Reactants and products Get Ready for Bell Work! 2-6-18

1. Two of the following choices describe physical changes, and one of them describes a chemical change.  Select the choice that describes a chemical change.  a. A man strikes a window with a hammer shattering the glass. b. A girl crushes an empty soft drink can in her hand.  c. Rocket fuel is burned making the Space Shuttle blast off into space.

2. Students heated a white solid 2.  Students heated a white solid. The solid produced a flame during the heating process. The product cooled into a black solid.  Which statement best classifies this change? a. The change was chemical because a flame was produced. b. The change was physical because the heat produced a color change. c. The change was chemical because the substance remained in its original state.

3.  Which of these represents a chemical change? a. A small piece of ice melts, changing from a solid to a liquid. b. A ball of clay sinks in water, and floats when reshaped. c. A match is lit, creating a yellow-orange flame.

4. A physical change is any change NOT involving a change in the substance's chemical identity. Which statement best describes a physical change? a. A process separates water into hydrogen and oxygen. b. Salt added to a cup of water makes salt water. c. An iron nail exposed to the atmosphere forms rust.

5. When elements form mixtures, the elements keep their original properties. react to form a new substance with new properties. combine in a specific mass ratio. always change their physical state.

6. Look at the model. How many valence electrons are in the Nitrogen atom? 7 2 3 5

7. What is the maximum number of electrons that can be in an atom’s 2nd energy shell? 18 24 8

Reactant and Product Video

1. Two of the following choices describe physical changes, and one of them describes a chemical change.  Select the choice that describes a chemical change.  a. A man strikes a window with a hammer shattering the glass. b. A girl crushes an empty soft drink can in her hand.  c. Rocket fuel is burned making the Space Shuttle blast off into space.

2. Students heated a white solid 2.  Students heated a white solid. The solid produced a flame during the heating process. The product cooled into a black solid.  Which statement best classifies this change? a. The change was chemical because a flame was produced. b. The change was physical because the heat produced a color change. c. The change was chemical because the substance remained in its original state.

3.  Which of these represents a chemical change? a. A small piece of ice melts, changing from a solid to a liquid. b. A ball of clay sinks in water, and floats when reshaped. c. A match is lit, creating a yellow-orange flame.

4. A physical change is any change NOT involving a change in the substance's chemical identity. Which statement best describes a physical change? a. A process separates water into hydrogen and oxygen. b. Salt added to a cup of water makes salt water. c. An iron nail exposed to the atmosphere forms rust.

5. When elements form mixtures, the elements keep their original properties. react to form a new substance with new properties. combine in a specific mass ratio. always change their physical state.

6. Look at the model. How many valence electrons are in the Nitrogen atom? 7 2 3 5

7. What is the maximum number of electrons that can be in an atom’s 2nd energy shell? 18 24 8

I Can… Identify products Identify reactants Show proof of the law of conservation of mass TOC #14 Reactants and Products notes #15 Rules for counting atoms

What is a Chemical reaction? ⏏ What is a Chemical reaction? A CHEMICAL REACTION IS THE PROCESS OF A SUBSTANCE COMPLETELY CHANGING TO A DIFFERENT SUBSTANCE WITH DIFFERENT PROPERTIES WHY ARE THERE CHEMICAL REACTIONS? CHEMICAL REACTIONS HAPPEN WHEN MOLECULES BUMP INTO EACH OTHER CAUSING THE STARTING BONDS TO BREAK APART, THE ATOMS REARRANGE, AND NEW BONDS ARE FORMED

Example: CH4 + O2 → CO2 + H2O Example: CH4 + O2 → CO2 + H2O SAME CARBON Methane fire Yield sign means EQUAL to

7 Clues of a chemical reaction: CHANGE IN COLOR FORMATION OF GAS SOLID FORMED CALLED PRECIPITATE LIGHT IS EMITTED CHANGE IN TEMPERATURE CHANGE IN SMELL OR TASTE IRREVERSIBLE

CHEMICAL SYMBOL - SHORTER WAY TO WRITE AN ELEMENTS NAME CHEMICAL SYMBOL - SHORTER WAY TO WRITE AN ELEMENTS NAME. CHEMICAL FORMULA -SHORTHAND WAY TO USE CHEMICAL SYMBOLS AND NUMBERS TO REPERESNT A SUBSTANCE.

A CHEMICAL FORMULA SHOWS THE NUMBER OF ATOMS OF EACH ELEMENT IN A MOLECULE EXAMPLES: H2O SO4 Ca(OH)2

Chemical formulas use subscripts and coefficients to show the number of atoms and molecules. SUBSCRIPTS THE SMALL NUMBER TO THE RIGHT OF THE ELEMENT THAT TELLS THE NUMBER OF ATOMS Examples: H2O SO4 Ca(OH)2

COEFFICIENTS - LARGE NUMBER TO THE LEFT OF THE ELEMENT COEFFICIENTS - LARGE NUMBER TO THE LEFT OF THE ELEMENT. APPLIES TO THE WHOLE MOLECULE! *Look at the molecule below. How many Hydrogen atoms are in the molecule? How many Oxygen atoms? 2H2O H = ____ O=_____

Different house Partner How many atoms? 3Ca(OH)2 Ca = ____ O = ____ H = ____ 4SO4 S = ____ O = ____

LAW OF CONSERVATION OF MASS LAW OF CONSERVATION OF MASS STATES THAT MASS CAN NOT BE CREATED OR DESTROYED CHEMICAL EQUATION CHEMICAL EQUATION IS AN EASIER AND SHORTER WAY TO WRITE A CHEMICAL REACTION USING CHEMICAL SYMBOLS AND FORMULAS AS A SHORTCUT TO DESCRIBE A CHEMICAL REACTION

Example: CH4 + O2 → CO2 + H2O Reactants: what you start with Products: what you end with An equation is balanced when the number of atoms in the reactants are = to the number of atoms in the products

H2O You balance an equation by changing the coefficients, not the subscript! 2H2O 4H2O

Same group partner TRUE OR FALSE Coefficients are used as multipliers against the Subscripts to balance chemical equations.