Bellwork: Wednesday 4/11/2012
Write formulas for how the following elements
would form Ionic compounds
Calcium
+ Silicon Ca+2 + Si-4  Ca Si
2
Sodium
+ Bromine +1
Na + Br-1  NaBr
Boron
+ Fluorine
B+3 + F-1  BF3
+1 + S-2  K S
K
2
Potassium + Sulfur
Example #1-Names to Formulas
1. Write symbols of elements
Aluminum chloride
2. Determine number of ions
(Al +3)x(Cl-1)y
This formula says that
the +3 charge of one Al
atom will cancel the-3
charge from 3 Cl atoms
x(+3) + y(-1) = 0
1(+3) + 3(-1) = 0
Al1 Cl3
If thereFinal
is only Formula
one atom the “1” is
not shown
Example #2-Names to Formulas
1. Write symbols of elements
2. Determine number of ions
Choose the lowest
set of integers that
satisfies the
equation
X= 1
Y 2
2X = 1y
X(+2) + y(-1) = 0
(Co+2)x(BrO3-1)y= 0
Cobalt (II) bromate
Co1(BrO3 )2
If there
is onlyFormula
one atom the “1” is
Final
not shown
Example #3-Names to Formulas
1. Write symbols of elements
2. Determine number of ions
X= 1
Y 3
3X = 1y
X(+3) + y(-1) = 0
(Ni+3)x(C2H3O2-1)y= 0
Nickel (III) acetate
Choose the lowest
set of integers that
satisfies the
equation
Ni1 (C2H3O2)3
Final
Formula
If there
is only
one atom the “1” is
not shown
Example #4-Names to Formulas
1. Write symbols of elements
2. Determine number of ions
X =3
Y 1
1X = 3y
X(+1) + y(-3) = 0
(Li+1 )x(PO4-3)y= 0
Lithium phosphate
Li3(PO4 )1
Final
If there
is onlyFormula
one atom the “1” is
not shown
Names to Formulas: Criss-Cross Method
Barium nitrate
1. Write the formulas for the cation and
anion, including CHARGES!
2. Check to see if charges are balanced.
2+
Ba
3. Balance charges, if necessary, using
subscripts. Use parentheses if you need
more than one of a polyatomic ion. Use
the criss-cross method to balance the
subscripts.
( NO3-) 2
Now balanced.
Not balanced!
= Ba(NO3)2
Names to Formulas: Criss-Cross Method
Iron (III) chloride
1. Write the formulas for the cation and
anion, including CHARGES!
2. Check to see if charges are balanced.
3. Balance charges, if necessary, using
subscripts. Use parentheses if you need
more than one of a polyatomic ion. Use
the criss-cross method to balance the
subscripts.
Fe3+ Cl-
3
Now balanced.
Not balanced!
= FeCl3
Names to Formulas: Criss-Cross Method
Ammonium sulfate
1. Write the formulas for the cation and
anion, including CHARGES!
(NH4
2. Check to see if charges are balanced.
3. Balance charges, if necessary, using
subscripts. Use parentheses if you need
more than one of a polyatomic ion. Use
the criss-cross method to balance the
subscripts.
+)
2
SO42-
Now balanced.
Not balanced!
= (NH4)2SO4
Names to Formulas: Criss-Cross Method
Aluminum sulfide
1. Write the formulas for the cation and
anion, including CHARGES!
2. Check to see if charges are balanced.
3. Balance charges, if necessary, using
subscripts. Use parentheses if you need
more than one of a polyatomic ion. Use
the criss-cross method to balance the
subscripts.
3+
Al
2
2S
3
Now balanced.
Not balanced!
= Al2S3
DNA- The Master Molecule of
Life- page 12
 Deoxyribonucleic Acid
(DNA): A
long, large molecule shaped like a
twisted ladder (double helix). The
plans for who you are and what you
look like are chemically stored in the
DNA (like a blueprint).
 In 1953, Francis Crick and James Watson
discovered that DNA is shaped like a
ladder coiled into a 'double helix' shape.
 Macromolecule:
A very large
molecule made from thousands of
atoms (ex. DNA)
VIDEO- DNA: Master Molecule of Life
As you watch the following videos, fill out
the video guide provided- page 12
 Video- Importance  Video- DNA Subunits
of DNA 1.34
3.45
1.
2.
3.
4.
5.
Molecule
Cells
Molecules/DNA
Genetic code
True
Macromolecule
7. 2
8. False
9. 4
10. Backbone
11. A and T, G and C
6.
Components of DNA
Nucleotide Subunit: what DNA is made up of; each
 ‘Rungs’ of the ladder- 2
nucleotide has:
nitrogenous (nitrogen
‘Sides’ of the ladder(linked chains of alternating
sugar and phosphate
molecules)
 phosphate
 sugar
containing) bases attached
to the sugar molecules (4
different types of bases)
 Adenine (A)
 Thymine (T)
 Cytosine (C)
 Guanine (G)
○ They link together in
pairs (A with T, C with
G) to form a rung
○ The order of the bases
and rungs creates a
kind of code for the
DNA information.
Sides of the ladder: “Sugar-Phosphate Backbone”

