Transcript What do you remember about ionic bonding and ionic compounds?

Reminder
• When the timer reaches 0:
• You must have your notebook out and
open,
• Have a pen or pencil ready
• And, if there was homework, have it out
on your desk.
• Then, copy the objective and ANSWER the Do
Now questions.
• 4 January 2010
• Objective: SWBAT differentiate between
ionic and covalent bonding.
• Do Now:
a) Write the name for Pb(NO3)2
b) Is Pb(NO3)2 ionic or covalent?
c) Name one PROPERTY of ionic compounds.
Announcements
• Four days this week – Covalent
compounds – properties, names, drawing
diagrams.
• Two days next week – shapes of covalent
molecules.
• Then, midterm review (4 days)!!
• Midterms are the (short) week of January
18.
Announcements
• I will post missing assignments for
quarter 2 tomorrow in room 104.
• If you haven’t taken the Ions and Ionic
Compounds test, you must do so by
Friday!!!
• Seating survey tomorrow; new seats later
this week.
What do you remember about ionic
bonding and ionic compounds?
• Which elements? Electronegativity?
• How does it work?
• Properties of ionic compounds?
Ionic or Covalent?
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NaCl
NO2
N2Br
NaI
CaS
Ionic or Covalent?
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KNO3
Fe(CrO4)2
Cu(OH)2
BaI
F2
Ionic or Covalent?
• O2
• AgCl
• AgNO3
Covalent Bonding
Covalent Bonding
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two or more non-metals
all with high electronegativity
ions are NOT formed!!
atoms share some valence electrons
(not transfer) to make a full octet of 8
• usually each atom donates (shares) one
of each pair of electrons
F
F
Electron Pair
Shared by both atoms
One e- shared by each atom
• number of bonds formed depends on the
number of e- required to fill the valence
shell
– noble gases = full valence, rarely form
compounds
• octet rule: usually, atoms want 8 valence
e- (H, He need 2)
• Ex: C has 4 valence e– needs 4 more to form a full octet
– C forms 4 bonds
• Ex: F has 7 valence e– needs 1 more to form a full octet
– F makes one bond
• Nitrogen? Oxygen?
• Demonstration!
• (the return of the little white balls)
Properties of Covalent Compounds
• covalent bonds = strong
• forces between molecules = weaker
– covalent molecules are easily separated
from one another
– soft solids (l or g at room temp)
– do not conduct electricity
– not very soluble in water
– low melting/boiling points (liquid or gas
at room temperature)
Examples of Covalent Compounds
Videos!
• http://www.youtube.com/watch?v=Qqjc
CvzWwww
• http://www.youtube.com/watch?v=yjge1
WdCFPs&feature=PlayList&p=8D43FC9FA
07913EF&playnext=1&playnext_from=PL
&index=23
• http://www.youtube.com/watch?v=F54r
qDh2mWA
• 6 January 2010
• Objective: SWBAT name and write formulae
for covalent compounds.
• Do Now:
What is the difference between ionic and
covalent compounds? (Write at least two
complete sentences.)
Agenda
I. Seating/success survey
II. Naming covalent compounds
III. Writing formulae for covalent
compounds
Announcements
• Missing work is on bulletin board in 104.
• Did you take the Ions and Ionic
Compounds test?
• Last day to hand in missing work:
– Tues. Jan. 12
• Midterm: Wed. Jan. 20
– 10:20 am-12:10 pm
How did we name ionic compounds?
Naming Covalent Compounds
• P2O5
• What do the little numbers (subscripts)
mean?!
– Subscripts = The number of atoms of
each element!!
• Use prefixes to communicate how many
atoms of each element.
Prefix System
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1 – mono*
2 – di
3 – tri
4 – tetra
5 – penta
*never use mono if the FIRST element
listed in a compound has one atom.
• The SECOND element gets an “-ide”
ending
Write names or formulae
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6.
7.
NO2
CO2
PCl5
P2S4
Nitrogen trioxide
Carbon monoxide
Dinitrogen tetrahydride
Name these covalent compounds
1.
2.
3.
4.
5.
6.
7.
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NH3
CH4
CF4
H2O
P3O5
SBr2
P2O3
What is the ratio of nitrogen atoms to
hydrogen atoms in NH3?
Write formulae
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2.
3.
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6.
7.
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Dinitrogen monoxide
Carbon tetrachloride
Oxygen difluoride
Sulfur trioxide
Dichlorine octoxide
Sulfur dibromide
Dioxide difluoride
Xenon tetrafluoride
Homework
• Week 18 Homework #6-7
• 7 January 2010
• Objective: SWBAT draw Lewis dot
structures for covalent compounds.
• Do Now:
P2O5
a) Ionic or covalent? Name it.
b) What is the ratio of phosphorus to
oxygen?
c) Name one property you would expect
this compound to have.
Agenda
I. Go over homework (correct it!)
II. How to draw Lewis dot structures
III. Lots of practice on whiteboards!
Homework: Finish Week 18 Homework –
due tomorrow
Announcements
• Missing work is on bulletin board in 104.
• Did you take the Ions and Ionic
Compounds test?
• Last day to hand in missing work:
– Tues. Jan. 12
• Midterm: Wed. Jan. 20
– 10:20 am-12:10 pm
• 7 January 2010
• Objective: SWBAT name, write formulae for,
and diagram ionic and covalent
compounds.
• Do Now:
Draw the Lewis Dot Structure for HCN.
Agenda
I.
II.
Homework answers, collect HW
Review stations
I.
II.
Naming ionic and covalent compounds
Formulae of ionic and covalent
compounds
III. Properties
IV. Lewis dot structures
Bonding between C and F
F
F
F C F F C F
F
F
structural
formula
hybrid
diagram
=e- pair
=covalent bond
F
F C F
F
Lewis dot
structure
F e - C e-
Double Bond
• sharing two pairs of electrons
• bonds more strongly than a single bond
O C O O C O O C O
• structural
hybrid
Lewis
Triple Bond
• Strongest
N N
N N
N N
Drawing molecule diagrams
1. Decide how many bonds each atom
makes.
2. The central atom is the one that makes
the most bonds.
3. Draw with single bonds
4. Calculate remaining electrons
5. Use remaining electrons
• HCN (hydrogen cyanide)
– C=4, N=3, H=1
• HCO2- (methanoate ion)
– H=1, C=4, O=2
Draw structural, hybrid and Lewis
structures
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HF
NH3
CH4
CF4
NO2-
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CHCl3
NH4+
H2CO
SeF2
Names and Formulae
All Mixed Up!
These are ionic OR covalent!
If given the name, write the formula
If given the formula, write the name
Length and Strength of Bonds
single
longest
lowest energy
double
triple
shortest
highest energy
– sometimes, a solid lattice is held together
with covalent bonds
• covalent network (giant covalent
structures): very hard, very high
melting/boiling points
– Examples: diamonds and graphite (both
C), SiO2