a. Distinguish between atoms and molecules.
Atoms—smallest unit of any element
Protons• Positively charged
• Found in the nucleus
• Determines the type of element
Neutrons• No electrical charge (neutral)
• Found in the nucleus
Electrons• Negatively charged particles
• Found outside the nucleus in electron clouds
Molecule—two or more atoms joined in a
definite ratio (ex. H2O, C6H12O6, O3)
Mini Review
Which of the following pictures represents
atoms rather than molecules?
Which element has 3 protons?
a. Hydrogen (H) b. Oxygen (O)
c. Lithium (Li)
d. Nitrogen (N)
If the dartboard above is used to model an
atom, which dart indicates where the
protons and neutrons are located?
A Dart W
B Dart X
C Dart Y
D Dart Z
In the equation below, how many molecules
of water are present?
a. 1
b. 2
c. 3
d. 4
How many molecules of methane?
a. 1
b. 2
c. 3
d. 4
What do water, aluminum, redwood trees, and
valley quail all have in common?
A They are all pure elements.
B They are all made of cells.
C They are all living creatures.
D They are all made of atoms
Which of the following represents a molecule?
a. H
b. He
c. O2
d. Cl
The positive subatomic particle that
identifies which element it is called a
a. Proton
b. Neutron
c. Electron
d. Nucleus
The negatively charged subatomic particle
that is involved in bonding with other atoms
to make molecules is called a________.
a. Proton
b. Neutron
c. Electron
d. Nucleus
1.Which statement best describes how atoms
are different from molecules?
a. atoms are the smallest unit of an element
b. molecules are the smallest unit of an
element
c. atoms can be divided, molecules can’t
2.Which of the following materials is
composed of only one kind of atom?
A. Helium
B. A compound
C. An electron
D. A molecule
The picture above shows two hydrogen
atoms chemically bonded to one oxygen
atom. The following picture is an example of
A. an atom
B. an element
C. a molecule
D. a subatomic particle
According to the model which is the chemical
formula for formaldehyde?
A. H2C2O
B. CH2O
C. HCO
D. C2HO
Which of the following pictures represents
only one kind of atom?
A
C
B
D
Which of the following molecules could
represent benzene (CH)?
A
B
C
Which of the following materials is made of
only one kind of atom?
a.He
c. C6H12O6
b.H2O
d. NaCl
Two or more atoms joined in a definite ratio
make a
a. molecule
b. electron
c. atom
d. proton
b. Describe the difference between pure
substances (elements and compounds) and
mixtures.
Matter
Pure
Substances
Elements
Compounds
Mixtures
Pure Substance—substance in which there is
only one type of particle
• Ex. Elements and Compounds
Element—pure substance that cannot be
separated into simpler substances by physical
or chemical means
Compound—a pure substance composed of
two or more different elements that are
chemically combined
Mixture—a combination of two or more
substances that are not chemically combined
ex. air, salt water, salad, brass, milk
Each substance in a mixture has the same
chemical makeup it had before the mixture
formed
Mini Review
Which of the following can be separated into
several elements?
a. nitrogen
b. zinc
c. air
d. aluminum
Which of the following is an example of the
formation of a mixture?
a. Tarnish forming on silver
b. Kool-aid dissolving in water
c. Alka seltzer reacting with water
d. Hydrogen & oxygen reacting to produce water
Salt is composed of sodium and chlorine
chemically combined. Salt is an example of
which of the following?
a. an atom
b. a compound
c. an electron
d. a mixture
Which of these substances is an element?
a. steel
b. chlorine
c. plastic
d. sugar
Which formula represents a compound?
a. SiO2
b. N2
c. Ag
d. Au
What is the main difference between
compounds and mixtures?
a. Mixtures combined chemically while
compounds are combined physically
b. Mixtures are combined physically while
compounds are combined chemically
Which of the following formulas represents a
compound?
A.He
B. N2
C. H2O D. O2
Which of the following is an example of a
container that is filled with a pure substance
rather than with a mixture?
a.A tire filled with air
b.A jar filled with salt water
c.A balloon filled with helium
d.A glass filled with chocolate milk
Which of the following molecules represents
the molecule NH3?
An example of a mixture is
a. Salt (NaCl)
c. Brass
b. Neon (Ne)
d. Water (H2O)
Sterling silver is a combination of silver
and copper. Which of the following is also a
combination of two or more metals?
A aluminum
B lead
C gold
D brass
Which of the following pieces of equipment
should be used to separate this mixture?
A magnet
B balance
C funnel
D hot plate
Which picture below represents a mixture?
A
B
C
D
c. Describe the movement of particles in
solids, liquids, gases, and plasmas states.
