oxalate) Ionic
8
Mg(NO3)2 (magnesium
nitrate)
9
Ionic
Station 7 Conclusion:
Compounds w/ionic bonding contain
metals & non-metals (ex: NaCl,
Na=M, Cl=NM). Compounds
w/metallic bonding contain only
metals (ex: Zn=M). Compounds
w/covalent or network covalent
bonding are made of NMs (ex:
Sugar=C6H12O6, C&H&O=NMs).
2.1.1 Bond Types
Bonds
• Bonds = the attraction that holds atoms together
• Two or more atoms may form bonds in order to
make a compound
– Example: the elements hydrogen (H) and
oxygen (O) can form a bond to make the
compound water (H2O)
What am I
doing here?
4 different types of bonds
ionic
Network
covalent
metallic
Covalent
(molecular)
Ionic
“ion” = a charged particle
How these bonds form:
• Metal atoms give up their valence electrons to
the non-metals
• Metals form positive ions (lose e-)
• Non-metals form negative ions (gain e-)
• Attraction due to opposite charges holds the
atoms together
Properties of Ionic Compounds
•
•
•
•
•
Made of metal & non-metal atoms
Dissolve in water
Conduct electricity when dissolved
Do not conduct when solid
Brittle
Covalent (molecular)
How these bonds form:
• Valence electrons are shared between groups of
atoms
• These groups of atoms are called “molecules”
Properties of Molecular Covalent Compounds
•
•
•
•
Made of nonmetals
Some dissolve in water, some don’t
Do not conduct electricity
Are liquids or gases or soft solids
Network covalent
How these bonds form:
• Valence electrons connect atoms together in all
directions- a giant network of connected atoms
Properties of Covalent Network Compounds
•
•
•
•
Made of nonmetal atoms
Do not dissolve in water
Do not conduct electricity
Very hard solids
Metallic
How these bonds form:
• Electrons move freely, not associated with any
particular atom
• “Sea of electrons”
Properties of Metallic Compounds
•
•
•
•
Made of metal atoms
Do not dissolve in water
Conduct electricity
Are bendable solids
Ionic Bonds
•
•
•
•
Hold two ions together
Anion = negative ion
Cation = positive ion
Opposite charges attract
Na +
cation
Cl anion
Why do ionic solutions conduct?
• Crystal lattice dissolves in water to form
individual ions
• Movement of ions allows current to flow
Why does tap water conduct electricity
and not pure, de-ionized water?
• Your tap water may have…
– Chlorine
– Dissolved minerals such as calcium and magnesium
– Sodium
– Fluoride
H2O
Na+
H2O
Cl -
Pure Water
FMg2+
Tap Water
Bonding Animations
http://www.mhhe.com/physsci/chemistry/anim
ations/chang_7e_esp/bom1s2_11.swf
http://ithacasciencezone.com/chemzone/lesson
s/03bonding/mleebonding/default.htm
Check your work! (2.1.1)
“step two”
Ionic
NaCl
CuCl2
NaOH
MgSO4
Covalent
network
C
Si
SiO2
Metallic
Na
Cu
Hg
Pt
Molecular
covalent
H2O
CH4
CH3CH2OH
1. Which model would you predict for the
following substances? Explain your reasoning.
C6H12O6 (sugar)
Molecular Covalent, it is made
of non-metals & dissolves in
water.
KI (potassium iodide)
Ionic, it is made of a metal & a
non-metal.
MgO (magnesium oxide)
Ionic, it is made of a metal & a
non-metal.
Au (gold)
Metallic, it is made of only
metal atoms.
CO2 (carbon dioxide gas)
Molecular Covalent, it is made
of non-metals & is a gas.
2. In the ionic solid, Model 1, the non-metal
atoms have a negative charge & the metal
atoms have a positive charge. What do you
think causes these charges?
Gaining & losing electrons!
Gaining electrons = negative charge
Losing electrons = positive charge
3. In the metallic solid, Model 3, the “sea” of
electrons has a negative charge. What charge
would the spherical atoms have? Explain.
Positive charge because they
are attracting the “sea” of
electrons.
4. In covalent substances electrons are shared
between atoms. What differences do you see
in Models 2 & 4?
In Model 2, electrons are being
shared between 4 atoms.
In Model 4, electrons are only
being shared between 2 atoms.
5. Use the models to explain the following
evidence:
a) Molecular covalent substances are often
gases
The atoms are not as connected so they can “fly away”
as a gas.
b) Ionic substances are brittle
Because they don’t share electrons, they are not as
connected & can break easily.
1. Compare & contrast each of the following
pairs of bonding types with respect to i) the
role of electrons in bonding and ii) physical
properties of the bonded materials such as
hardness:
a) Ionic bonding & covalent bonding
In ionic bonding, electrons are transferred from a
metal to a non-metal. In covalent bonding, electrons
are shared between 2 non-metals.
Substances with ionic bonding are solids and
substances with covalent bonding are liquids or
gases.
1. Compare & contrast each of the following pairs of
bonding types with respect to i) the role of
electrons in bonding and ii) physical properties of
the bonded materials such as hardness:
a) Network covalent bonding & metallic bonding
In network covalent bonding, electrons are shared
between non-metals all around. In metallic bonding,
atoms are surrounded by a sea of electrons.
Substances with both of these types of bonding are
hard solids. Only metals conduct electricity though.
2. You observed NO2(g) when you dissolved Cu(s) in
nitric acid in the copper cycle lab. How would you
classify the bonding in NO2 (g)? Explain.
Molecular covalent because both N & O are nonmetals & it’s a gas.
3. Think about the physical properties of the
following substances, and decide which type of
bonding you would probably find in each
substance. Explain your reasoning.
a) hair gel
Covalent—it’s a liquid.
b) silver bracelet
Metallic—it’s made of only metals.
c) motor oil
Covalent—it’s a liquid.
d) sodium bicarbonate
Ionic—it’s a solid (& has metals & nonmetals).
4. Look at the chemical makeup of the following
substances & decide which type of bonding you
would probably find in each substance.
a) Zn (s) zinc
Metallic
b) C3H8 (l) propane
Covalent
c) CaCO3 (s) calcium carbonate
Ionic