Download Chapter 2 power point File

Matter and Atoms
Chapter 2
(Page 36)
Essential Question

How does kinetic energy determine the
phases and physical properties of matter?
Vocabulary: section 1










Substance
Mixture
Physical property
Physical change
Chemical property
Chemical change
Chemical reaction
Scale
Microscopic
macroscopic








Element
Periodic table
Element symbol
Atomic number
Period
Group
Atomic mass unit
Avogadro's number
What are things made of?
The “stuff” that we are made of is called matter.
Chemistry tells us how one kind of matter can be changed
into a completely different kind of matter.
What is an Atom?
Everything in the world is made up of
small particles called atoms
 Atoms are the smallest form of matter
 The atoms that are in your body are the
same as the atoms that are in rocks,
water, plastic and metals
 Your body, plastic and wood all have high
amounts of carbon
 Chemistry is the study of matter, how it is
formed, and how one type of matter can
become another type of matter

What is a substance?
There are over 1 million different types of
matter around the classroom
 Scientists use different techniques to find
out if things (substances) are pure or
mixtures
 A substance is matter that cannot be
separated into different kinds of matter by
physical means such as sorting, filtering,
drying, dissolving, heating or cooling
 Corn oil is a pure substance and salad
dressing is not

What are things made of?
How many different kinds of substances can you identify?
Is “pure orange juice”
a pure substance?
“Pure orange juice”
•
•
•
•
•
•
Water
Flavoring chemicals
Citric acid
Sugars
Fruit pulp
…
What is a mixture?
Orange juice may say pure on the
container, but it is actually made up of
many different things (so it is a mixture)
 Orange juice can be separated into water,
different flavoring chemicals, citric acid,
sugars and fruit pulp
 A mixture is anything that contains more
than one substance
 Wood is also a mixture because it is made
up of water, tannic acid, lignin and other
chemicals

What is the difference between a substance and a
mixture?
Oil and vinegar
dressing is
a mixture of
substances
Corn oil is a pure
substance
mixture: matter that contains more than one substance.
substance: a kind of matter that can’t be separated into
other substances by physical means such as heating,
cooling, filtering, drying, sorting, or dissolving.
What are physical properties?
Physical properties are properties that can
be measured using the 5 senses
 Color, density, malleability (able to be
beaten into sheets), brittle, solid, liquid, or
gas, hard, soft, wet, dry are all physical
properties
 Physical changes are changes in state:
from solid to liquid to gas

Look at your desk – What is it made of?
wood, metal…
Can you think of a few physical properties?
is it heavy?
is it bendable?
does it feel cold?
can you scratch it?
…
What are physical changes?
Physical changes include changes
in shape, phase or temperature.
What are Chemical Properties?
What are Chemical Changes?





Chemical properties – can only be observed when one
substance changes into a different one ( such as
rusting)
Chemical change – any change that transforms one
substance into a different one (and are hard to reverse)
Chemical changes are created by chemical reactions
Chemical reaction – any process that changes a
substance into a different one
Examples of chemical reactions include turning cloudy,
temperature change, bubbling, and color change
Chemical properties
are observed when
a substance changes into
a different substance.
Chemical change
Iron
Rust
How can you determine if there is a
chemical change?
Signs
that a
chemical change
has occurred
What are scales?
What scales are used in science?




Scales are used by scientists to measure
samples and to find out specific information
A meter scale measures things that are large
(length of a car), a centimeter measures things
that are small (the length of a book), and a
millimeter measures things that are microscopic
or really small (like the thickness of a fingernail,
or a penny)
Macroscopic scales measures things as small as
tiny bacteria to things as large as planets
Microscopic scales measures things that are
really small 10-9 or smaller
What are atoms and where do you
find them?
All matter in the world is made up of atoms
 Atoms make up everything that you can
taste, smell, see and touch
 A single grain of sand contains over 200
million million atoms
 A single grain of sand is 10-10 meters in
diameter so it would take 10, 000, 000, 000
atoms side by side to measure one meter in
length

What are elements?
What is the difference between and
atom and an element?





Sand has a mineral called feldspar in it that is a
substance
Feldspar contains the elements oxygen, silicon
and potassium
Elements are the smallest forms of matter that
have similar characteristics
Elements can also be called specialized atoms,
or atoms with unique characteristics
Oxygen atoms look, act and react differently to
silicon atoms
How do scientist organize all
the elements?
How is the Periodic Table organized?




