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Transcript
States of Matter
States of Matter Notes
• There are four states of matter: solid,
liquid, gas, plasma.
States of Matter
Solids
• The particles of a solid are arranged in a definite
pattern; thus, a solid has both a definite shape
and a definite volume.
• Solids are substances with densely packed
particles. These particles may be ions, atoms, or
molecules.
• Solids that have no crystal patterns are called
glasses.
States of Matter
Solids and Liquids
• The atoms in solids vibrate close together at any
temperature above absolute zero (2273°C).
• The atoms in a liquid can then slide past each
other.
• While liquids have a definite volume, they take the
shape of their container.
States of Matter
Gases
• In gases, the particles are separated by relatively
large distances and move about at extremely
hibgh speeds.
• Gas particles move freely and independently of
each other and travel randomly.
• Gases have no definite shape or volume and
can expand into any space available, unless
they are restrained.
• Earth’s gravity keeps the gases in the atmosphere
from escaping into space.
States of Matter
Gases
• Individual particles in a liquid may gain sufficient
energy to escape the liquid.
• Evaporation, or vaporization, is the process of
changing from a liquid to a gas.
• When any liquid reaches its boiling point, it
vaporizes quickly and becomes a gas.
• Sublimation is the slow change of state from a
solid to a gas without an intermediate liquid state.
States of Matter
Plasma
• At temperatures greater than 5000°C, the
collisions between particles are so violent that
electrons are knocked away from atoms.
• Such extremely high temperatures exist in stars,
and, as a result, the gases of stars consist
entirely of positive ions and free electrons.
• Plasmas are hot, highly ionized, electrically
conducting gases.
• Plasmas can be found in neon tubes, lightening
and the stars, including the sun!
States of Matter
Changes of State
• Solids melt when they absorb thermal energy and
their temperatures rise.
• When a liquid absorbs thermal energy from the
environment, it evaporates.
• When a liquid freezes, the same thermal energy
is then released back into the environment.
• When a gas is cooled, it releases thermal energy
in the process of condensation.
• Condensation is the change from a gas to
a liquid.
Thermal Energy
____ ice melts
____ water vapor condenses to form rain
____ water freezes to make ice
____ water evaporates from a glass
States of Matter
Conservation of Matter and Energy
• The law of conservation of matter states that
“Matter cannot be created or destroyed but
can change from one form to another.”
• The law of the conservation of energy, also called
the first law of thermodynamics, states that
energy cannot be created or destroyed but it can
be changed from one form to another.
States of Matter
Section Assessment
1. Match the following terms with their definitions.
___
C crystalline structure A. solids that consist of densely
packed atoms arranged at
___
A glasses
random
___
D evaporation
B. a slow change from a solid
___
B sublimation
to a vapor without an
intermediate liquid state
C. a solid in which the particles
are arranged in regular
geometric patterns
D. the process of change from
a liquid to a gas
States of Matter
Section Assessment
3. Identify whether the following processes absorb
or release energy into the environment.
___
B condensation
A. Absorb energy
___
A evaporation
B. Release energy
___
A melting
C. Neither release
or absorb
___
B freezing
___
A sublimation
What are elements?
Matter
• The physical world that surrounds you and all
living things are composed of matter.
• Matter is anything that has volume and mass.
• On Earth, matter usually can be found as a solid,
liquid, or gas.
• All matter is made up of elements.
What are elements?
What are Elements?
• An element is a substance that cannot be broken
down into simpler substances by physical or
chemical means.
• Currently there are 118 elements on the periodic
table.
• Ninety-two elements occur naturally on Earth
and in the stars.
• The other elements have been produced in
laboratory experiments.
What are elements?
Elements
• Each element is identified by a one-, two-,
or three-letter abbreviation known as a
chemical symbol.
What are elements?
What Elements are Most Abundant?
• Silicon and oxygen make up 75% of earth’s crust.
• Al, Fe, Ca, Na, K, and Mg are also found.
What are elements?
Elements are Made of Atoms
• Each element has distinct characteristics.
• An atom is the smallest particle of an element
that has all of the characteristics of that element.
• All atoms consist of even smaller particles:
protons, neutrons, and electrons.
What are elements?
Elements are Made of Atoms
• The nucleus, which is made up of protons and
neutrons, forms the center of an atom.
– A proton (p+) is a tiny particle that has mass and a
positive electrical charge.
– A neutron (n0) is a particle with about the same mass
as a proton, but it is electrically neutral; that is, it has
no electrical charge.
– Electrons (e-) are located outside the nucleus and
have a negative charge.
• All atomic nuclei have a positive charge.
An atom of Helium
Atomic Number of 2
Atomic Mass of 4
-2 protons
-2 electrons
(To find neutrons-
Mass-Atomic #)
4-2=2!
-2 neutrons
What are elements?
Elements are Made of Atoms
• The number of protons and neutrons in different
atoms varies widely.
– The mass number is the total number of protons
and neutrons. It is the bottom number.
– The atomic number is the number of protons only in
an atom’s nucleus. This is the top number.
