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​Learning Target:

• ​ I know

  • ​How to define chemical reactions

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​Success Criteria:

• ​ I can

  • ​write a chemical formula when given reactants and products

​Reaction...

​What does this word make you think of????

​What are everyday reactions

​English definition:

​- a response or change in a person as a result of a situation or stimulus

​

​Reactions include:

​1. emotional responses

​2. verbal responses

​3. behavioral responses

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​Reactions are a change in our behavior based on the action of something else.

​Examples

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​How does this relate to physical science...

​A CHEMICAL reaction is a result or change in which one or more substances are converted into one or more different substances.

​- Chemical reactions take place all around us everyday

​Examples:

-​Baking a cake

- metals rusting

​-digesting food

​Parts of a chemical reaction

​A + B

​Reactants

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-​Reactants are starting material that will react

​- written on left side of the arrow

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​C + D

​Products

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​-Products are the new substances produced in the reaction.

​- Written on the right side of the arrow

​How do we know when a reaction has taken place?????

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​Any ideas??????

​We look for indicators (evidence of change)

​There are a few indicators of a chemical rxn:

​changes in ​color

• ​changes in temperature

  • gets hot or cold

• ​ production of gas

  • ​ex: bubbles

• ​formation of a precipitate

• ​production of light or sound

  • ​energy

​Production of Gas

​The formation of gas is a result of combining substances

• ​Examples:

  • ​bubbling

  • ​fizzing

  • ​foaming

​Formation of a precipitate

​Precipitates are solids that are produced as a result of a reaction in solution. It separates from the solution.

​Color Change

​Color change is an indication of substances that have been mixed and have produced a different color from the original substances.

​Change in temp.

​After the substances are mixed, the surrounding area becomes cooler or hotter than the original temperature.

​Production of light or sound

​This is when energy gets released by matter. You may see a flash of light or hear a sound such as a "pop" or "bark"

​Antoine Lavoisier

​French chemist who studied chemical rxns using scientific methods.

• ​Developed the law of conservation of mass

​Law of conservation of mass

​Law that states...

• ​In a chemical reaction (rxn), matter is not created nor destroyed, but is converted (transformed)

  • ​that the total mass of the products must always equal the total mass of the reactants

In other words....

​the amount you start with is the amount you end with

​What does this mean?

​Atoms cannot be created or destroyed in a reaction, they can only be rearranged

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This can be useful for determining the amount (mass) of a missing reactant or product​​