Get out your notebook and turn to the warm up page

1

• Get out your notebook and turn to the warm up
  page
• Write down any observations you can make about
  the two different substances in the jars on my
  desk

2

• After the demonstration, write down any new
  observations including what happened to each
  substance

3
Compounds, Mixtures and Solutions
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Compounds Vs Elements
Compounds Elements
Pure substances made up of two or more elements The elements are chemically combined A single particle of a compound is called a molecule Molecules are made up of atoms of elements Pure substance that can not be broken down into simpler substances A single particle of an element is called an atom
5
Compounds Vs Elements
Common Compounds Common Elements
Table salt -sodium and chlorine Water -hydrogen and oxygen Vinegar -hydrogen, carbon and oxygen Baking soda -sodium, hydrogen, carbon and oxygen gold Silver Aluminum Carbon Oxygen hydrogen
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Properties of compounds

• Every compound has a unique set of properties
• These properties are similar to those of elements
• Ex melting or boiling points, density, color,
  etc
• A compounds properties are sometimes very
  different from the properties of its individual
  elements
• Ex
• sodium (an alkali metal) is a highly reactive
  solid
• Chlorine is a poisonous gas
• When they combine, they form table salt which is
  safe to eat

7
Break it down

• Some compounds can be broken down into their
  individual elements
• Ex water can be broken down into hydrogen and
  oxygen by using extremely high amounts of energy
• Other compounds are broken down into simpler
  compounds which can then be split into their
  elements
• Ex carbonic acid creates the bubbles in your
  soda
• Carbonic acid breaks down into carbon dioxide and
  water once the soda is opened
• The carbon dioxide and water then break down into
  carbon, oxygen and hydrogen
• Breaking down compounds can only be done through
  chemical changes and typically require the
  addition of heat or energy

8
Mix it up

• A mixture is a combination of two or more
  substances that are not chemically combined
• All of the substances keep their individual
  properties
• Ex a salad you mix all of the vegetables
  together in a bowl, but you still have individual
  carrots, lettuce, tomatoes, etc

9
Whered it go?

• You wont always be able to see the substances
  that make up a mixture
• Ex salt or sugar water
• salt and sugar both dissolve in water
• They retain (keep) their individual properties as
  does the water
• You can separate the salt or sugar by physical
  means
• Add heat to evaporate the water and you are left
  with the salt or sugar

10
Separation Anxiety

• How do separate the substances in a compoud?
• Through chemical changes
• How do you separate the substances in a mixture?
• Usually can be done through physical changes
• Ex
• magnetism to separate out metals
• Evaporation
• Distillation (using boiling points)

11

• Go back to your journal
• Explain which substance created a compound and
  which created a mixture when vinegar was added
• How do you know?

12
Warm up 10/5 write the questions!!

• Describe the difference between elements and
  compounds
• What is one particle of an element called?
• What is one particle of a compound called?
• What is the only way to break apart a compound?

13
Bond, Chemical Bond

• A chemical bond occurs when two or more atoms
  join to make a new substance
• To understand chemical bonding, you need to
  recall valence electrons
• We have discussed
• You can determine the of electrons in an atom
  based on its atomic number
• electrons in the outermost orbital (electron
  shell) are called valence electrons
• Valence electrons are typically the only
  electrons to be involved in bonding
• You can determine the number of valence electrons
  based on the group number of the atom

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To bond or not to bond

• Not all atoms create chemical bonds
• The noble gases of group 18 already have a full
  outer orbital with 8 electrons so they are
  happy
• Therefore, they rarely bond with other atoms
• Atoms bond by gaining, losing or sharing
  electrons
• Remember
• group 1 will usually bond with group 17 why?
• Group one wants to give away its one valence
  electron while group 17 wants to gain one more
  electron
• group 2 will usually bond with 16

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Action/Reaction

• A chemical reaction is when one or more
  substances change to make one or more new
  substances
• Ex baking a cake, burning wood
• Signs of a chemical reaction taking place
• Gas formation (bubbles)
• Solid forming (called a precipitate)
• Heat or light given off
• Color change
• What does it mean if a chemical reaction has
  occurred?
• The bonds between atoms have been broken, the
  atoms rearranged and new bonds have been created

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Reading in Chemistry

• Chemical formulas are shorthand ways to represent
  substances
• They use the chemical symbols from the periodic
  table and numbers to represent the elements and
  compounds
• Ex 1 H2O is the chemical formula for water
• The small 2 is called a subscript
• It shows that there are two atoms of hydrogen
• Because there is no subscript next to the O,
  there is only one atom of oxygen
• Ex 2 C6H12O6 Glucose
• Glucose has 6 atoms of carbon, 12 atoms of
  hydrogen and 6 atoms of oxygen

17

• Practice reading and writing chemical formulas as
  a class

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Warm up 10/6 write these questions on the next
page of your notebook not in your warm up section
and leave 1-2 lines between each

• What does the law of conservation of mass tell
  you about a chemical reaction?
• What is the mass of the experiment in the bag
  before you mix everything together?
• How do you know a chemical reaction took place in
  the bag?
• What is the mass of the experiment in the bag
  after you mix everything together?
• How does this lab demonstrate the law of
  conservation of mass?