Solids
• Have definite shape and volume
• Particles are very close together (strong
attraction)
• Particles vibrate in place
Liquids
• Have definite volume
• Takes the shape of its container
• Particles move more than in a solid but
less than in a gas
Gas
• No definite shape or volume
• Particles move quickly
• Lots of space between particles
Plasma—gas that contains electrically
charged particles
Where can we find plasma?
• Stars
• Nebulas
• Auroras (Northern Lights)
• Certain TVs
• Lightening
Add energy
Add energy
Solid
Solid
Liquid
Take away
energy
Gas
Take away
energy
Liquid
Gas
Mini Review
Bromine can vaporize if heated. This means
that with enough heat, bromine can
a.Be destroyed
b.Change from a liquid to a solid
c.Be changed into a gas
d.Become water vapor
A material has a definite volume but a
changing shape. What is it?
a. A liquid
b. a gas
c. A solid
d. water
Particles would be closest together in which
substance?
A.Kool-Aid
B.A nail
C.Air
D.Water
In which form of water will the particles in a
sample move slowest?
a. Ice
b. liquid water
c. water vapor
d. steam
What happens to the particles of a solid as they
are exposed to warm temperatures?
a.The particles decrease in speed
b.The particles increase in speed
c.The particles become more rigid
d.The motion of the particles is unchanged
Which of the following statements is true of
all different types of matter?
a. The particles move extremely fast and far
apart
b. The particles vibrate in place
c. The particles move at the same speed.
d. The particles are always in motion.
Which substance has a definite shape and
definite volume?
a. a crystal of table salt
b. a solution of saltwater
c. water vapor
d. iced tea
The melting point for water is 0 degrees
Celsius. The boiling point of water is 100
degrees Celsius. At what temperature would
water start to condense?
a. 0
b. 100
What state of matter exists between numbers
3 and 4?
A.
B.
C.
D.
Solid
Liquid
Gas
Plasma
At which point will the particles of water have
the LEAST movement?
A.Point A
C. Point C
B.Point B
D. Point D
A
B
0o
C
D
100o
A scientist uses an instrument to observe the
pattern of molecules in a substance. The picture
below shows what the scientist sees.
What state of matter is the scientist most likely
observing?
A gas
B liquid
C vapor
D solid
Which describes a change from gas to liquid?
a. Boiling
b. condensing
c. Freezing
d. sublimation
What happens to particles when a solid
changes to a liquid?
a.They speed up
b.They slow down
c.Speed doesn’t change
d.They stop moving
When water evaporates it
a. Is a physical change
b. Is a chemical change
c. Is permanently a gas
d. Can not be changed into water again
Which state of matter has the least energy?
A.Solid
B.Liquid
C.Gas
D.Plasma
What happens to particle movement as a gas
becomes a liquid?
a.The particles speed up
b.The particles slow down
c.The particles stop moving
d.The speed of the particles stays the same
d. Distinguish between physical and
chemical properties of matter as physical
(i.e., density, melting point, boiling point) or
chemical (i.e., reactivity, combustibility).
Physical Property—can be observed or
measured without changing the matter’s
identity
Common Physical Properties:
 Magnetism
 Odor
 Conductivity
 Density=m/v
 Strength
 State
 Flexibility
 Ductility
 Volume
 Malleability
 Color
 Solubility
 Boiling Point
 Melting Point
Chemical Property
• Matter’s ability to change into a new
substance that has different properties
and a new chemical composition
• Observed when a chemical change takes
place
Chemical Properties:
Flammability—Flashpoint less than 37.8
degrees Celsius
Combustibility—flashpoint greater than 37.8
degrees Celsius
(the difference between flammability and
combustibility is how easily they ignite—aka
their flashpoints)
Reactivity—the ability of an atom or molecule
to combine with another atom or molecule
Mini Review
Which statement describes a chemical
property of matter?
a.The density of ice is 0.4 g/mL
b.The boiling point of ethanol is 78.4◦C
c.Sodium is a very reactive element
d.Rust is a flaky material with an orange-red
color
A chemical property of aluminum is…
A. Aluminum is silver
B. The density is 10.49 g/cm3
C. The melting point is 962◦C
D. Aluminum does not react with water
Mercury melts at -38.87◦C and boils at
356.58◦C. What is the freezing point of
mercury?
a. -38.87 ◦C
b. 0 ◦C
c. 100 ◦C
d. 356.58 ◦C
What is the volume of a box that is 5cm by
2cm by 3cm?
a. 30cm
b. 30cm3
c. 10cm
d. 10cm3
Which action will result in a product with new
chemical properties?
A shredding newspaper B boiling water
C cutting wood
D burning toast
Which of the following represents a chemical
reaction?
