Matter

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Matter

• Ch 2-3

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Matter

• Matter anything that has mass and takes up space
• Chemistry the scientific study of the
  composition, structure, and properties of matter
  and the changes that matter undergoes

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Composition of Matter

• Atoms are matter
• Element substance that cannot be separated or
  broken down into simpler substances by chemical
  means
• Atom the smallest unit of an element that
  maintains the properties of that element

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Composition of Matter

• Elements combine to form a compound
• Compound Substance made of atoms of two or more
  different elements that are chemically combined
• Compounds have unique properties

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Composition of Matter

• Molecule smallest unit of a substance that keeps
  all of the physical and chemical properties of
  that substance
• A molecule acts as a unit
• Atoms join together and make millions of molecules

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Composition of Matter

• Chemical formulas represent compounds and
  molecules
• Chemical Formula combination of chemical symbols
  and numbers to represent a substance
• C6H12O6 H2O CO CO2

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Pure Substances and Mixtures

• Pure Substance sample of matter, either single
  element or single compound, that has definite
  chemical and physical properties
• Cannot be separated in the means a mixture can be
  separated
• Mixture combination of two or more substances
  that are not chemically combined

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Pure Substances and Mixtures

• Mixtures are formed by mixing pure substances
• Mixtures are classified by how thoroughly the
  substances mix
• Heterogeneous mixture substances that are not
  mixed uniformly and are not evenly distributed
• Homogenous Mixture components are evenly
  distributed and the mixture is the same throughout

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Pure Substances and Mixtures

• Miscible will dissolve into different liquids
• Gasoline made of 100 different liquids
• Immiscible will not mix together and form
  different layers
• Oil and Water

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Pure Substances and Mixtures

• Gases can mix with liquids
• Air is a mixture of gases
• Soda pop is a mixture of carbon dioxide and sugar
  water
• Lava molten rock can contain large amounts of
  gases
• Pumice is formed from violent separation of gases
  from magma

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Properties of Matter

• Properties of matter such as color and shape are
  called physical properties
• Physical properties are easy to observe and
  describe matter
• They remain constant for pure substances
• Mass, Volume, and density are physical properties

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Properties of Matter

• Hardness, resistance to breakage, and ability to
  dissolve in water are also physical properties
• Melting point temperature and pressure at which
  a solid becomes a liquid
• Boiling point temperature and pressure at which
  a liquid becomes a gas

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Density

• Density is a physical property
• Density is measurement of how much matter is
  contained in a certain volume of a substance
• Substance with low density is light, high
  density is heavy
• Density mass/Volume or D m/V
• Units for density are g/cm3 or g/mL

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Practice

• A piece of tin has a mass of 16.52 g and a volume
  of 2.26 cm3. What is the density of the tin?
• A piece of metal has a density of 11.3 g/cm3 and
  a volume of 6.7cm3. What is the mass of the
  piece of metal?
• If 10 mL of ice has a mass of 9.17g, what is the
  density of ice?

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Chemical Properties

• Chemical properties describe how a substance
  reacts and changes into a new substance
• Chemical properties are generally not as easy to
  observe as physical properties
• Evidence of change production of heat or light,
  appearance of gas bubbles, formation of a solid

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Chemical Properties

• Reactivity the ability of a substance to combine
  chemically with another substance
• Flammability the ability of a substance to react
  in the presence of oxygen and burn when exposed
  to a flame
• A substance always has its chemical properties
  even if you cannot observe them

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Chemical v Physics Property

• You can observe a physical property without
  changing the substance, but you can only observe
  chemical properties when the identity of the
  substance is changing
• Iron is malleable ? what is malleable?
• Iron reacts with oxygen to form what?
• Physical and Chemical properties helps to
  identify and classify substances

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Changes in Matter

• A physical change affects one or more physical
  properties of a substance without changing its
  identity
• Breaking a piece of chalk in two.
• Dissolving is a physical change
• Salt or sugar into water
• Changing states is a physical change

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Changes in Matter

• Mixtures can be physically separated because they
  are not chemically combined
• Italian Dressing
• Oil and water
• Chemical changes occurs when a substance changes
  its composition by forming new substances

