Untitled Lesson

SCIENCE 8
LESSON 3.05

RECORDING DISCLAIMER: THIS SESSION WILL BE RECORDED

AND DISTRIBUTED FOR LEARNING PURPOSES. LEARNING

PURPOSES INCLUDE: A LESSON REVIEW FOR STUDENTS

WHO ARE ABSENT, STUDENTS WHO WANT TO REVIEW

FOR A TEST, TEACHER GROWTH AND IMPROVEMENT, ETC.

WELCOME TO
CLASS!
TODAY'S AGENDA

• Daily Check-in

• Review of Lesson 3.05

• Practice & Exit Ticket

• To Do List

UNIT 3 STANDARDS:

MS-PS1-1. Develop models to describe the atomic composition of simple molecules

and extended structures.

MS-PS1-2. Analyze and interpret data on the properties of substances before and

after the substances interact to determine if a chemical reaction has occurred.

MS-PS1-3. Gather and make sense of information to describe that synthetic materials

come from natural resources and impact society

MS-PS1-4. Develop a model that predicts and describes changes in particle motion,

temperature, and state of a pure substance when thermal energy is added or

removed.

MS-PS1-5. Develop and use a model to describe how the total number of atoms does

not change in a chemical reaction and thus mass is conserved

UNIT 3.05 OBJECTIVES

3.05

• Explain conservation of mass in chemical reactions.

• Describe a chemical reaction using a chemical equation.

VOCABULARY

• Coefficient:

■ in a chemical equation, the numeral in front of a molecule´s

symbol, which indicates the number of molecules of a substance

involved in the reaction

● Chemical equations must be balanced to

show that no atoms are gained or lost.

3.05
INTRODUCTION

CHEMICAL EQUATIONS

WRITING EQUATIONS:

Equations must have the same number of each atom on the

reactant side as the product side.

For Example:

AlCl3 + K Al + KCl

There are 3 Cl atoms as reactants, but only one as a product.

This equation is NOT balanced!

LAW OF CONSERVATION OF MASS

Scientist, Antoine Lavoisier, was the first to explore this

concept. He discovered that the mass of reactants was always

the same as the mass of the products.

He concluded that mass could not be created or destroyed!

AlCl3 + K Al + KCl

AlCl3 + 3K Al + 3KCl

LAW OF CONSERVATION OF MASS

Scientist, Antoine Lavoisier, was the first to explore this

concept. He discovered that the mass of reactants was always

the same as the mass of the products.

He concluded that mass could not be created or destroyed!

AlCl3 + K Al + KCl

PARTS OF A CHEMICAL EQUATION:

+ SHOWS THAT THE REACTANTS ARE

GETTING ADDED TOGETHER

SHOWS THE REACTANTS

BECOMING PRODUCTS

LARGE NUMBERS SHOW

COEFFICIENTS (THE ENTIRE

MOLECULE TIMES THAT NUMBER)

SMALL NUMBERS ARE SUBSCRIPTS,
SHOWING HOW MANY OF THAT ATOM

ARE IN EACH MOLECULEI am subscript.

I DO

Chemical equation for water (H2O):

● Hydrogen needs 2 valence electrons and is usually

found in nature as H2

● Oxygen needs 8 valence electrons and is usually

found in nature as O2

I DO

Chemical equation for water (H2O):

● Hydrogen needs 2 valence electrons and is usually

found in nature as H2

● Oxygen needs 8 valence electrons and is usually

found in nature as O2

WE DO

Balance this equation:

CH4 + O2 CO2 + H2O

WE DO

Balance this equation:

Na + Cl2 NaCl

WE DO

Balance this equation:

Fe + O2 Fe2O3

YOU DO:

Balance the equation:

N2 + O2 NO2

ACTIVITY

TIME!

• COMPLETE LESSON 3.05!

• CHECK YOUR GRADES FOR

MISSING AND MAKE-UP WORK

• VISIT ME IN OFFICE HOURS FOR

EXTRA HELP!

TO DO LIST

BYE!

CONTACT ME:

[e-mail]
714-584-0015

Office Hours:

• M/T 1:45-2:30pm

• T 3:00-3:30pm

• Th/F 1:45-2:15pm