The periodic table is a special table designed to
show all 118 atoms, where they are located and
what other atoms they are similar to
The periodic table arranges elements according
to how they combine with other elements
(chemical properties)
Most of the periodic table is made up of metals
(on the left and in the middle)
The nonmetals are found on the right
What are the properties of
Metal?
Metals are shiny solids at room
temperature (except mercury)
 Conduct heat and electricity
 Malleable (beaten into sheets)
 Ductile (can be made into wires)

What are the properties of NonMetals?
Poor conductors of heat and electricity
 They are brittle (break easily)
 Only one nonmetal bromine is a liquid at
room temperature

The periodic table
Increasing atomic number
Increasing atomic number
Increasing atomic number
Increasing atomic number
Hydrogen
Lightest element
Atomic number: 1
Uranium
Heaviest naturally occurring element
Atomic number: 92
What does the atomic number
represent?





Each element on the periodic table has an atomic
number that identifies it and makes it different from
all other elements
The atomic number is the number of protons an
element has (positive in charge)
The number of protons also is the same as the
number of electrons an element has (negative in
charge)
Atoms of each element are neutral in charge since
the positives and negatives cancel out
Elements in the periodic table are arranged from
the lightest to the heaviest (in progressive order)
How is the Periodic table
organized?




The periodic table of elements was put
together by early scientist who saw
similarities between certain elements
For example, lithium, sodium, and potassium
reacted with oxygen in ratios of two metals for
each oxygen
The rows (from left to right) shows elements
as they increase in the number of protons
(atomic number)
The columns shows all the elements with the
most similar characteristics such as reactivity
The periodic table organizes elements according to how they combine with
other elements (based on their chemical properties).





Each element in the periodic table has its
own box that identifies it with special features
Each box has an upper case letter then one
or two lower case letter which identifies it
(called the symbol)
Each box also has a small number called the
atomic number (the number of protons the
element has)
Each box also has a larger number called the
atomic mass (equal to the number of protons
and neutrons combined)
Neutrons are sub atomic particles like protons
and electrons that are found in the nucleus
Elements that belong to the same group (column) have
similar chemical properties.
Reminder
1 atomic mass unit (amu) = 1.66 x 10-24 g
Period 1 has only 2 elements
 Period 2 has 8 elements
 Period 3 has 8 elements
 Period 4 has 18 elements
 Period 5 has 18 elements
 Period 6 has 32 elements
 Period 7 has 32 elements







An element is so small that you need a small unit
just to measure them
Atomic mass unit (amu) is 1.66 x 10-24 g
The atom carbon has a weight of 12 amu
Hydrogen has a weight of 1 amu
The large number in each square of the periodic
table is an element’s average weight in amu
The atomic mass has two important
interpretations: 1. the mass of a single atom in
amu, 2. the mass of one mole of atoms in grams
We cannot measure amu easily so we use
larger units called grams. So, when you
see the atomic mass of carbon (12 amu)
we use 12 grams to represent one mole of
carbon, 1 amu of hydrogen is 1 gram and
16 amu of oxygen represents 16 grams
which all equal one mole of carbon,
hydrogen and oxygen respectively
 In one mole of every substance is a very
large number 6.022 x 1023 which is called
Avogadro’s number

Scientist know that amu are too small to
work with daily so they work with moles of
atoms
 A mole of atoms is the same as the atom,
or elements atomic weight (in grams)
 There are two types of problems used to
calculate answers:

Moles to mass of substance
 Mass in grams to number of moles of sample

Avogadro’s number
One mole contains
6.02 x 1023 atoms
How many moles are in 100 g of sulfur (S)?
Asked:
Given:
Relationships:
The number of moles
The element is sulfur and there are 100 g
One mole of sulfur has a mass of 32.065 g
How many grams of calcium (Ca) do you need
to have 2.50 moles of calcium?
Asked:
Given:
Relationships:
The number of grams
The element is calcium and there are 2.50 moles
One mole of calcium has a mass of 40.078 g
Class Assignment
Write a one three dollar summary of what you
learned in this section (be very specific and be
very thorough).
 Turn to page 66 and answer questions 1 – 11
then turn in the assignment.


Honors Chemistry Homework:
page 67 # 30 - 40
Vocabulary: section 2









Molecule
Compound
Chemical formula
Ball and stick model
Structural diagram
Space filling model
Molecular surface
Ionic compound
ion

Formula mass
If you cut a piece of
wax, is it still wax?
If you cut that smaller
piece again, is it still
wax?
When does it stop
being wax?