– The number of protons is ALWAYS equal to the
number of electrons.
– You find the number of neutrons by subtracting the
number of protons from the mass number.
Chlorine
Atomic
Number
4
Mass
# of
Pros
9
4
45
21
65
# of
# of
Element
Neutrons Electrons Symbol
5
4
Be
31
Ga
30
20
Ca
24
12
37
W
49
What are elements?
Elements are Made of Atoms
• An energy level represents the area in an atom
where an electron is most likely to be found.
• The mass of an atom depends mostly upon the
number of protons and neutrons in its nucleus.
• The size of an atom
depends upon the
number and
arrangement of
its electrons.
What are elements?
Electrons in Energy Levels
• Electrons are distributed over one or more
energy levels in a predictable pattern.
• Each energy level can hold only a limited
number of electrons.
– The innermost energy level can hold only 2 electrons.
– The second energy level can hold up to 8 electrons.
– The third energy level can hold up to 18 electrons.
– The fourth energy level can hold up to 32 electrons.
• Electrons tend to occupy the lowest available
energy level.
What are elements?
Isotopes
• The number of neutrons in the nuclei of an
element’s atoms can vary.
• Isotopes are atoms of the same element that
have different mass numbers and the same
chemical properties.
• The atomic mass
of an element is the
average of the
mass numbers of
the isotopes of an
element.
What are elements?
Isotopes
• The nuclei of some isotopes are unstable and
release radiation.
• Radioactivity is the spontaneous process
through which unstable nuclei emit radiation.
• During radioactive decay, a nucleus can lose
protons and neutrons, change a proton to a
neutron, or change a neutron to a proton.
• Because the number of protons in a nucleus
identifies an element, decay changes the
identity of an element.
What are elements?
Section Assessment
1. Match the following terms with their definitions.
___
A proton
___
D energy level
___
C neutron
___
B atom
A. a tiny particle that has
mass and a positive
electrical charge
B. the smallest particle of an
element that has all of the
characteristics of that element
C. a tiny particle that has mass
and is electrically neutral
D. an area of an atom where
an electron is most likely to
be found
How Atoms Combine
Compounds
• A compound is a substance that is composed of
atoms of two or more different elements that are
chemically combined. (Ex. H2O)
• Most compounds have totally different properties
from the elements of which they are composed.
• For most elements, an atom is chemically stable
when its outermost energy level is full.
• Chemical bonds are the forces that hold the
elements together in a compound creating a
state of stability.
How Atoms Combine
Compounds
Covalent Bonds
– One way in which atoms fill their outermost energy
levels is by sharing electrons.
– A covalent bond is the attraction of two atoms for a
shared pair of electrons that holds the atoms together.
How Atoms Combine
Compounds
– A molecule is composed of two or more atoms held
together by covalent bonds.
– Molecules have no overall electrical charge because
the total number of electrons equals the total number
of protons.
How Atoms Combine
Ions
• Sometimes, atoms gain or lose electrons from
their outermost energy levels.
• A charged particle called an ion is an atom that
gains or loses an electron.
• In general, an atom in which the outermost
energy level is less than half-full tends to lose its
valence electrons.
• When an atom loses its valence electrons, it
becomes positively charged and is indicated by
a superscript plus sign.
How Atoms Combine
Ions
• An atom in which the outermost energy level is
more than half-full tends to fill its outermost energy
level by adding one or more needed electrons.
• Such an atom forms a negative ion which is
indicated by a superscript negative sign.
• If the outermost energy level is exactly half-full,
an atom may form either a positive or
negative ion.
How Atoms Combine
Ions
Ionic Bonds
– Positive and negative ions attract each other.
– An ionic bond is the attractive force between two
ions of opposite charge.
– Positive ions are always written first in
chemical formulas.
How Atoms Combine
Metallic Bonds
• In metals, the valence electrons are shared by
all the atoms, in a metallic bond.
How Atoms Combine
Chemical Reactions
• Sometimes, compounds break down into
simpler substances.
• A chemical reaction is the change of one or
more substances into other substances.
• Chemical reactions are described by
chemical equations.
How Atoms Combine
Mixtures and Solutions
• A mixture is a combination of two or more
components that retain their identities.
• When a mixture’s components are easily
recognizable, such as soil, it is called a
heterogeneous mixture. (Ex. Bag of M & Ms)
• In a homogeneous mixture such as coffee, the
component particles cannot be distinguished, even
though they still retain their original properties.
How Atoms Combine
Mixtures and Solutions
• A homogeneous mixture is also called a solution.
• A solution may be liquid, gaseous, or solid.
– Seawater is a liquid solution consisting of water
molecules and ions of many elements that exist
on Earth.
– Air is a solution of gases, mostly nitrogen and oxygen
molecules together with other atoms and molecules.
– Bronze is a solid solution of copper and tin atoms.
How Atoms Combine
Mixtures and Solutions
Acids and Bases
– Many chemical reactions that occur on Earth involve
solutions called acids and bases.
– An acid is a solution containing a substance that
produces hydrogen ions (H+) in water.
