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- Matter is any substance that has mass and occupies volume.
- Matter exists in one of three physical state:
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- In a gas, the particles of matter are far apart and uniformly
distributed throughout the container.
- Gases have an indefinite shape and assume the shape of their container.
- Gases can be compressed and have an indefinite volume.
- Gases have the most energy of the three states of matter.
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- In a liquid, the particles of matter are loosely packed and are free to
move past one another.
- Liquids have an indefinite shape and assume the shape of their
container.
- Liquids cannot be compressed and have a definite volume.
- Liquids have less energy than gases but more energy than solids.
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- In a solid, the particles of matter are tightly packed together.
- Solids have a definite, fixed shape.
- Solids cannot be compressed and have a definite volume.
- Solids have the least energy of the three states of matter.
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- Most substances can exist as either a solid, liquid, or gas.
- Water exists as a solid below 0°C; as a liquid between 0°C and 100°C;
and as a gas above 100°C.
- A substance can change physical states as the temperature changes.
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- When a solid changes to a liquid, the phase change is called melting.
- A substance melts as the temperature increases.
- When a liquid changes to a solid, the phase change is called freezing.
- A substance freezes as the temperature decreases.
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- When a liquid changes to a gas, the phase change is called vaporization.
- A substance vaporizes as the temperature increases.
- When a gas changes to a liquid, the phase change is called condensation.
- A substance condenses as the temperature decreases.
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- When a solid changes directly to a gas, the phase change is called sublimation.
- A substance sublimes as the temperature increases.
- When a gas changes directly to a solid, the phase change is called deposition.
- A substance undergoes deposition as the temperature decreases.
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- Matter can be divided into two classes:
- Mixtures are composed of more than one substance and can be physically
separated into its component substances.
- Pure substances are composed of only one substance and cannot be
physically separated.
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- There are two types of mixtures:
- Homogeneous Mixtures
- Heterogeneous Mixtures
- Homogeneous mixtures have uniform properties throughout
- Saltwater is a homogeneous mixture
- Heterogeneous mixtures do not have uniform properties throughout
- Sand and water is a heterogeneous mixture
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- There are two types of pure substances:
- Compounds can be chemically separated into individual elements.
- Water is a compound that can be separated into hydrogen and oxygen.
- An element cannot be broken down further by chemical reactions.
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- There are over 100 elements that occur in nature. 81 of those elements
are stable.
- Only 10 elements account for 95% of the mass of the Earth’s crust:
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- Oxygen is the most common element in both the Earth’s crust and in the
Human body.
- While silicon is the second-most abundant element in the crust, carbon
is the second most abundant in the body.
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- Each element has a unique name.
- Names have several origins:
- Hydrogen is derived from Greek
- Carbon is derived from Latin
- Scandium is named for Scandinavia
- Nobelium is named for Alfred Nobel.
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- Each element is abbreviated using a chemical symbol.
- The symbols are 1 or 2 letters long.
- Most of the time, the symbol is derived from the name of the element.
- C is the symbol for carbon
- Cd is the symbol for cadmium
- When a symbol has a two letter symbol, the first is capitalized and the
second is lower case.
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- For some elements, the chemical symbol is derived from the original
Latin name.
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- Your first assignment:
- Module 1 Part B: This is a heads up! You must know (memorize if you
must) the following elements (name and symbol) by the time Exam 1 is
given. Please note that a periodic chart will be provided for every exam
which contains only the symbols, atomic numbers, and atomic masses.
Reference Table 4.3, page 79 of your text for most of the elements
listed below:
Elements: 1-38, 46-57, 74, 76-80, 82, 83, 86-89, 92 & 94
- For homework, you will practice the spelling of the elements at:
- http://www.hccfl.edu/faculty/john_taylor/elementquiz/elementnew.html
- A pretest quiz will be administered the first five minutes of the first
class of the second week of school. A hard copy of a sample quiz may be
obtained at:
- http://www.hccbrandon.net/chem1211/samptest/11M1b.htm
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- Elements can be divided into three classes:
- Metals
- Nonmetals
- Semimetals or metalloids
- Semimetals have properties midway between those of metals and nonmetals
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- Metals are typically solids with high melting points and high densities
and have a bright, metallic luster.
- Metals are good conductors of heat and electricity.
- Metals can be hammered into thin sheets and are said to be malleable.
