Welcome to Chem 1A
Significant Figures
Any non zero number is significant
54, _______ significant figures
Zeros between other significant numbers are significant
504, _______ significant figures
Zeros left of non zero digit aren’t significant
0.00504, _______ significant figures
0000454, _______ significant figures
For numbers greater than 1 all zeros right of decimal point are
significant.
2.000, _____ significant figures
Trailing zeros are not significant unless decimal point/sci notation is
used.
4200, _______ significant figures
4200., _______significant figures
4.20x103 _____ significant figures.
Significant Figures cont…
Addition and Subtraction: use lowest number of
“places”, decimal points, tens, hundreds ect….
0.24 + 0.345 = _______
3233 + 1300 = _______
Multiplication and Division: use lowest number of
significant figures.
23*436 = ________
453 / 3.2 = _______
Dimensional Analysis: Conversion
Factors
The average speed of helium at 25°C is 1255 m/s.
Convert this to miles per hour
How many minutes does it take light from the sun to
reach earth given that the distance from the sun is 93
million miles and the speed of light is 3.00x108m/s
Structure of an atom
Bohr Model
Isotopes, Natural Abundance, and molecular masses
What is an isotope?
________________________________
Why are molecular masses on the periodic
table decimal points?
51.839% 107Ag and the rest is 109Ag. Find
the weighted average molecular mass.
Periodic Table
Empirical vs. Chemical
Formulas
Hydrazine
Ethane
1,2-Ethanediol
Molecular
Formula
N2H4
C2H6
C2H6O2
Empirical
Formula
NH2
CH3
CH3O
Naming
Ionic
Lots of memorization: It is a pain. I know. Its also worth
it so please, just do it.
Molecular
Acids
Organic
Don’t worry about it too much. I’ll refer to it from time
to time, you have homework on it, but I won’t test you
on it.
Bonding: Finding that special
element(s) that completes you
Share or take electrons to be isoelectronic with
noble gas. aka have a full octet.
I have 6 valence
electrons.
Me too!
How about me and you go back
to my place and form a covalent
bond or two?
Types of Bonds
Ionic:
•“__________” electrons
•___________________
Covalent: •“________” electrons
•________________
Metallic: •delocalized electrons
NaCl
CO
Ag
•metals
•electrically conductive
•collective description of many bonds
Ionic Bonds
K
+
+
K
I
I
- •Elements want a
___________________
• Electrons are __________
• Elements develop a _______
F
+ Mg +
F
-
2+ -
F Mg F
Lewis Dot
Structure
Making Ionic Compounds
3+
Al
2O
Making Ionic Compounds
2+
Mg
2O
Charges of Atoms
You need to
know:
Ions shown here
Including ions
with multiple
charges
Polyatomic ions
Inert Pair Effect
Tendency of heavier atoms
to form ions with a
difference in charge of two.
Eventually we’ll use
electron configurations to
figure out the reasons for
this.
For now, why do you think
it is?
Section 1.19
Naming: Ionic Compounds:
Extra notes for you:
You need to know:
Ions on last slide, use group of periodic table to help
with memorizing.
Polyatomic ions- see following slides
Ions with multiple charges- see following slides
Naming Ionic Compounds:
Memorization Help
-ate, -ite, ide
per-, hypo-
-ous
-ic
Memorize all –ate OR –ite in a
group, then know that –ate,
have one more oxygen atom
than -ite
-ic has one more charge than ous
use the periodic table to help
with charges
Chapter 2
Naming
Ionic
Compounds
Acids
-ous
-ic
-ic has one more charge than –ous
-ate ions turn into –ic acids,
-ite ions turn into –ous acids
Chapter 2
Ionic Naming Practice
Write the formula of the
following:
Write the name of the
following:
Aluminum Oxide
FeCl2 and FeCl3
Silver Sulfate
Rb(SCN)2
Magnesium cyanide
SnF2
Zinc Oxide
Na3PO4
Covalent bonding: Molecular Compounds
In a covalent bond electrons are shared
Cl
+ Cl
Covalent bonding: Molecular Compounds
In a covalent bond electrons are shared
2 O
O O
O O
Chapter 2
Naming: Molecular Compounds
Composed of ________________
Prefix on the first word, ______________
Prefix on second word, ____________
Add ________as suffix to second word
Molecular Compounds: Naming Practice
Write the formula of the
following:
Carbon Monoxide
Nitrogen trihydride
Sulfur dioxide
Sulfur hexafluoride
Write the name of the following:
S2F10
N2H4
PH3
PCl5
Moles, Masses and Chemical Reactions
To convert from
one chemical
species to
another use
____________
from balanced
______________
Example Problems:
Calculate the number of cations and anions in 8.38 g of Na2O
Platinum forms two different compounds with chlorine. One
contains 26.7% Cl by mass and the other 42.1% Cl by mass. Find
the empirical formula of each.
One of the reactions that occurs in a blast furnace where iron ore is
converted to cast iron, is shown below. Suppose that 1.64x103kg
sample of Fe are obtained from 2.62x103 kg Fe2O3. Assuming that
the reaction goes to completion, what is the percent purity of Fe2O3
in the original sample.
Fe2O3+ CO
Fe+CO2
A compound made up of C, H, and Cl contains 55.0% Cl by mass.
If 9.00g of the compound contain 4.19x1023H atoms. What is the
empirical formula of the compound? If the molecular mass is
193.5g/mol what is the molecular formula?
Energy
Energy= capacity to do work
SI unit is J
kg*m2/s2
Kinetic energy
½ mv2
Many types of energy
gravitational potential energy, electromagnetic energy,
thermal energy
Total energy= Potential Energy+Kinetic Energy
Example
Mars orbits the Sun at 25 km/s. A spaceship attempting to land on mars
must match its orbital speed. If the mass of the spaceship is 3.6x105kg,
what is its kinetic energy when its speed has matched that of Mars?
=1.1x1014 kg*m2*s-2=1.1x1014 J