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Changes in Matter

• Chemical changes happen everywhere
• Batteries die, cars rust, fruit ripen, baking a
  cake
• New substances that form from chemical properties
  cannot be reversed by physical changes

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Changes in Matter

• Compounds can be broken down through chemical
  changes
• Some compounds can be broken down into elements
• Some compounds are broken down into simpler
  compounds

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Kinetic Molecular Theory

• All matter is made of atoms and molecules
• These particles are always in motion (higher
  temperature faster movement)
• At the same temperature, more massive particles
  move slower then less massive particles

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Phases of Matter

• Solid ? definite shape and definite volume,
  closely packed molecules
• Molecules move slightly but dont change position
• Crystal an orderly arrangement of molecules
  (salt, diamond)
• Amorphours molecules in no particular order
  (rubber, wax)

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Phases of Matter

• Liquid ? definite volume, but no definite shape
• Particles easily slide over each other
• Particles are close together

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Phases of Matter

• Gas ? no definite volume, no definite shape
• Expands to fill whatever space is available
• Particles move rapidly
• Plasma ? no definite shape, particles broken
  apart
• Most common (stars, sun, lighting, fire)
• Conduct electricity

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Changes of State

• Temperature a measure of the energy of molecules
• Changes of State (Fig 8 p 74)
• Solid to liquid ? melting
• Liquid to Gas ? Evaporation
• Gas to Liquid ? Condensation
• Liquid to Solid ? Freezing
• Solid to Gas ? Sublimation

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Conservation of Mass and Energy

• Mass and energy cannot be created or destroyed
• In both chemical and physical changes, the total
  mass of matter stays the same before and after
  the change
• Energy cannot be created or destroyed
• Energy is converted from one form to another
  during a physical or chemical change

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Fluids

• Substance where the particles can flow (gas or
  liquid)
• Air, water
• Buoyant Force
• The upward force exerted on an object in a fluid
• When you float in a swimming pool on a tube, the
  buoyant force keeps you and the tube afloat

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Pressure

• The amount of force exerted per unit of area on a
  surface
• Pressure (Pa) Force (N) / Area (m2)
• Pa N/ m2
• All fluids exert pressure, pressure increases and
  depths increases

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Pressure

• Archimedes Principle
• The buoyant force on an object is equal to the
  weight of the fluid that is displaced
• Pascals Principle
• A fluid in equilibrium contained in a vessel
  exerts a pressure of equal intensity in all
  directions

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Pascals Principal

• P1 P2
• F1/A1 F2/A2
• Practice
• A hydraulic lift, lifts a 19, 000 N car. If the
  area of the small piston equals 10.5 cm2 and the
  area of the large piston equals 400 cm2, what
  force needs to be exerted on the small piston to
  lift the car?

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Properties of Gases

• No definite shape or volume
• Expands to fill the container
• Fluids
• Constant motion, frequently collide
• Low density (molecules far apart, mostly empty
  space)
• Compressible
• Mix easily with one another

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Gas Laws

• Boyles Law
• If the temperature of a gas is kept constant, the
  volume of the gas increases as the pressure of
  the gas decreases
• Indirect relationship
• P1V1 P2V2

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Boyles Law

• Balloons released into the atmosphere eventually
  explode because their volume increases as they
  rise (pressure decreases).
• The balloon can no longer expand with the
  increasing volume and break

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Charles's Law

• If a gas is kept at a constant pressure, the
  volume of the gas increases as the temperature of
  the gas increases
• Direct relationship
• V1/ T1 V2/ T2

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Charles Law

• Helium Balloons deflate when they are taken
  outside in cold weather and inflate when they are
  taken into warmer temperature
• Basketballs deflate when they are taken outside
  in cold weather, but they inflate when they are
  brought back inside

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Gay-Lussac Law

• If the volume of a gas is kept constant, the
  temperature will increase as the pressure
  increases
• Direct relationship
• P1/ T1 P2 / T2

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Gay-Lussacs Law

• Aerosol cans have a fixed volume. When the can
  is exposed to heat as a flame, the gas pressure
  inside the can increase with the increasing
  temperature, the can will explode once the
  pressure is too great for the can to hold.