A bowl of wax can be broken down over and
over until it cannot be broken down anymore
without loosing its properties and you would
have a molecule of wax
A single molecule is the smallest particle a
substance can be
A molecule is two or more atoms bonded
together
Wax is a compound made up of carbon and
hydrogen
Pure elements are hard to find in nature
One O2 molecule
One H2 molecule
One H2O molecule
molecule: a group of atoms chemically bonded together.
compound: a substance containing more than one
element in which atoms of different elements are
chemically bonded together.





Most elements are so reactive that they are
hardly found pure in nature
Gold is an element that can be found pure in
nature
Hydrogen and oxygen easily form water instead
of being in their pure form
Salt is also a compound of sodium and chlorine
Pure sugar is also a compound made up of
carbon hydrogen and oxygen





Compounds and mixtures are different
Mixtures are not combined chemically
When compounds are made the elements that
make them up give up their individual properties
and the compound has new properties
A compound is a molecule with two or more
different atoms combined chemically
Soda is a mixture of sugar, water and carbon
dioxide (not chemically bonded)
There are only 26 letters of the alphabet
and yet there are tens of thousands of
words in a dictionary
 There are 92 naturally occurring elements
and so there are trillions of compounds
possible
 Paraffin is made up of 21 carbon and 44
hydrogen atoms in a long chain
 Aspirin is made up of 9 carbon, 4 oxygen
and 8 hydrogen

What do all these have in common?
They are made up of only 3 types of atoms:
carbon, oxygen and hydrogen.
The properties of a compound depend more on
the exact structure of the molecule
than on the individual elements from which it is made.
Assignment

On the same sheet of paper, (in the third
section), please write six more things that
you learned from your notes so far that
could appear on your test.
Many things that we use daily are made of
plastics (man made polymers)
 Polymers are repeating chains of
molecules
 Polyethylene is a polymer used to make
bags, bottles, toys and other daily items
 Rayon was the first artificial silk produced
and was made of cellulose polymers





Chemical formulas are the way that scientist use
to identify compounds
Chemical formulas tell the compounds needed
and how many of each are required to make the
compound correctly
H2O tells you that to make water you need two
hydrogen and one oxygen (the 2 is called a
subscript)
Compounds contain different ratios of elements



The properties of compounds depends on the
structure of its molecules more than the
individual elements that make them
For example, aspirin fights swelling and pain,
but if any of the carbons or hydrogen are
removed, the structure changes and the
properties are no longer there
The same 21 atoms in aspirin can be rearranged
to make other compounds that are not useful to
us in daily life (acetyl benzoyl peroxide,



To completely describe a real molecule you
must know its composition as well as its
structure
Knowing the composition is not enough since
there are a number of ways that the molecules
can be arranged
There are 5 ways that a compound can be
represented: chemical formula, structural
diagrams, ball and stick model, space filling
model, and molecular surface
Assignment

On the same sheet of paper, (on the back
side of the paper), please write six more
things that you learned from your notes so
far that could appear on your test.




Structural diagram shows bonds, connections
between atoms in the molecule
Ball and stick model gives you the three
dimensional with angels
Space-filling model shows how close the atoms
really are and how they overlap in each other’s
space
Molecular surface model combines the ball and
stick model to give transparent view of the
molecule
Chemical Bonds and Electrons
A chemical bond
forms when atoms
transfer or share
electrons.
 A covalent bond is
formed when atoms
share electrons.

Types of Bonds




Ionic bond- a chemical bond resulting from
electrostatic attraction between positive and
negative ions (between a metal and non metal)
pure ionic bond - electrons are transferred.
Ionic compounds cannot form molecules
because each atom has a chemical bond with
the atom next to it as well as an associated
bond with the elements around it
An ion is a charged atom with a positive
(metal) or negative (nonmetal) charge
Types of Bonds
 Covalent
bond- a chemical bond
resulting from the sharing of
electrons between two atoms
(between two nonmetals)
Formula mass

The sum of the atomic mass values of the
atoms in a chemical formula is called the
formula mass.
Assignment

On a blank sheet of paper, (in the second
section of the back side), please write six
things that you learned from your notes so
far that could appear on your test.
Moles and Avogadro’s Number





A mole is equal to an elements atoms mass (the
big number in the square of the elements
periodic box)
A mole is also equal to the sum of all the
elements in a molecule or a compound
Avogadro’s number is 6.022 X 1023 atoms
This number represents the number of atoms
that can be counted in one mole of a substance
Even though the masses will change from atom
to atom, the amount of atoms will always be the
same in one mole 6.022 X 1023
Sample Questions

What is the mass of 1 mole of methane
with the chemical formula CH4?

