Download Chapter 3: AtomicMass.ppt

Catalyst
1. Pick up white board and marker from front!
2. Take out your catalyst sheet and answer the
questions below by naming the following
compounds:
1. NF3
2. Li2S
3. NH4OH
4. Pb(MnO4)2
TRADE AND GRADE
Catalyst
Take out your catalyst sheet and answer the
questions below by naming the following
compounds:
1. NF3 – Nitrogen Trifluoride
2. Li2S – Lithium Sulfide
3. NH4OH – Ammonium Hydroxide
4. Pb(MnO4)2 – Lead (II)
Permanganate
BIG GOAL
Explosion!
(3 MINUTES)
Explosion
Questions
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
What is the scientific method? 17.
What is a Law?
18.
What is a theory?
19.
What is the formula for
density?
What is a chemical property? 20.
What is a physical property? 21.
What is the law of
22.
conservation of mass?
What is a Law?
23.
What is a theory?
What is precision?
24.
What is accuracy?
Where can I find a fire
25.
extinguisher?
Who discovered the electron?
What are the three types of
radiation?
Who is Ernest Rutherford?
Is the atomic mass or atomic
number always bigger?
How do you find the number
of neutrons?
What is an isotope?
What is the formula for
Nitrate?
What is the formula for
Chlorate?
What is the formula for
Sulfate?
What is a covalent
compound?
What is an ionic compound?
Atomic Mass
Why is it that we never see Carbon-12
on the periodic table? We always see
12.0111…
Atomic Mass given on the periodic table is
calculated based on the relative abundance
(how common) an isotope is!
Eqn:
% abundance (Atomic Mass of isotope 1) +
% abundance (Atomic Mass of isotope 2) + etc…
=
Average Atomic Mass
Atomic mass is measured in amu which
stands for “atomic mass unit”
It was determined using Carbon-12!
Carbon -12 is exactly 12 amu, and all other values
can be found accordingly…
Mass C
=1.083
12
Mass C
13
So Mass Carbon – 13 = 1.083 x 12amu
So Mass Carbon – 13 = 13.0034 amu
Let’s look at example about Natural Carbon: Carbon12 is 98.89% abundant, Carbon-13 is 1.11%
abundant, and Carbon-14 is negligibly small (we
don’t count it because it’s too close to 0). What is
the average atomic mass for natural carbon?
Now it is your turn to try, do Supp problems!
The Mole
1 mole = the number of Carbon atoms in
exactly 12 grams of pure Carbon-12
Avogadro’s number: 6.022*1023
1 mole = 6.022*1023 units of that
substance (just like a dozen!)
Let’s put it in prospective…
1 mole of seconds is a span of time 4 million
times as long as the earth has already existed
Let’s put it in prospective…
1 mole of marbles would cover the
Earth to a depth of 50 miles!
Since atoms are soooo tiny, a mole is
manageable for us to measure and
calculate!
Let’s try a mole calculation!
Compute the mass in grams of 6 atoms
of Americium
What units are Caution!Where units are
We can’t
jump from
atoms
you starting
Must
gojust
through
moles!
to mass!you ending with?
with?
atoms
mass
moles
Let’s try a mole calculation!
Compute the number of atoms of
100.0 grams of Calcium
What units are
Where units are
you starting
Must go through moles!
you ending with?
with?
mass
atoms
moles
Molar Mass
Used to Calculate the mass per mole of a
compound!
Molar mass: the mass in grams of 1 mole
of that substance
Formula:
#atoms(atomic mass) +
#atoms(atomic mass) +
Etc… = total Molar Mass
Let’s try calculating the Molar Mass for
Mg(OH)2
How many Mg atoms do I have in this
compound?
1
What is the Atomic Mass of Mg? 24.3 g/mol
= 24.3 g/mol
Let’s try calculating the Molar Mass for
Mg(OH)2
= 24.3 g/mol
How many Oxygen atoms do I have in this
compound?
2
What is the Atomic Mass of Mg? 16.0 g/mol
= 32.0 g/mol
Let’s try calculating the Molar Mass for
Mg(OH)2
= 24.3 g/mol
= 32.0 g/mol
How many Hydrogen atoms do I have in this
compound?
2
What is the Atomic Mass of Mg?
1.0 g/mol
= 2.0 g/mol
Let’s try calculating the Molar Mass for
Mg(OH)2
= 24.3 g/mol
= 32.0 g/mol
= 2.0 g/mol
Total Molar Mass for Mg(OH)2 =
58.3 g/mol
Now you try!
Calculate the Molar Mass of KMnO4
Calculate
Let’s put
the everything
number of we
molecules
learnedin 54
grams
together!
of CO2.
Must go through moles!
What units are
you starting
with?
Where units are
you ending with?
mass
molecules
moles
Calculate the number of molecules in 54
grams of CO2.
Molar Mass!
mass
Avogadro’s #
moles
molecules
Step 1: Calculate the Molar Mass of CO2
Step 2: Set up conversion
(just like dimensional analysis!)
Step 3: Apply units only…and make sure they cancel
out!
Step 4: Fill in numbers and calculate
Calculate the mass of in 1.7*1024
molecules of NH3.
What units are
you starting
with?
molecules
Where units are
you ending with?
moles
mass
USE THE SAME STEPS AS BEFORE!