BELL WORK 4/20/15 ANSWER ALL 3 OF THE FOLLOWING QUESTIONS: IS NaCl AN ELEMENT OR COMPOUND? EXPLAIN WHAT SKILL YOU NEED TO KNOW TO SOLVE THIS? DOES A CHEMICAL REACTION OCCUR TO FORM NaCl?

STUDENT LEARNING OBJECTIVES SPI IDENTIFY THE COMMON OUTCOME OF ALL CHEMICAL CHANGES SPI CLASSIFY COMMON SUBSATNCES AS ELEMNTS OR COMPOUNDS BASED ON THEIR SYMBOLS OR FORMULAS SPI INTERPRET THE RESULTS OF AN INVESTIGATION TO DETERMINE WHETHER A PHYSICAL OR CHEMICAL CHANGES HAS OCCURRED. SPI IDENTIFY THE REACTANTS AND PRODUCTS OF A CHEMICAL REACTION SPI RECOGNIZE THAT IN A CHEMICAL REACTION THE MASS OF THE REACTANTS IS EQUAL TO THE MASS OF THE PRODUCTS (LAW OF CONSERVATION OF MASS) TOC: #93 CH 13- CHEMICAL REACTIONS NOTES

A CHEMICAL FORMULA SHOWS THE NUMBER OF ATOMS OF EACH ELEMENT IN A MOLECULE EXAMPLES: H 2 O SO 4 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: H 2 O SO 4 Ca(OH) 2

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

ANSWER QUESTIONS IN NOTES 3Ca(OH) 2 CA = ____ O = ____ H = ____ 4SO 4 S = ____ O = ____

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 LAW OF CONSERVATION OF MASS LAW OF CONSERVATION OF MASS STATES THAT MASS CAN NOT BE CREATED OR DESTROYED

EXAMPLE: CH 4 + O 2 → CO 2 + H 2 O 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

__H 2 + __O 2 → __H 2 O ELEMENT BEFOREAFTER H = ____ _____ O = ____ _____ Example #1

__Mg + __O 2 → __MgO Element BeforeAfter Mg = ____ _____ O = ____ _____ Example #2