How many moles are in 100 grams of
water?

How many moles are in 25 g of copper
oxide (CuO)?
Questions Cont.

How many grams are in 2.3 moles of
butane (C4H10)?

How many moles are in 30g of baking
soda (NaHCO3)?
Assignment

Write a three dollar summary of what you
learned in this section (be very specific and be
very thorough.

Turn to page 66 and answer questions 12 – 18
then turn in the assignment.

Honors Chemistry Homework:
page 67 # 42 - 46
Vocabulary: section 3








Homogeneous
mixture
Heterogeneous
mixture
Solution
Solvent
Solute
Dissolved
Concentration
dilute






Concentrated
Solubility
Insoluble
Molarity
Molar volume
Dalton’s law of partial
pressures
A recipe calls for you to “mix until homogeneous.”
What does that mean?
A mixture that is uniform throughout.
Different samples may have
different compositions.



Most matter is made up of many different
compounds
A homogeneous mixture is where all parts of the
mixture are uniformly mixed (a sample taken
from the top is the same as a sample taken from
the bottom)
Brass is made up of 70 % copper and 30 % zinc
(if you take a sample of brass from different
locations they would be the same percentage
throughout)


A heterogeneous solution is one where samples
taken would have different concentrations of
what makes them (example Italian dressing or
concrete)
Now you have four types of matter




Homogeneous mixture – more than one type of
matter mixed together uniformly
Heterogeneous mixture – more than one type of
matter mixed differently throughout
Element – a substance containing only one type of
atom
Compound – a substance containing more than one
type of atom chemically bonded together
A solution – a mixture that is
homogeneous
 A solvent – a substance that makes up the
biggest percentage of the mixture (usually
a liquid)
 Solutes – any substance in a solution
other than the solvent
 Dissolved – when molecules of a solute
are completely separated from each other
and dispersed into a solution

What happens when sugar
is added to water?
A solution is obtained.



Concentration of a solution describes how much
of each solute there is compared to the total
solution
A solution is said to be dilute when there is very
little solute compared to the total solution
Mixing one gram of sugar in 99 mL of water
makes 100 grams of dilute sugar solution (a 10
gram sample of this solution only contains 0.1 g
of sugar compared to 9.9 g of water)
These four solutions contain the same solvent and solute.
Which one is the most concentrated solution?
Which one is the most dilute solution?
A solution is concentrated when there is a
lot of dissolved solute compared to solvent
( 5 grams of sugar dissolved in 5 grams of
water)
 Solubility – the amount of solute that is
capable of being dissolved in a solvent
 Solubility is often listed as grams dissolved
per 100 ml of solvent
 Solubility is often given with a temperature
because it changes with temperature
 Things are called insoluble when they do
not dissolve in a given solvent

concentration: the amount of each solute compared to
the total solution.
Solubility of common substances in water at 25oC
solubility: the amount of a solute that will dissolve in
a particular solvent at a particular temperature and
pressure.
Assignment

On the same sheet of paper, (on the third
side of the back side), please write six
things that you learned from your notes so
far that could appear on your test.
Calculating solution volume from solute and concentration
mass of solute

Concentration g/L =
liters of solution
mass of solute

liters of solution =
concentration
Example

If the concentration of a sugar solution is
75 g/L, how much solution do you need if
you want 10 g of sugar?
Asked – volume of solution
Given – 10 grams of solute and
concentration of 75 g/L
Solve 10 g / 75 g/L = 0.133 liters = 133 ml
If the concentration of a sugar solution is 75 g/L, how much solution
do you need if you want 10 g of sugar?
Asked:
Volume of solution
Given:
10 g of solute and concentration of 75 g/L
Relationships:
Liters of solution 
Solve:
10 g
 0.133 L or 133 mL
75 g L
mass of solute
concentration in g L
Try

If the concentration of a sugar solution is 90
g/L, how much solution do you need if you
want 15 g of sugar?
Asked – volume of solution
Given – 15 grams of solute and concentration
of 90 g/L
Solve:
g / g/L =
liters =
ml
Calculating solute mass from solution and % concentration
mass of solute
Concentration % =
X 100
Mass of solution
concentration
mass of solute = mass of solution X
100
Example

How much menthol do you need to make 10
kg of mouthwash if the concentration of
menthol is 0.05 %?
Asked – mass of solute
Given – 10 kilograms of solution, and
concentration of 0.05%
Solve 10 kg X (0.05 / 100) = 0.005 kg = 5 g
How much menthol do you need to make 10 kg of mouthwash if
the concentration of menthol must be 0.05%?
Asked:
Mass of solute
Given:
10 kg of solution, solute concentration of 0.05%
Relationships:
Solve:
 concentration in % 
mass of solute  mass of solution  