– The most common acid in our environment is carbonic
acid, which is produced when carbon dioxide is
dissolved in water by the following reaction.
H2O + CO2  H2CO3
pH Scale
How Atoms Combine
Mixtures and Solutions
Acids and Bases
– The pH scale measures the hydrogen and
hydroxide ions in solutions on a scale of 0 to 14,
with 7 being neutral.
– A solution with a pH reading below 7 is considered
to be acidic.
– A solution with a reading above 7 is considered to
be basic.
How Atoms Combine
Section Assessment
1. Match the following terms with their definitions.
___
C covalent bond A. an atom that gains or loses an
___
D compound
___
A ion
___
B acid
electron and becomes electrically
charged
B. a solution containing a substance
that produces hydrogen ions in water
C. an attraction of two atoms for a
shared pair of electrons that hold the
atoms together
D. a substance that is composed of
atoms of two or more different
elements that are chemically
combined
How Atoms Combine
Section Assessment
2. Identify whether the following are acidic, basic,
or neutral.
A Milk
___
A. Acidic
C Distilled water
___
B. Basic
A Rainwater
___
C. Neutral
B Ammonia
___
A Lemon
___
A Tomato
___
B Antacid
___
Chapter Resources Menu
Study Guide
Section 3.1
Section 3.2
Section 3.3
Chapter Assessment
Image Bank
Section 3.1 Study Guide
Section 3.1 Main Ideas
• The basic building blocks of matter are atoms. Atoms consist
of protons, neutrons, and electrons.
• Protons have a positive electrical charge, electrons have a
negative electrical charge, and neutrons are electrically
neutral. Protons and neutrons make up the nucleus of an
atom; electrons surround the nucleus in energy levels.
• An element is a substance consisting of atoms with a specific
number of protons in their nuclei. Isotopes of an element differ
by the number of neutrons in their nuclei. Many elements are
mixtures of isotopes.
• The number of electrons in the outermost energy levels of
atoms determines their chemical behavior. Elements with the
same number of electrons in their outermost energy levels
have similar chemical properties.
Section 3.2 Study Guide
Section 3.2 Main Ideas
• Atoms of different elements combine to form compounds.
• Atoms held together by the sharing of electrons in covalent
bonds form molecular compounds.
• Ions are electrically charged atoms or groups of atoms.
Positive and negative ions attract each other and form ionic
compounds.
• Acids are solutions containing hydrogen ions. Bases are
solutions containing hydroxide ions. Acids and bases can
neutralize each other.
• A mixture is a combination of components that retain their
identities. A solution is a mixture in which the components can
no longer be distinguished as separate. Solutions can be
liquid, solid, gaseous, or combinations.
Section 3.3 Study Guide
Section 3.3 Main Ideas
• Matter on Earth exists in three common physical states: solid,
liquid, or gaseous. Matter in the universe includes plasma.
• Most solids have a crystalline structure.
• Liquids are densely packed arrangements of particles.
• Gases consist of widely separated, individual particles.
Plasmas are hot, highly ionized, electrically conducting gases.
• Changes of state involve thermal energy.
Chapter Assessment
Multiple Choice
1. Which of the following is NOT about elements?
a. They cannot be broken down into simpler
substances by physical or chemical means.
b. There are 47 naturally occurring elements
on Earth and in the stars.
c. All matter is made of elements.
d. Each element is identified by a
chemical symbol.
There are 92 elements that occur naturally on Earth and
in the stars.
Chapter Assessment
Multiple Choice
2. An element’s atomic number represents ____.
a. the number of protons in the atom’s nucleus
b. the combined number of protons and neutrons
in the atom’s nucleus
c. the number of neutrons in the atom’s nucleus
d. none of the above
The combined number of protons and neutrons is the
element’s mass number. The number of neutrons can
vary among the atoms of an element, creating isotopes.
Chapter Assessment
Multiple Choice
3. Which is the most abundant element in
the universe?
a. oxygen
c. iron
b. helium
d. hydrogen
Hydrogen makes up about 93.5% of all matter in the
universe. It is followed by helium at 6.3%.
Chapter Assessment
Multiple Choice
4. Which is the most abundant element in
Earth’s crust?
a. hydrogen
c. oxygen
b. silicon
d. aluminum
Oxygen makes up 46.65 of Earth’s crust. It is followed by
silicon (27.7%), aluminum (8.1%), and iron (5.0%).
Chapter Assessment
Multiple Choice
5. Which of the following is a molecule?
a. argon
c. nitrogen
b. water
d. uranium
Argon, nitrogen, and uranium are elements.
Chapter Assessment
Short Answer
6. What condition is necessary for matter to be in
a plasma state?
The temperature must be greater than
5000ºC. At temperatures this high, the
collisions between particles are so violent that
electrons are knocked away from atoms.
Chapter Assessment
Short Answer
7. What three forms can a solution take?
A solution may be liquid, gaseous, or solid.
Image Bank
Chapter 3 Images
Image Bank
Chapter 3 Images
Image Bank
Chapter 3 Images
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