A a sugar cube dissolving in water
B ice cubes forming in a freezer
C ice cream melting in a bowl
D a cake baking in an oven
What is the density of an object that has a
mass of 25grams and a volume of 5cm3?
a. 30g/cm3
b. 125g/cm3
c. 5g/cm3
d. 20g/cm3
Objects float because…
a.They are more dense than water
b.They are less dense than water
c.They have more buoyant force than the
water
d.Everything floats
A student added a small ball to a graduated
cylinder containing 10 milliliters of water.
What is the volume of the ball?
A 5 mL
B 10 mL
C 15 mL
D 20 mL
A student divides several cubes into two
groups, based on whether or not each cube
can float in water. What property is the
student using to classify the cubes?
A weight
B density
C conductivity
D mass
Which physical property of matter describes the
ability of a substance to transfer heat and
electricity?
a. Solubility
b. Conductivity
c. Malleability
d. Density
Using the density column and the data table
shown, which of the samples will probably
float on top of the oil?
A.Sample C
B.Sample B
C.Sample A
D.Sample D
Which physical property of matter describes a
substance’s ability to dissolve in another
substance?
a. Density
b. ductility
c. Malleability
d. solubility
Which physical property of matter describes
metal’s ability to be pounded and shaped?
a. Density
c. Ductility
b. Malleability
d. Solubility
Which of the following describes a chemical
property of matter
a.Sodium is highly reactive with water
b.An ice cube melts when placed in the sun
c.Water boils at 100◦C
d.The density of water is 1g/mL
What two quantities must be known to
calculate the density of a sample of matter?
A. Color and mass
B. Mass and volume
C. Length and mass
D. Solubility and mass
Identify the following properties as physical
or chemical properties
Magnetism
Reactivity
Density
Boiling Point
Size
Texture
Malleability
Freezing point
Combustibility
Ductility
Odor
Volume
Flammability
Solubility
e. Distinguish between changes in matter as
physical (i.e., physical change) or chemical
(development of a gas, formation of
precipitate, and change in color).
Physical Changes
• A change that affects one or more
physical properties of a substance
• Does Not form new substances
Examples
•
•
•
•
•
bending (nail)
crushing (can)
cutting (paper)
dissolving (sugar)
freezing (ice)
•
•
•
•
•
melting (butter)
molding (clay)
pounding (metal)
mixing (kool-aid)
sanding (wood)
Chemical Changes
• The process by which one or more
substances actually change into entirely
new substances with different properties
• Involve chemical reactions
• Hard to reverse
Evidence of changes
•
•
•
•
•
•
A new substance is formed
Change in odor (sour milk)
Change in color (jewelry, copper dome)
Production of heat (exothermic) (hand warmer)
Absorption of heat (endothermic) (cool pack)
Fizzing, foaming, bubbles (release of gas)
(effervescent tablets)
• Release of sound or light (fireworks)
• Forms a precipitate (a solid from solutions)
Examples of Chemical Changes:
• Leaves changing color in fall
• Alka-Seltzer Tablet in water
• A candle burning
• A cake/bread baking
• Toasting bread
• Digesting food
• Metal rusting
• Silver tarnishing
• Copper tarnishing (Statue of Liberty)
• A battery working
• Roasting marshmallows
• Frying an egg
Mini Review
Which is an example of a chemical change?
a. Ice melting
b. lava cooling
c. Wood being chopped
d. iron rusting
Why would dissolving salt in water be
considered a physical change?
a. The salt disappears forever.
b. A new substance is produced.
c. The salt changes its state.
d. The salt keeps its identity.
During physical changes, matter always retains
its
a. size.
c. state.
b. identity.
d. texture.
Which of the following is a characteristic of ALL
chemical changes?
A. A different state of matter is produced
B. Some mass is converted to energy
C. Some form of light is given off
D. A new material is formed
A student mixes two clear liquids in a flask. A
moment later a white solid forms at the
bottom of the flask. What can the student
conclude?
a.A physical change occurred
b.A chemical change occurred
c.No new substances have formed
d.A mixture has been created
Which of the following statements best
supports the idea that a chemical reaction is
occurring when baking soda is combined with
vinegar?
A.The baking soda disappears
B.Gas is produced.
C.Two different substances are combined.
D.The substances no longer look the same.
All of the following are signs of a chemical
reaction except
A. color change
B. development of a gas
C. formation of precipitate
D. change in state
When making cookies, which process involves a
chemical change?
A. Mixing the sugar and the flour
B. Rolling out the dough
C. Cutting the dough with cookie cutters
D. Baking the dough
Let’s Practice—Decide whether each change is
physical or chemical
Melting chocolate
Baking a cake
Burning a match
Adding kool-aid mix to water
Crushing a pill
Evaporating water
Digesting food
Making Jello
Burning gas in a car
Using a cookie cutter to cut cookie dough
Baking cookies
The Statue of Liberty oxidizing
Molding play-dough
Leaves changing color in the fall
Metal rusting
Silver tarnishing
Turning water into ice
Cracking an egg
A battery working
Frying an egg
f. Recognize that there are more than 100
elements and some have similar properties
as shown on the Periodic Table of Elements.