- Metals can be drawn into fine wires and are said to be ductile.
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- Nonmetals typically have low melting points and low densities and have a
dull appearance.
- Nonmetals are poor conductors of heat and electricity.
- Nonmetals are not malleable or ductile and crush into a powder when
hammered.
- 11 nonmetals occur naturally in the gaseous state.
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- Each element is assigned a number to identify it. It is called the atomic number.
- Hydrogen is 1, Helium is 2, up to Uranium which is 92.
- The elements are arranged by atomic number on the periodic table.
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- Metals are on the left side of the periodic table, nonmetals are on the
right side, and the semimetals are in between.
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- Shown are the physical states of the elements at 25°C on the periodic
table.
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- The law of definite composition states that “Compounds always contain
the same elements in a constant proportion by mass”.
- Sodium chloride is always 39.3% sodium and 60.7% chlorine by mass, no
matter what its source.
- Water is always 11.2% hydrogen
and 88.8% oxygen by mass.
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- A particle composed of two or more nonmetal atoms is a molecule.
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- The number of each type of atom in a molecule is indicated with a
subscript in a chemical formula.
- If there is only one atom of a certain type, no ‘1’ us used.
- A molecule of the vitamin niacin has 6 carbon atoms, 6 hydrogen atoms, 2
nitrogen atoms, and 1 oxygen
atom. What is the chemical
formula?
- C6H6N2O
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- Some chemical formulas use parenthesis to clarify atomic composition.
- Antifreeze has chemical formula C2H4(OH)2. There are 2 carbon atoms, 4 hydrogen
atoms, and 2 OH units, giving a total of 6 hydrogen atoms and 2 oxygen
atoms.
- Antifreeze has a total of 10 atoms.
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- A physical property is a characteristic of a pure substance that we can
observe without changing its composition.
- Physical properties include appearance, melting and boiling point,
density, conductivity, and physical state
- A chemical property describes the chemical reactions of a pure
substance.
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- A physical change is a change where the chemical composition of the
substance is not changed.
- These include changes in physical state or shape of a pure substance.
- A chemical change is a chemical reaction.
- The composition of the substances changes during a chemical change.
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- Gas release (bubbles).
- Light or release of heat energy.
- Formation of a precipitate.
- A permanent color change.
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- Antoine Lavoisier found that the mass of substances before a chemical
change was always equal to the mass of substances after a chemical
change.
- This is the law of conservation of mass.
- Matter is not created or destroyed in physical or chemical processes.
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- If 1.0 grams of hydrogen combine with 8.0 grams of oxygen, 9.0 grams of
water is produced.
- Consequently, 3.0 grams of hydrogen combines with 24.0 grams of oxygen
to produce 27.0 grams of water.
- If 50.0 grams of water decomposes to produce 45.0 grams of oxygen, how
many grams of hydrogen are produced?
- 50.0 g water – 45.0 g oxygen = 5.0 g hydrogen
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- Potential energy, PE, is stored energy; it results from position or
composition.
- Kinetic energy, KE, is the energy matter has as a result of motion.
- Energy can be converted between the two types.
- A boulder at the top of the hill has potential energy; if you push it
down the hill, the potential energy is converted to kinetic energy.
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- All substances have kinetic energy no matter what physical state they
are in.
- Solids have the lowest kinetic energy, and gases have the greatest
kinetic energy.
- As you increase the temperature of a substance, its kinetic energy
increases.
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- Just like matter, energy cannot be created or destroyed but it can
converted from one form to another.
- This is the law of conservation of energy.
- There are six forms of energy: heat, light, electrical, mechanical,
chemical, and nuclear.
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- In a chemical change, energy is transformed from one form to
another. For example:
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- Mass and energy are related by Einstein’s theory of relativity, E = mc2.
- Mass and energy can be interchanged.
- The law of conservation of mass and energy states that the total mass
and energy of the universe is constant.
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- Matter exists in three physical states:
- Substances can be converted between the three states.
- Substances can be mixtures or pure substances.
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- Pure substances can be either compounds or elements.
- The elements are arranged in the periodic table.
- Each element has a name and a 1 or 2 letter symbol.
- Elements are classified as either metals, nonmetals, or semimetals.
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- A physical change is a change in physical state or shape.
- A chemical change is a change in the chemical composition of a
substance.
- Both mass and energy are conserved in chemical and physical changes.
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