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Doing the Math

• Chemical equations use chemical formulas and
  chemical symbols to describe chemical reactions
• The reason for using chemical equations
• They are shorter than writing out the reaction
• Anyone who can read chemical symbols can
  understand chemical equations
• Equations refer to the entire chemical reaction
  while formulas refer to a specific chemical
  compound or element

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2 parts to an equation

• There are two sides to a chemical equation,
  separated by an arrow
• The left of the arrow contains the reactants
• These are the substances that you begin a
  reaction with
• The right of the arrow contains the products
• These are the substances that you end up with
  after a reaction
• Ex C O2 ? CO2
• C O2 and are the reactants
• CO2 is the product

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Balancing act

• Atoms are never lost nor gained in a reaction,
  they are just rearranged
• The number of atoms in the products have to equal
  the number of atoms in the reactant
• A french chemist found that the total mass of the
  reactants was always the same as the total mass
  of the products
• This is called the Law of Conservation of Mass

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Experiment in a bag mini - lab

• 1. place the zip loc bag on the balance
• 2. pour the baking soda into the bag
• 3. CAREFULLY PLACE the cup of vinegar in the bag
  DO NOT SPILL THE VINEGAR!!!!
• 4. seal the bag tightly
• 5. find the mass of the bag and its contents
• 6. without opening the bag, tip over the vinegar
  cup
• 7. find the mass of the bag and its contents now
• 8. answer the questions from your warm up

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Warm up 10/7 be sure to write the questions!!!!

1. What is a chemical formula?
2. What is the little number next to an element
   symbol in a formula called?
3. What does the little number mean?
4. What is a chemical equation?
5. What is the difference between the two?
6. What does the law of conservation of mass tell us?

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Balancing Act

• Balancing equations lets you show that there has
  not been any mass gained or lost
• When you balance an equation, you show that there
  are the same number of all atoms before and after
  a reaction
• Some compounds will have a number in front of the
  chemical formula
• Ex 2H2O
• The 2 in front is called a coefficient
• It symbolizes that there are two molecules of
  water
• This means that there are a total of 4 hydrogen
  atoms and 2 oxygen atoms
• When you balance an equation, you can change the
  coefficient of any of the reactants or products

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Balance this equation

• H2 O2 ?H2O
• Step 1 Count the number of atoms of each
  element
• H2 O2 ?H2O
• 2H 2O 2H 1O
• Step 2 start by balancing the oxygen atoms
  place a coefficient of 2 in front of the water
  formula
• H2 O2 ?2H2O
• 2H 2O 4H 2O
• Step 3 balance the hydrogen atoms place a
  coefficient of 2 in front of the hydrogen formula
• 2H2 O2 ?2H2O
• 4H 2O 4H 2O

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• Journal 12
• Which of these substances are mixtures? Why do
  you think so?

Sand Salt Water Steel Air
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The answer is the Solution

• Weve talked about mixtures before
• A mixture is created when two or more substances
  are physically combined
• A solution is a type of mixture that appears to
  be one single substance
• It is particles of two or more substances that
  are distributed evenly among each other
• Solutions are created because of the process of
  dissolving
• Ex salt water, sugar water

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Which is dissolved into which?

• The solute is the substance that is dissolved
• Salt is the solute in salt water
• The solvent is the substance that the solute is
  dissolved in
• Water is the solvent in salt water
• The ability to dissolve is called solubility
• If a substance can not dissolve in a solvent, it
  is said to be (called) insoluble

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Is it always a liquid?

• Examples of solutions
• Tap water
• Soft drinks
• Gasoline
• Solutions arent always liquids
• Air, a gas, is a solution
• Multiple gases are evenly spread out among each
  other
• Alloys, metals melted within each other, are
  solids and solutions

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It takes Concentration

• Concentration is the measure of the amount of
  solute dissolved in a solvent
• Solutions can either be dilute or concentrated
• If there is less solute in a solution, it is
  dilute
• If there is more solute in a solution, it is
  concentrated

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Journal 13

• What is the difference between a general mixture
  and a solution?
• What is concentration (in terms of solutions)?
• What does it mean if a solution is diluted?

32
The Suspension is killing me!

• A suspension is a mixture in which particles that
  are mixed with a liquid are large enough that
  they are able to settle
• IE Snowglobes
• If you leave a snow globe sitting on a desk, the
  snow particles will fall to the bottom
• They are too large, and too heavy, to stay
• suspended in the liquid

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Properties of a suspension

• Suspensions scatter or block light
• If you were to shine a flashlight through a
  suspension, you would not get a solid beam out
  the other side
• Suspensions can be separated by passing the
  mixture through a filter
• The filter will catch the large particles and
  allow the water to drain out

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What do you get when you cross a solution and a
suspension?

• A colloid!
• A mixture where the particles are dispersed
  throughout, but are not heavy enough to settle
• Ex the dust you see in a ray of light
• Ex fruit particles in a jello mold
• Properties
• Particles can scatter light
• Particles can not be separated
• by filtration because they are too
• small and light