• Elements in a family or group have similar
properties
• They have similar properties because they
have the same number of electrons in their
outer energy level
A Column of
elements is called a
group or family
A row of elements is
called a period (think:
a period goes at the
end of a sentence)
Elements are classified as metals, nonmetals,
and metalloids
Metals
• Most elements are metals
• Are found to the left of the zigzag line
• Most are solid at room temperature
• Most are shiny and good conductors
• Malleable—can be flattened
•Ductile—can be drawn into wires
Nonmetals
• Right of the zigzag line on the periodic table
• Elements in group 18 (Noble Gases) have a complete
set of electrons in their outer level
• More than ½ are gases at room temperature
• Many nonmetal properties are the opposite of
properties of metal
Metalloids
• Also called semiconductors
• Border the zigzag line on the periodic table
• Have some properties of metal and some of
nonmetals
Mini Review
What do the elements sulfur (S), nitrogen (N),
phosphorus (P), and bromine (Br) have in
common?
A They are noble (inert) gases
B They are nonmetals
C They have the same thermal conductivity
D They have the same number of protons
The elements highlighted in the picture above
are members of which group?
A. Alkali metals
B. Alkaline Earth metals
C. The Halogens
D. The Noble Gases
The elements in this group are
A. Highly reactive
B. Somewhat reactive
C. Non reactive
In which region of the table would nonmetals
be found?
A1
B2
C3
D4
Each element on the periodic table has its own
unique type of
A. atom
B. molecule
C. compound
D. electron
The columns highlighted on the periodic table
above are called
A. Periods
B. Groups or Families
C. Transition Columns D. Periodic Columns
What forms when atoms bond?
A. molecules and compounds
B. Electrons and protons
C. groups or families
D. periods or rows
Which class of elements best conducts
electricity?
A metals B nonmetals C metalloids
Which element is represented in the
6
C
square
above?
12.0
A. Calcium
B. Carbon
C. Chlorine
D. Cesium
What does the number 6 represent?
A. the element’s atomic number
B. the element’s atomic mass
C. the number of neutrons
D. the number of protons and neutrons
Which of the following atoms would be most
likely to form chemical bonds?
The element fluorine (F) is a very reactive non
metal with 7 valence electrons. Which other
element shares these properties?
A. oxygen (O)
B. sulfur (S)
C. silver (Ag)
D. iodine (I)
What can group/family numbers on the
periodic table help you determine?
a. the number of valence electrons
b. the number of protons
c. the number of electrons
d. the number of neutrons
Which of the elements is most metallic?
A. Titanium (Ti)
B. Germanium (Ge)
C. Bromine (Br)
Which area includes an element that is a gas
at room temperature?
A. Area 1
B. Area 2
C. Area 3
g. Identify and demonstrate the Law of
Conservation of Matter.
Law of Conservation of Mass/Matter—
states that mass is neither created nor
destroyed in ordinary chemical and physical
changes
• Atoms are not lost or gained in a chemical
reaction—just rearranged
• The mass of the reactants will equal the
mass of the products
• A chemical equation must
show the same numbers and
kinds of atoms on both sides
of the arrow (it must be balanced)
Mini Review
The chemical formula for water is always H2O.
What is the ratio of hydrogen to oxygen in a
molecule of water?
a. 1:1
b. 1:2
c. 2:1
d. 2:2
Which is the product in this chemical
formula?
N + O2 → NO2
a. N, O2
b. O2
c. O
d. NO2
How many atoms of oxygen must have been
present in the reactant of the equation
below?
a. 1
?  CO2
b. 2
c. 3
d. 4
In the equation below, how many atoms of
hydrogen are present in the reactants?
a. 1
b. 2
c. 3
d. 4
How many atoms of oxygen are in the
reactants?
a. 1
b. 2
c. 3
d. 4
What should the mass be after the reaction
takes place?
a. 299.23g
b. 300.23g
c. 325.23g
d. 400.23g
What does the Law of Conservation of Matter
state?
A. The total mass of the reactants is greater
than the total mass of the products
B. The total mass of the reactants is less than
the total mass of the products
C. The total mass of the reactants equals the
total mass of the products
D. Matter cannot change form
10/3/11
Cu + CO2  CuCO2
40g
?
100g
What must be the missing mass?
a. 40g
b. 50g
c. 60g
d. 100g
Tina combined 25 grams of vinegar and 25
grams of baking soda in a sealed plastic bag and
watch a chemical reaction take place.
What should the mass be after the reaction?
A. 50 grams
B. 75 grams
C. 100 grams
D. 125 grams