Transcript The Hydrosphere

BRN: What do you see?
Bonding
New section in table of contents
Properties Review
What if we just look at the compounds that conducted
electricity
Compound
Conductivity
Tap water (H2O)
Yes
Sodium Chloride (NaCl)
Yes
Hydrochloric Acid (HCl)
Yes
Lithium Fluoride (LiF)
Yes
What do these compounds have in common?
What is an ionic compound?
How would you define a salt?
A salt is just an ionic compound
So what is an ionic compound?
KC 1: An ionic compound consists of a metal
and a non-metal bound together in a lattice
structure by ionic bonds
Ionic Compounds
 KC2: Ionic Compound = metal + nonmetal
or cation + anion
Ionic Compounds
 KC 3: Cation – positively charged ion
 KC 4: Anion – negatively charged ion
 Polyatomic Ions
 “Poly” = many
 “atomic” = atoms
 Ion = charged
 KC 5: Polyatmoic ion = many atoms bonded
together having an overall charge
 See periodic table
Ionic Bonding
 KC 6: Ionic Bond – bond formed through
electrostatic attraction between 2
oppositely charged ions
 Review: What is an ion?
 Different number of electrons from protons
 Not a neutral atom
 Contains a charge
dissociation animation
8 is the magic number!
• KC 7: All atoms are trying to reach a valence shell
of 8 – like a noble gas
• KC 8: If this cannot be achieved easily, an atom will
lose electrons to have a valence shell of zero
Ionic Bonding
 Each atom forms a charge that is related to its
number of valence electrons
 Example: calcium – 1s22s22p63s23p64s2
 2 valence electrons
 8 is the magic number!
 Is it easier to gain 6 or lose 2?
Ionic Bonding – Ions worksheet
Element Metal/Nonmetal
# Valence
Electrons
# Electrons
to gain
# Electrons
to lose
Ion
Formed/name
Li
Metal
1
None
1
Li1+ / cation
N
Nonmetal
5
3
None
N3- / anion
Ionic Bonding
Naming Rules – formula to name
 There are 3 different “types” of naming rules for
ionic compounds based on what metals and
nonmetals are involved
 Type A: metal + nonmetal
 NaCl
 Type B: metal + anion (polyatomic ions)
 CaCO3
 Type C: transition metal + nonmetal
 CuCl
KC 9: Type A
 Metal + Nonmetal
1. Name the metal
2. Name the nonmetal
3. Change the ending of the nonmetal to “ide”
Example: NaCl – sodium chloride
KC 10: Type B
 Metal + Anion
1. Name the metal
2. Name the anion, but if it is a polyatomic ion,
DO NOT change the ending
Example: CaCO3 – calcium carbonate
EXCEPTION ALERT!!
 There is 1 polyatomic ion that is a cation, which
means it is NOT a metal
 NH4+ - ammonium
 Example: NH4NO3 – ammonium nitrate
KC 11: Type C
 Transition Metal + nonmetal
1. Name the transition metal
2. Figure out the charge of the transition metal
and place in Roman numerals in parenthesis
3. Name the nonmetal:
 If it is a regular nonmetal – change the ending to “ide”
 If it is a polyatomic ion – DO NOT change the ending
Example: CuCl – copper (I) chloride
Creating Ionic Compounds – the
switcheroo!
 KC 12: When bonding a metal and nonmetal in an
ionic compound, the charges have to balance
 To do this, you just switch the charges and cross
them down: the switcheroo
 Can also be done the opposite way to determine
charges
The Switcheroo!
 Example: aluminum chloride
EXCEPTION ALERT!!
 What if you do the switcheroo and the charge for a
nonmetal does not come out correctly?
 Example – CuO
EXCEPTION ALERT!!
 If the charge of the nonmetal comes out wrong, that means
the charges have reduced
 To correct the charge, just multiply both charges by the
necessary number to make it the charge that you know it is
 Example - CuO
Naming Rules - practice
 Practice determining the charges for the
transition metals in the following compounds
 CrO
 CuCl2
 MnO2
KC 13: Name to Formula
1. Write the ion symbol for the cation and anion
with correct charge*
2. Do the switcheroo to balance the charges
For Transition Metals:
*the roman numeral in the name gives you the
charge*
Naming Rules – name to formula
Example: copper (II) chloride
Naming Rules
From your notes, create a tree map of
how to name ionic compounds
There are 3 different types of ionic
compounds
Metal + nonmetal
Transition metal + nonmetal
Metal + polyatomic ion
Naming Ionic Compounds
– formula to name
Type A:
Metal + Nonmetal
Name the metal
Name the
nonmetal
Change the
nonmetal ending
to “ide”
Type B:
Metal +
Polyatomic Ion
Type C: Transition
Metal + Nonmetal
Name the metal
Name the
transition metal
Name the
polyatomic ion
Find the charge of
the metal and
place in roman
numerals
Name the
nonmetal
Covalent Compounds & Bonding
 KC 14: Covalent compounds consist of 2 or
more nonmetals bonded together
 KC 15: A covalent bond is formed from the
sharing of electrons
Ionic Bond
vs.
