MS-PS 1-5 Notes Chemical Reactions

Chemical Reactions Notes

Open Ended

What is something that may give evidence that a CHEMICAL change has occurred?

​Chemical Reactions

The substances that you begin a reaction with are your REACTANTS
The products that are formed during your reaction are your PRODUCTS

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Reactant

​Chemical Reactions

During reactions atoms are rearranged into different substances
Any atoms included in the reactants must also be shown as products

​Chemical Reactions

Law of conservation of mass- states that matter cannot be created or destroyed, only transferred
Justifies that atoms are simply rearranged in chemical reactions

Open Ended

What happens to atoms during a chemical reaction?

​Chemical Reactions

Because of the law of conservation of mass, chemical reactions must be balanced.
Balanced means that the number of atoms in the reactants is the same as in the products.
Chemical reactions occur in specific proportions
Think about baking the proportions of ingredients matter, this is because it is an example of a chemical reaction!

Open Ended

What is wrong with the chemical reaction you see in the picture?

​Chemical Reactions

Bonds hold atoms together in compounds
During reactions bonds are broken and new bonds are formed

​Chemical Reactions

Breaking bonds and forming new bonds require energy
Energy must be added or used to break bonds
Energy is released or given off when bonds are formed

Multiple Choice

Breaking bonds

• Requires Energy (Is added)

• Releases Energy (Is given off)

​Chemical Reactions

Energy, like mass, can never be created nor destroyed
It can be transferred from one substance to another or given off into it's environment

​Chemical Reactions

Parts of a Chemical Equation
Symbol- Tells which elements are being used in the reaction
Subscript- Tells how many atoms of each element is in a compound
Subscript goes with the element IN FRONT of it
Coefficient- Tells how many atoms/molecules of a compound one has

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Identify the COEFFICIENTS

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Identify the subscripts

Multiple Choice

How many Nitrogen Atoms are in the reactant side?

• 0
• 3
• 2
• 1

Multiple Choice

How many Hydrogen Atoms are in the reactant side?

• 3

• 6

• 2
• 1