Chapter 4 Elements, Compounds,

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Chapter 4 Elements, Compounds, Mixtures
Salt Fields
Gold
Granite
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Elements

• Are pure substances that cannot be separated into
  simpler substances by physical or chemical
  changes.
• Elements are found on the periodic table of
  elements

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Pure Substance

• Contains only one type of particle.
• Example 5 grams of the element gold is like all
  other particles of gold.
• The particles of a pure substance are alike no
  matter where that substance is found.

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Identifying Elements

• Physical properties and Chemical properties are
  ways in which you may identify an element.
• Examples of Physical Properties melting point,
  density, color, hardness, and texture.
• Examples of Chemical Properties flammability,
  reactivity with oxygen, acid water.

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Elements are Classified by their Properties

• Elements are divided into three categories
  Metals, Nonmetals, Metalloids.
• Elements are classified into groups according to
  their shared properties.
• Example Iron, Nickel Cobalt are all shiny and
  conduct electric current therefore scientists
  have grouped them into the metal section of the
  periodic table.

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Metals

• Are
• Shiny
• Good conductors of thermal energy
• Good conductors of electric current
• Malleable (hammered into sheets)
• Ductile (drawn into thin wires)
• Examples Copper, Lead, Tin

Copper
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Nonmetals

• Are
• Dull
• Poor conductors of thermal energy
• Poor conductors of electric current
• Brittle
• Unmalleable
• Examples Sulfur, Bromine, Neon

Sulfur
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Metalloids

• Are
• Have both properties of metals nonmetals
• Some are shiny some are dull
• Somewhat Malleable and ductile
• Some conduct thermal energy and electric current
  well
• Examples Silicon, Antimony, Boron

Silicon
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Compounds

• A pure substance composed of two or more elements
  that are chemically combined.
• In order for elements to combine they must react
  or undergo a chemical change with another.
• Examples
• Table salt- sodium and chlorine
• Water- hydrogen and oxygen
• Once the chemical change occurs you have another
  pure substance
• http//www.youtube.com/watch?v0evGDGkOMvc

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Compounds

• Each compound like elements has its own unique
  set of physical and chemical properties that
  helps you identify it.
• Example
• -boiling point
• -melting point
• -density
• -color
• -reactivity

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Compounds in Nature

• Proteins are compounds found in all living
  things.
• Nitrogen is needed to make proteins.
• Plants get their nitrogen compounds from the
  soil. Animals get the nitrogen they need by
  eating plants or animals that have eaten plants.

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Quiz

• 1. An element is a pure substance that cannot be
  _________ into other substances.
• combined C. made
• separated D. burned
• 2. Which two categories of elements are good
  conductors of electricity?
• Metals and Nonmentals c. Metals and some
  Metalloids
• Nonmetals and Metalloids d. Water and Metals
• 3. Elements are divided into three categories
• metals, nonmetals, metalloids
• metals, solids, liquids
• solids, liquids, gasses
• cobalt, iron, nickel

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Quiz Continued

• 4. Two or more elements that are chemically
  combined are called___________.
• metals C. pure substance
• elements D. compounds
• 5. True or False
• In order for elements to combine they must react
  or undergo a chemical change with another.

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Mixtures

• Are a combination of two or more substances that
  are not chemically combined.
• Two or more materials together form a mixture if
  they do not react to form a compound.
• Example A Pizza dough, sauce, pepperoni,
  cheese, olives. They do not react when put
  together.

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Mixtures continued

• Since no chemical change has occurred the
  substance still has the same chemical makeup it
  had before it was combined with the other
  substances.
• Mixtures can be physically separated. If you
  dont like olives on your pizza you may pick them
  off. This is a physical change of the pizza.

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Mixtures Continued

• Mixtures are not all as easy to separate. Salt
  water can be separated but you must separate the
  salt from the water by heating the mixture. The
  water changes from a liquid to a gas, and the
  salt remains.
• Other ways to separate mixtures
• - Distillation is a process that separates a
  mixture based on its boiling point. (saltwater)
• -Centrifuge separates according to the densities
  of the components. (blood)
• -Magnet can separate iron from aluminum.

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Mixtures vs. Compounds

• Mixtures
• 1. Are elements, compounds, or both.
• 2. Separated by physical means.
• 3. They keep original properties.

• Compounds
• 1. Are elements.
• 2. Lose their original properties.
• 3. Separated by chemical means.

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Solutions

• A mixture that appears to be a single substance
  but is composed of particles of two or more
  substances that are distributed evenly amongst
  each other.
• Example Saltwater

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Nerdy Science Joke of the day

• What did the compound say to the solution?

• Answer Youre all mixed up!

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Solute vs. Solvent

• In solutions the Solute is the substance that is
  dissolved.
• The Solvent is the substance in which the solute
  is dissolved.
• Example In saltwater salt is the solute or the
  substance that is dissolved. While water is the
  solvent which dissolves the salt.

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Solubility

• Is the amount of solute needed to make a
  saturated solution.
• If a solution contains all the solute it can hold
  at a given temperature it is saturated. An
  unsaturated solution contains less solute than it
  can hold at a given temperature.
• Mixing, Heating Crushing all affect how quickly
  solids will dissolve in liquids.

http//www.youtube.com/watch?v3G472AA3SEs
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Suspensions

• Are mixtures that have particles of a material
  throughout it. They settle to the bottom but do
  not dissolve.
• Example When you shake a snow globe, the snow
  moves around but eventually falls to the bottom.

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Nerdy Science Joke Alert!

• Settle Down!

• What did the chemist say to the suspension?

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Colloids

• Are mixtures in which
• particles are dispersed
• throughout but are not heavy enough to settle to
  the bottom. The particles are small and fairly
  well mixed.
• Example Jello is an example of a colloid.

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Quiz

• A mixture is a combination of ______ substance(s)
  that are not ______ combined.
• one, chemically C. two, chemically
• two, physically D. one, physically
• 2. True or False
• Mixtures can be physically separated.
• 3. The __________ is the substance that is
  dissolved, and the _________is the substance that
  dissolves.
• water, salt C. solvent, solute
• solute, solvent D. solution, water

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Quiz

• 4. Solubility is how much __________ can be
  dissolved.
• metal C. gas
• water D. solute
• 5. A snow globe is an example of a ______.
• colloid C. solvent
• suspension D. compound
• 6. A ________is a fairly well mixed mixture which
  the particles are not heavy enough to settle out.
  
• suspension C. solution
• colloid D. ratio