Jeremy decides to make some Macaroni and Cheese from a
box. He notices the directions ask him to add salt to water
before bringing it to a boil. The next day, Jeremy asks his
science teacher “How does adding salt to water affect the
way it boils?” They plan an experiment to find out the
answer. The following graph summarizes Jeremy’s findings.
List all of the materials and equipment that Jeremy
would have to use in his experiment.
Using Jeremy’s experiment, identify:
1. the independent variable.
2. the dependent variable.
3. the experimental control group.
4. Jeremy’s probable conclusion.
Which formula represents a
molecular compound?
(1) HI
(3) KCl
(2) KI
(4) LiCl
Which type of matter is
composed of two or more
elements that are chemically
combined in a fixed proportion?
(1) solution
(2) compound
(3) homogeneous mixture
(4) heterogeneous mixture
EX 1: Convert 1006051 to
scientific notation.
1006051
The natural
decimal point
is here
Decimal will
move here
1.006051 x
6
10
6 because the decimal moved 6 times
65
30
2+
Determine the number of
protons, neutrons, electrons,
and the mass number
30 protons, 35
neutrons, 28
electrons, mass
number = 65
EX 2: Convert 0.0052300 to
scientific notation.
0 0052300
The natural
decimal point
is here
Decimal will
move here
5.2300 x
-3
10
Negative because the original number is less than
1 and 3 because the decimal moved 3 times
EX: Determine the number of significant figures in
a) 4
1
2
b) 4.0
1
c) 40
d) 0.0400 3
e) 4004
4
f) 0.0004 1
Practice
EX 1: Determine the number of significant
figures in:
a)
b)
c)
d)
e)
f)
2
5.0
10
0.0400
8005
3.00 x 103
1
2
1
3
4
3
EX 2: Convert each of the values into
scientific notation while retaining the
same number of sig figs
a)
b)
c)
d)
60000
20
4004
0.0900
6 x 104
2 x 101
4.004 x 103
9.00 x 10-2
Lets practice together…
Round the following numbers to 3 sig figs
a) 51.234
51.2
Or 5.12 x 101
1
Or
5.14
x
10
b) 51.38
51.4
51.4
Or 5.14 x 101
c) 51.3587
51,400
Or 5.14 x 104
d) 51,358
-2
0.0506
Or
5.06
x
10
e) 0.050554
YOUR Practice
•
EX: Round the following numbers
to 3 sig figs
a) 51.234
51.2
b) 51.38
51.4
c) 51.3587
51.4
d) 51,358
51,400
e) 0.050554
0.0506
f) 5,135,593
5,140,000
Example:
2.8
1
2
3
4
5
6
7
8
9
It is expected that you will always
report all sig figs on any laboratory
reading!
10
Example:
2.71
1
2
3
4
5
6
7
8
9
It is expected that you will always
report all sig figs on any laboratory
reading!
10
Which Lewis electron-dot
diagram represents
calcium oxide?
Explain which of the following
represent pure substances
and which represent
mixtures.
Practice
1) 22.101 mL – 0.9307 mL
= 21.170 mL
2) 2.5 g / 3.42 g = 0.73 g
3) 2.33 cm x 6.085 cm x 2.1 cm
= 30. cm3
4) 23.1 in + 4.77 in + 125.39 in +
3.581 in = 156.8 in
• EX: 37.24 mL + 10.3 mL =
• 27.87 g – 2.2342 g =
47.5 mL
25.64 g
Rules for Math Operations with
Significant Figures
Addition and Subtraction
Ex. 37.24mL
+ 10.3 mL
47.54mL
Reported as 47.5mL
Rules for Math Operations with
Significant Figures
Addition and Subtraction
Ex. 27.87 g
- 21.2342 g
6.6358 g
Reported as 6.64g
2. Multiplication and Division
• The measurement with the fewest sig figs
determines the number of sig figs in the
answer
• EX: 12.34 cm X 0.23 cm =
2.8 cm2
Practice
•
2. Determine the number of g in 0.03455 kg
Relationship
1000g = 1kg
want
Start with what’s given
0.03455 kg
1
1000 g = 34.6 g
1 kg
given
• Ex. 2 Convert 323 mL to cups
Relationships
given
want
1000 mL = 1L
1L = 1.06 quarts
1 quart = 4 cups
Start with what’s given
323 mL
1
1L
1000 mL
1.06 qt.
1L
4 cups
1 qt.
= 1.37 cups
• Practice 1: Convert 7.005 ft to mm
Relationships
1 foot = 12 inches
given
want
2.54cm = 1 in
100 cm = 1 m
1 m = 1000 mm
Start with what’s given
7.005 ft 12 in
1
1 ft
2.54 cm 1 m 1000 mm
1 in
100 cm 1 m
= 2135 mm
• EX 1: Convert 0.083 km/h to m/s
Relationships
1km = 1000m
given
want
1h = 60 min
1 min = 60 s
Start with what’s given
0.083km
1hr
1000m 1 hr
1 min
1 km 60 min 60 s
= 2.31 X 10-2 m/s
•
1. Convert 3.56 cm/s to ft/h
Relationships
2.54 cm = 1 in
given
want
12 in = 1 ft
60 s = 1 min
1 hr = 60 min
Start with what’s given
1 ft
60 s 60 min
3.56 cm 1 in
1s
2.54 cm 12 in 1 min 1 hr
= 420 ft/hr
•
2. Convert $25.00/feet to cents/cm
Relationships
$1 = 100 cents
given
want
2.54 cm = 1 in
12 in = 1 ft
Start with what’s given
$ 25.00 100 cents
1 ft
$1
1 ft
12 in
1 in
2.54 cm
= 82.0 cents/cm
Determine the number of
centimeters in 1.76 kilometers
(Show all dimensional analysis.)