Sugar
(deoxyribose)
 5 carbon ring
 Each corner of the
pentagon
represents a
Carbon—they just
don’t write it!

Phosphate PO43−
 Polyatomic Ion!
 Octet Rule- atoms tend to gain,
lose, or share electrons until they
have eight electrons in their
valence shell.
 Given what you know about the
chemical formula for the
phosphate functional group, you
can say that the rule is
disobeyed in this case.
Page 13- What five elements make up the
DNA macromolecule?
1.
2.
3.
4.
5.
Phosphorus
Carbon
Hydrogen
Oxygen
Nitrogen

The DNA
double helix is
stabilized by
hydrogen
bonds between
the bases
attached to the
two strands.
AT base pair
With two hydrogen bonds
 Hydrogen bonds are shown as dashed lines

GC base pair

With three hydrogen bonds
DNA Sequencing- page 13

PRACTICE: What would be the pair for:
ACC
TGG

GAC
CTG
TAC
ATG
Finish the DNA sequencing individually, then check
answers together as a class
ATC GCT TGA GAG CAT TAG GCA TGT
TAG CGA ACT CTC GTA ATC CGT ACA
Increasing knowledge about DNA
creates more complicated possibilities
for the future…
 Cloning-
the
process of making
a genetically
identical organism
through nonsexual
means
 Natural
cloning is
identical twins
 genetically
different from
parents
 What
do you think
about the possibilities
for human cloning?
 If you could make a
clone of yourself,
would you do it?
 Why or why not?
 Record your
answers in the
space provided
Cloning- KWL— Fill -in the “Know”
and “Wonder” column NOW
Know
1.
2.
things you
already know
about cloning
Wonder
1.
2.
things you
wonder about
cloning
Learned
1.
2.
3.
4.
things you
learned about
cloning during
that will follow
Video: The Clone Age
As you watch the video…
…write
four new things you learned
on your KWL chart- page 13
…pay attention to the scientific
process involved in creating a clone
…note where hereditary information
is stored in a cell and how this
information may be altered
1st Cloned
Mammal
1997- Scotland
 Sheep named Dolly
 276 attempts before
success

Dolly
 What do you think happened
to the unsuccessful attempts??
Dolly’s
clone—
NOT her
baby!
Respond to the following questions in 3-4
complete sentences on page 13 for
homework.
1.
Discuss the ethics of cloning only the best
and brightest of the human race.
2. If you were in charge of undertaking a
cloning project, which qualities would
you look for when selecting your
cloning subjects? Explain why.
Remaining Time: Discuss questions as a class.
EXTRA TIME? Practice Ionic Naming
Formulas to Names & Names to Formulas
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Na2SO4
Fe(NO3)2
PbI4
(NH4)3PO4
Na2CO3
Be(OH)2
Magnesium
Hydroxide
Magnesium nitride
Silver Acetate
Aluminum Chloride
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Sodium Sulfate
Iron (II) Nitrate
Lead (IV) iodide
Ammonium
Phosphate
Sodium carbonate
Beryllium Hydroxide
Mg(OH)2
Mg3N2
AgC2H3O2
AlCl3
EXTRA TIME? Practice Ionic Naming
Names to Formulas
Calcium Carbonate
2. Potassium Chloride
3. Iron (II) Sulfate
4. Lithium bromide
5. Magnesium chloride
6. Iron (III) chloride
7. Zinc Phosphate
8. Ammonium Nitrate
9. Aluminum hydroxide
10. Copper (I) Acetate
11. Lead (II) Sulfite
12. Sodium Chlorate
13. Calcium Oxalate
1.
Iron (III) Oxide
15. Ammonium Phosphate
16. Sodium hydrogen sulfate
17. Mercury (I) chloride
18. Magnesium nitrate
19. Copper (II) sulfate
20. Sodium hydrogen carbonate
21. Nickel (III) bromide
22. Beryllium nitrate
23. Zinc sulfate
24. Gold (III) chloride
25. Potassium permanganate
14.