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States of Matter
• States of Matter: Materials can be classified as solids, liquids, or gases based on whether their shapes and volumes are definite or variable.
Definite*
• Definite: the shape and volume of a material won’t change when you move it• Definite does not mean it will
never change• Almost all solids have a closely
packed atomic arrangement
Liquids
• Liquid: the state of matter in which a material has a definite volume, but not a definite shape
Liquid
• Liquid: takes the shape of the container it is in• It does not change its
volume to fit the container
Gases
•Gas: a state of matter in which a material has neither a definite shape nor a definite volume
Read the paragraph about gas
• Gas: more space between atoms• Gas can be compressed into
smaller spaces• Gas spreads out when
released from compaction
Other states of matter
•Almost all matter on Earth is solid, liquid, or gas.•99 % of the universe matter
at high temperatures is in the form of plasma
Directions• Look back at your notes and
the book and tell whether each state has definite volume, definite shape, variable volume, or variable shape.
Kinetic Theory
•Kinetic energy: is the energy an object has due to its motion (comes from the Greek word “to move”)
Kinetic Theory
• The faster an object moves, the greater the kinetic energy is.• A baseball thrown at 85 mph has
more kinetic energy than one thrown at 75 mph• The kinetic theory suggests that
the materials in the ball are moving too
Motion in gases
•At room temperature, the average speed of particles of gas is 1600 kilometers per hour–994 mph!
Look on page 72
• Two helium atoms bounce around the jar.• They collide with each other and
the jar.• One may lose speed while the
other gains speed.• The total energy remains the
same!
Attraction ;-)
• There are forces of attraction among the particles in all matter.• The faster the particles are
moving (like in gas) these forces of attraction are not as strong
Kinetic Theory of Gases
• The constant motion of particles in a gas allows a gas to fill a container of any shape or size.
Kinetic Theory of Gases 3 Points
• 1: Particles in a gas are in constant, random motion• 2. The motion of one particle is
unaffected by the motion of the other particles unless the particles collide.• 3. Forces of attraction among particles in
a gas can be ignored under ordinary conditions.
Air Freshener
• We will divide into groups• Groups will go to different corners of the room• I will spray the air freshener in a far corner of
the room and we will see how long it takes for the gas particles to travel to each corner
Behavior of Liquids
•Mass of an element can have an effect on movement•Mercury (which is a liquid at
room temperature) has 50 times the mass of a helium atom
Behavior of a liquid
• The arrangement of the atoms has an effect on movement• The particles of a liquid are much
closer together than particles of a gas–This makes the power of
attraction much greater
Behavior of Liquids
• A liquid takes the shape of its container because particles in a liquid can flow to new locations.• The volume of a liquid is constant
because forces of attraction keep the particles close together
Behavior of Solids
• Solids have definite shape and definite volume because particles in a solid vibrate around fixed locations
Quick assessment
• Write at least two paragraphs (5-7 complete sentences each paragraph) explaining how the kinetic theory can be used to explain the general characteristics of solids, liquids, and gases.
• This will be graded as a quiz ;-)
SI Units
• Pressure = Force/Area• Force is measure in newtons (N)• Area is measured in m2
• The SI unit for pressure is the pascal (Pa)
• Pa=N/m2
Factors that affect gas pressure
• Factors that affect the pressure of an enclosed gas are its temperature, its volume, and the number of its particles
Temperature
• Raising the temperature of a gas will increase its pressure if the volume of the gas and the number of particles are constant• Think of a car tire on the road
Volume
• Reducing the volume of a gas increases its pressure if the temperature of the gas and the number of particles are constant.• Empty plastic bottle
Number of particles
• Increasing the number of particles will increase the pressure of a gas if the temperature and the volume are constant
Complete your workbook up to number 18 on page 26.
Complete the section assessment on page 74 in your book
Due tomorrow