Determine the number of inches in
697 mm.
Note: 2.54 cm = 1 inch
(Show all dimensional analysis.)
Determine the number of atoms
in 5.20 moles of C6H12 .
(Show all dimensional analysis.)
How many significant figures do the
following numbers contain?
A) 4,250.00
B) 4040
C) 0.009
D) 325.08
E) 6.02 x 1023
Find the answer to the following
using the correct number of
significant figures.
A) 4,250.38 + 25.1
B) 4040 x 32
Read the following to the correct
number of significant figures.
Which statement describes a chemical
property of bromine?
(1) Bromine is soluble in water.
(2) Bromine has a reddish-brown color.
(3) Bromine combines with aluminum to
produce AlBr3.
(4) Bromine changes from a liquid to a
gas at 332 K and 1 atm.
An atom of aluminum in the
ground state and an atom of
gallium in the ground state have
the same (1) mass
(2) electronegativity
(3) total number of protons
(4) total number of valence
electrons
In an atom of argon-40, the number
of protons –
(1) equals the number of electrons
(2) equals the number of neutrons
(3) is less than the number of
electrons
(4) is greater than the number of
electrons
Which type of substance can
conduct electricity in the liquid
phase but not in the solid phase?
(1) ionic compound
(2) molecular compound
(3) metallic element
(4) nonmetallic element
Why is a molecule of CO2 nonpolar even
though the bonds between the carbon atom
and the oxygen atoms are polar?
(1) The shape of the CO2 molecule is
symmetrical.
(2) The shape of the CO2 molecule is
asymmetrical.
(3) The CO2 molecule has a deficiency of
electrons.
(4) The CO2 molecule has an excess of
electrons.
The relatively high boiling
point of water is due to water
having(1) hydrogen bonding
(2) metallic bonding
(3) nonpolar covalent bonding
(4) strong ionic bonding
Matter is classified as a (1) substance, only
(2) substance or as a mixture of
substances
(3) homogenous mixture, only
(4) homogenous mixture or as a
heterogeneous mixture
Which substance can not be
decomposed by a chemical
change?
(1) ammonia (3) propanol
(2) copper (4) water
A beaker contains both alcohol
and water. These liquids can be
separated by distillation
because the liquids have different
(1) boiling points (3) particle sizes
(2) densities (4) solubilities
A sample of an element is
malleable and can conduct
electricity. This element could
be (1) H
(3) S
(2) He
(4) Sn
Identify the element in Period 3 of
the Periodic Table that reacts with
oxygen to form
an ionic compound represented by
the formula X2O.
Based on data collected during a laboratory
investigation, a student determined an
experimental value of 322 joules per gram for
the heat of fusion of H2O. Calculate the
student’s percent error. Your response must
include a correct numerical setup and the
calculated result.
Calculate the density of a 129.5gram sample of bronze that has a
volume of 14.8 cubic
centimeters. Your response must
include a correct numerical setup
and the calculated
result.
8.75 g/cm3
Atomic Structure
Questions
Answers
Determine the number of protons,
neutrons, and electrons in an ion
of magnesium with a 2+ charge
and a mass number of 25.
+
p
= 12
0
n = 13
e = 10
True or False?
Elements cannot
be created, divided,
or destroyed
False
Elements can be
divided
(particle accelerators/
atom smashers)
Determine the
element’s identity:
Relative Abundance
Element – 28 92.23%
Element – 29 4.67%
Element – 30 3.10%
Silicon
The Gold Foil
experiment resulted
in the discovery of
the ______
Nucleus!
Europium has two naturallyoccurring isotopes: europium151 with an abundance of
47.82% and europium-153 with
an abundance of 52.18%.
Determine the average atomic
mass for europium.
152.0436 amu
Who developed the
plum pudding
model?
JJ Thompson
How can you
determine the mass
number?
Protons + neutrons
What is fluorine’s
most abundant
isotope?
Fluorine - 19
All atoms of an
element are
________ from
another element
All atoms of an
element are
different from
another element
Who discovered
the electron?
JJ Thompson
3
1
Determine the number of
protons, neutrons, and the
mass number
1 proton, 2
neutrons, mass
number = 3
If 3 protons could be removed from
the nucleus of an Nitrogen atom,
what nucleus remains?
Beryllium
7p – 3p = 4p
Determine which element has a
mass number of 45 and has 14
neutrons.
Gallium
Determine the number
of protons, neutrons,
and electrons in an
atom of silicon-29.
protons = 14
neutrons = 15
electrons = 14
Write the isotope for the element
given that it has 12 protons and
14 neutrons. Show the isotope
in both ways.
Magnesium – 26
26
12
Mg
What part of the
atom takes up the
most amount of
space?
electrons
What element is
used as the
standard for atomic
mass units?
carbon
The end of an electron
4
configuration says 4d .
What element is
represented?
What does n represent?
Why can’t we have two up
spins next to each other?
What is the roman
numeral of the group
3
found at np ?
How many orbitals have
electrons in the configuration:
2
2
6
1
1s 2s 2p 3s
***hint***you
probably want to write out the
orbital notation.