100


 0.05% 
10 kg  
  0.005 kg or 5 g
10
0


Try

How much menthol do you need to make 17
kg of mouthwash if the concentration of
menthol is 0.15 %?
Asked – mass of solute
Given – 17 kilograms of solution, and
concentration of 0.15%
Solve kg X ( / 100) =
kg =
g
Molarity is the number of moles of solute
per liter of solution
 Molarity helps scientist control the ratios of
different molecules in reactions
 When chemist know the molarity, they can
figure out how many moles are needed,
and how many milliliters of solution are
needed


To find the molarity you must know how
many moles of solute are dissolved in the
solution

Steps to finding molarity
Calculate the formula mass
 Use the formula mass to figure out how many
moles there are
 Calculate molarity by dividing the number of
moles by the volume of solution

Example
10 g of citric acid C6H8O7 is added to 500 mL of
water. What is the molarity of the resulting solution?
Asked – find the molarity of the solution
Given – amount of solute, citric acid and volume
of solution
Molarity = moles of solute / volume of solution
Solve: formula mass (6 x12 + 8 x 1 + 7 x 16)
# moles = 10 g / 192 g/mol = 0.052 moles
Molarity = 0.052 / 0.5 L = 0.104 M

Try
25 g of citric acid C6H8O7 is added to 600 mL
of water. What is the molarity of the resulting
solution?
Asked – find the molarity of the solution
Given – amount of solute, citric acid and
volume of solution
Molarity = moles of solute / volume of solution

Ascorbic acid = Vitamin C
Ascorbic acid
C6H8O6
Vitamin C acts as a food
preservative by reacting
with oxygen (O2)
How much (volume) of a 1 M ascorbic acid solution will completely
react with 0.02 moles of oxygen (O2)?
Asked:
Volume of solution
Given:
Concentration (1M) and balanced reaction
Relationships:
molarity 
moles solute
volume of solution  L 
According to the balanced reaction we need 2 moles of ascorbic
acid for every mole of O2.
How much (volume) of a 1 M ascorbic acid solution will completely
react with 0.02 moles of oxygen (O2)?
Asked:
Volume of solution
Given:
Concentration (1M) and balanced reaction
Relationships:
molarity 
moles solute
volume of solution  L 
According to the balanced reaction we need 2 moles of ascorbic
acid for every mole of O2.
Solve:
That means we need 0.04 moles of ascorbic acid:
moles solute 0.04 moles
volume  L  

 0.04 L or 40 mL
molarity
1M
Answer:
40 mL of the solution contains 0.04 moles of ascorbic acid,
which is enough to react with 0.02 moles of oxygen (O2).
Class Assignment
Write a three dollar summary of what you
learned in this section (be very specific and be
very thorough).
 Turn to page 66 and answer questions 19 – 29
then turn in the assignment.


Honors Chemistry Homework
page 69 # 47 - 52
Air takes up less space under high pressure.
molar volume: the amount
of space occupied by a mole
of gas at STP.
It is equal to 22.4 L.
Standard
Temperature and
Pressure
0oC
1 atm




Many mixtures are gases, like air
Gases can contract and expand to fill the
container they are in
Concentration in a mixture is usually given as a
percent by volume (because gases at the same
temperature, same pressure have the same
volume per mole)
The volume is 22.4 L, the temperature is
O oC and the pressure is 1 atmosphere also
know as STP
The air you breathe is a mixture!





Air is made up of a mixture of gases
Dry air contains about 78% nitrogen, 21% oxygen
and 1% other gases
The air we breath has about 1% moisture in it and
at sea level it has a pressure of 101,325 pascals or
101.325 Kpa (1 atm)
This 101.325 is the total pressure from all the
gasses in air
Dalton (a chemist) came up with a law known as
the law of partial pressures
Partial pressures
The total pressure in
a mixture of gases is the
sum of the partial
pressures
of each individual gas
in the mixture.
Partial pressures
Gas A
+
Gas B
Gas A
Gas B
Gas C
Total pressure
=
Partial pressure
of A
+
Partial pressure
of B
Gas C
Partial pressure
of C
Test: - Next week Tuesday or Thursday
depending on your class.

Homework requirement: Learn all terms and
concepts covered on this topic.

Make sure you have all assignments
between page 36 and 69 completed and
turned in by your test date.