Covalent Bond
KC 16: Naming Covalent
Compounds
 The rules for molecular compounds are much
easier than ionic (no exceptions…woot!)
1. Write the Greek prefix for the first element
2. Write the name for the first element
3. Write the Greek prefix for the second element
4. Write the name for the second element
Example: N2O5 – dinitrogen pentoxide
Naming Covalent Compounds
 KC 17: Greek Prefixes
1 = mono
2 = di
3 = tri
4 = tetra
5 = penta
6 = hexa
7 = hepta
8 = octa
9 = nano
10 = deca
Naming Covalent Compounds
 Going from name to formula, you just write the
element symbol with the subscript that
matches the prefix from the name
Example: triphosphorus hexafluoride – P3F5
Naming Covalent Compounds
 Create a tree map or flow diagram explaining
how to name covalent compounds
Covalent
Compounds
-formula to name
Write the Greek
prefix for the first
element and name it
Write the prefix for
the second element
and name it
1 = mono
6 = hexa
2 = di
7 = hepta
3 = tri
8 = octa
4 = tetra
9 = nano
5 = penta
10 = deca
Bonding
 KC 18: Some molecules are more stable when they are
found as diatomic – two of the same element
covalently bonded
B I N C H O F
r o i h y x l
BrINClHOF o d t l d y u
m i r o r g o
i n o r o e r
n e g i g n i
e
e n e
n
n e n
e
Bonding
KC 19: Lewis Structure Rules
1.
Draw skeleton of molecule or compound and count total
valence electrons able to use
2.
Give all elements full octet and a single bond between
elements.
3.
Count number of electrons in drawing from step #2 and
compare to number of electrons allowed
4.
If too many, do the “move a pair lose a pair” rule until you
have the correct number of electrons
 Move electrons from outside in to form double or triple bond then
erase a pair of electrons from the outside
EXCEPTION ALERT!!
 How many electrons does hydrogen have?
 Will it be happy with 8?
 NO!
 KC 20: Hydrogen follows the duet rule – only
needs 2 electrons to be happy
Lewis Structure Rules
1. Draw skeleton of molecule or compound and
count total number of valence electrons to use
 Follows logic; place the element that is only contained
once in the middle
Example: CO2
C = 4eO = 6 x 2 = 12e-
Total = 16e-
Lewis Structure Rules
2. Give all elements full octet (8 around each
element) and a single bond between elements.
Example: CO2
16e-
Lewis Structure Rules
3. Count number of electrons in drawing from step
#2 and compare to number of electrons allowed
Example: CO2
Lewis Structure Rules
4. If too many, do the move a pair lose a pair rule until
you have the correct number of electrons
 Move electrons from outside in to form double or triple
bond then erase a pair of electrons from the outside
Example: CO2
**Cannot break octet rule!!**
Lewis Structure Rules
Most Lewis structures for compounds follow
the common bonding patterns:
4 bonds
3 bonds
2 bonds
1 bond
0 L.P.
1 L.P.
2 L.P.
3L.P.
Bonds:
Lone Pairs:
Lewis Structure Practice
On your white boards, draw the Lewis
structure for the following molecules:
CO2
H2O
CH4
CF2Cl2
Shapes of Molecules
 The Lewis structure can be transferred into a 3D
model that tells us the exact shape, bond
angles, and polarity of molecules
# of
things
# bonds
# lone
pairs
Molecular
geometry
Bond
angle
Example
2
0
linear
180
CO2
3
3
0
Trigonal
planar
120
BF3
3
2
1
Bent
<120
SO2
4
4
0
tetrahedral
<109.5
CH4
4
3
1
Trigonal
pyramidal
<109.5
NH3
4
2
2
Bent
<109.5
H2O
2
Polarity
 KC 21: The shape of the molecule and the
electronegativity of the elements determines
the molecule’s polarity
 We use vectors to represent polarity
 Demonstration:
H2O
Your turn!
 You are going to be given a molecule to build
and show to the class
 You must include:
 Name
 Formula
 Lewis structure
 Molecular geometry
 polarity