Ch' 9 Elements, Compounds, and Mixtures

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Ch. 9 Elements, Compounds, and Mixtures
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Elements

• Pure Substance that cannot be separated into
  simpler substances by physical or chemical means

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• Pure Substance ? substance in which there is
  only one type of particle
• Example Every Atom in a 5g nugget of the
  Element Gold is identical to every other Atom of
  Gold

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• Each Element has its own Characteristic
  Properties
• -- these properties does not depend on amount of
  the Element present
• Physical Properties Boiling Point, Melting
  Point, Density, Color, Hardness,
• Chemical Properties Reactivity with Acid,
  Reactivity with Oxygen, Flammability

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3 Kinds of Elements

• Metal
• Has Luster
• Is Malleable
• Is Ductile
• Good Conductor of Heat and Electricity

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3 Kinds of Elements

• Non-Metals
• Has No Luster
• Not Malleable
• Not Ductile
• Not Good Conductor of Heat and Electricity

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3 Kinds of Elements

• Metalloid
• Also called Semi-Conductor
• Has Properties of Both Metals and Non-Metals

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98.5 Earths Crust comes from 8 Elements

• Oxygen 46.6
• Silicon 27.7
• Aluminum 8.1
• Iron 5.0
• Calcium 3.6
• Sodium 2.8
• Potassium 2.6
• Magnesium 2.1

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• Other 1.8 Titanium, Hydrogen, Carbon,
  Nitrogen, Copper, Zinc, Lithium, Nitrogen, Boron

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Earths Atmosphere

• Nitrogen 78
• Oxygen 21
• Other 1 is mixture of Argon, Water Vapor,
  Carbon Dioxide, Ozone, and other Gases
• --Has Changed Over Time

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Compounds

• Made of Elements
• Pure Substance composed of two or more Elements
  that are Chemically combined
• Majority of substances you see everyday

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Compounds

• Not All Elements will form Compounds
• Must have certain Ratio of each Element
• Example Water ( H20 )
• -- Two molecules of Hydrogen bond to One molecule
  of Oxygen

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• Compound Element
• Table Salt Sodium Chlorine
• Water Hydrogen Oxygen
• Vinegar Hydrogen Carbon
• Oxygen
• Carbon Carbon Oxygen
• Dioxide
• Baking Sodium Hydrogen
• Soda Carbon Oxygen

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Properties of Compounds

• Compound has properties that differ from those
  of the Elements that form it
• Sodium Chlorine ---? Sodium
• (reacts with (poisonous gas) Chloride
• water)
  (Table Salt)

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Breaking Down Compounds

• -- Compounds cannot be broken down by physical
  change
• -- The only way to break down a compound is
  through a chemical change
• Example Carbonic Acid breaks down into Carbon
  Dioxide and Water

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Breaking Down Compounds

• Will be broken down into Elements and Simpler
  Compounds
• Adding Energy (Break Apart Compound)
• Applying Heat
• Applying Electric Current

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Why Do We Need Break Down Compounds?

• Aluminum is Not found in
• Nature
• Comes from a Compound
• Aluminum Oxide

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Compounds in Nature

• All living organisms contain compound known as
  Protein
• Carbon Dioxide is another compound found in life

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Mixtures

• Combination of two or more substances that are
  not chemically combined
• Form as a result in a failure of forming a
  compound
• No Chemical Change (so each substance in a
  mixture has same chemical properties it had
  before the mixture formed)

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Examples

• Pizza easy to separate
• -- (cheese and tomato sauce do not combine)
• -- (easy to pick off mushrooms)
• Salt Water hard to separate
• -- Heat Mixture until water evaporates (Only Salt
  Left)

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Common Ways to Separate Mixtures

• Distillation ? process that separates a mixture
  based on Boiling Points of the component
• Examples
• Pure Water out of Salt Water
• Moonshine
• Gasoline and Kerosene out of Crude Oil

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Common Ways to Separate Mixtures

• Magnet ? attracted to Iron, Nickel, and Cobalt
• -- Used to separate nails that are made from Iron
  and Aluminum

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Common Ways to Separate Mixtures

• Centrifuge ? separates mixtures by the Densities
  of components
• Examples
• -- Mud Water Dirt
• -- Blood Plasma Red Blood
• Cells

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Mixtures

• Do not have a specific mass ratio like compounds
• Example
• -- Granite is mixture of 3 Minerals
• 1. Feldspar ? Pink
• 2. Mica ? Black
• 3. Quartz ? Colorless

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Solutions

• Homogenous mixture that appears to be a single
  substance
• Same appearance and properties throughout mixture

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• Dissolvinggt the process in which particles of
  substances separate and spread evenly throughout
  a mixture.
• Solutegtsubstance dissolved (salt)
• Solventgt substance in which the solute is
  dissolved. (water)

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• Solublegt able to dissolve
• Insolublegt unable to dissolve
• When two liquids or gases form a solution, the
  substance with the greater volume is the solvent.
• Water Salt in the winter. Salt is used to melt
  the snow and ice.
• Salt is used in a greater volume.

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• Alloys -- are solid solutions of metals or
  nonmetals dissolved in metals.
• Examples of alloys
• -Brass gt alloy of metal zinc dissolved in
  copper
• -Steel gt alloy of non-metal carbon and other
  elements dissolved in iron.

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• Particles in Solutions Are Extremely Small!!! 
• So small that they never settle out, nor can
  they be filtered out of these mixtures.
• So small they cannot scatter light.

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Concentration of Solutions

• a measure of the amount of solute dissolved in a
  Solvent
• Expressed in (g/ml)
• Solutions can be described as concentrated or
  diluted

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• What is the concentration of a solution that has
  35g of salt dissolved in 175 mL of water?
• What is the concentration of Solution A if it has
  55g of sugar dissolved in 500 mL of water?
• What is the concentration of Solution B if it has
  36g of sugar dissolved in 144 mL of water?

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Solubility

• Solubility ? the ability of one substance to
  dissolve in another at a given temperature and
  pressure

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• What Affects How Quickly Solids Dissolve in
  Liquids?
• Mixing
• Heating
• Crushing
• Unlike the solubility of most solids in
  liquids, the solubility of gases in liquids
  decreases as the temperature is raised.

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Suspensions

• A mixture in which particles of a material are
  more or less evenly dispersed throughout a liquid
  or gas
• Particles are insoluble-do not dissolve in liquid
  or gas
• Often describe as heterogeneous mixtures because
  the components can be seen

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• Particles are fairly large
• Scatter and/or block light
• Makes suspension difficult to see through
• Particles are too heavy to remain mixed without
  being stirred or shaken
• Left alone, particles will settle out

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• Can be separated by a filter
• The liquid or gas will filter through but the
  particles cannot
• Other Examples of Suspensions
• Blood
• Muddy Water
• Lysol

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Colloids

• Mixture in which the particles are dispersed
  throughout but are not heavy enough to settle out
• Have properties of both solutions and suspensions

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Examples of Colloids

• Jello, Deodorant, Milk, Mayonnaise, Whipped
  Cream, Clouds, Marshmellows, Shaving Cream, Your
  Cells (particles suspended in water)

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• Products do not settle out.
• Particles are smaller than those in a suspension.
• They still scatter light.
• Cannot be separated by filtration-particles pass
  through