CHEMISTRYScience 9

WHY STUDY CHEMISTRY?

• In this unit we will be studying atoms, elements and compounds

• Brainstorm with a partner how you would complete the following sentenceso We are studying chemistry and atoms, elements

and compounds because…….

o Studying chemistry is of importance in my life because…….

o Some things in my everyday life that has to do with chemistry are……

LESSON 1: SAFETY

Science 9

SAFETY IN THE SCIENCE

CLASSROOM• You will be assigned 1 safety rule on pages 10-11• Use the poster paper provided and felts/pencil

crayons to make a poster with your safety rule• We will be putting these up in the classroom so

take time to make it presentable• You will each present your safety rule to the class

• We will have a short quiz at the end of the activity where you will gallery walk around the room to find the answers to the quiz

WHMIS SYMBOLS• WHMIS: Workplace

Hazardous Materials Information Systemo Symbols are used for

chemicals o Tells us about the hazards of

the chemicalo There are 8 symbols

o YES…you need to know these!

LESSON 2: INVESTIGATIN

G MATTERScience 9

What is matter?• Matter: anything that has mass or volume

o Mass: amount of matter in a substance or object (grams)o Volume: amount of space of a substance or object occupies (litres)

• Matter can change in 2 ways:o Chemical changeo Physical change

Chemical Change• Chemical Change: change in matter when

substances combine to form new substanceso Example: when you light a sparkler it glows white because it contains

magnesium and it glows whiteo Example: Hydrogen and Oxygen combine to form water (H20)o Example: Sodium and Chloride combine to form salt (NaCl)

o in each of these examples, a new substance is formed

Physical Change• Physical Change: matter undergoes a change in

appearance BUT no new substances are formed• Matter undergoes a change of state• 3 states of matter

1. Solid- matter has a defined shape and volume• Example- ice

2. Liquid- has volume but shape is determined by its surroundings• Example- water

3. Gas- mass and volume are determined by its surroundings• Example- evaporated water (steam)

Kinetic Molecular Theory (KMT)

• Kinetic Energy: energy of motion• All particles (solid, liquid and gas) are always in

motion• KMT: the theory that explains what happens to

particles when they change between states

KMT: The Main Points• There are 4 main parts to the KMT theory

1. All matter is made up of small particles2. There is empty space between all particles3. Particles are constantly moving regardless of state

1. Solid- particles packed so close together that they only vibrate2. Liquid- particles farther apart so they move more and slide against

one another3. Gas- particles are very far apart, they move quickly

4. Energy makes particles move• More energy…particles move faster

KMT Demo• Volunteers Please!

Temperature and Changes of State

Temperature and Changes of State

• Melting: solid liquid at a certain melting point• Evaporation: liquid gas• Deposition: gas solid

• Sublimation: solid gas• Condensation: gas liquid• Solidification: liquid solid

How do we describe matter?

• To describe matter we observe the physical properties of a substance in 2 ways1. Qualitative properties: properties can be described but not measured2. Quantitative properties: characteristics that can be measured

How do we describe matter?

• Qualitative Properties o State- solid, liquid or gaso Color- what color is the substance?o Malleability- ability to be beaten into sheetso Ductility- ability to be drawn into wireso Crystallinity- shape or appearance of crystalso Magnetism- tendency to be attracted to a magnet

How do we describe matter?

• Quantitative Propertieso Solubility- ability to dissolve in watero Conductivity- ability to conduct electricity or heato Viscosity- resistance to flowo Density- ratio of a material’s mass to its volumeo Melting/Freezing point- temperature of melting/freezing pointo Boiling/Condensing Point- temperature of boiling/condensing point

Pure Substance• Pure Substance: a substance

made up of only one kind of matter (gold, water, oxygen)

• 2 kinds of pure substances1. Element- a pure substance that cannot be

broken down or separated into smaller substances • Example: gold, oxygen

2. Compound- a pure substance composed of at least 2 elements• Example: water

Assignment• Page 27 #1-16

LESSON 3: ATOMIC THEORY

Science 9

Think-Pair-Share• Turn to a partner and discuss what you already

know about atoms and the atomic theory• We will share out as a class to see what we

already know about the atom

Development of the Atomic Theory

• The current view of the atomic theory tells us how an atom is constructed

• There were 4 scientists that helped develop the current accepted atomic theory: Dalton, Thomson, Rutherford, Bohr

• On a piece of paper and using pages 29-31 make notes of what these 4 scientists contributed to the atomic theory

• You will have 15 min to do this then we will continue with the lesson

JOHN DALTON(1766-1844)

• Dalton’s Atomic Theoryo All matter is made of small particles

that we call atomso Atoms cannot be created, destroyed

or divided into smaller particleso All atoms of the same element are

identical in mass and sizeo Atoms of different elements are

different in mass and sizeo A compound is when atoms of

different elements join together in definite proportions (ex- water)

JJ THOMSON(1856-1940)

• British physicist studied electric current in gas discharge tubes

• 1897- discovered the electron as streams of negatively charged particles

• ‘raisin bun’ model of the atom: a positively charged ball like a bun with negatively charged electrons embedded in it like raisins

• This model was quickly changed with Rutherford’s research

ERNEST RUTHERFORD

(1871-1937)• 1909: Designed an experiment to probe inside the atom

o Exposed a thin sheet of gold to a stream of heavy positive particles (alpha particles)

o Used a fluorescent detector screen which lights up when struck by an alpha particle

o Most particles went through the gold as expectedo A few bounced backwards…he discovered the nucleus!

• Discovered the nucleus, the proton and the neutrono A decade after his original experiment he concluded that the nucleus was made

of 2 particles, a positive proton and a neutron with no electric charge

NEILS BOHR(1885-1962)

• Worked under Rutherford• He proposed that electrons surround the nucleus in energy

levels or ‘shells’• When electricity is added to neon gas the electrons gain

energy and jump from low to high energy levels, when they drop energy/levels the release visible light this proved that electrons exist in energy levels

ATOMIC THEORY• So now we have a clear idea of what’s in an atom

and how it was discovered

• Atom: smallest particle of an element that still retains the properties of the element

• The atom if composed of 3 subatomic particles:o Protono Neutrono Electron

MASS• Protons and neutrons have more mass than

electrons• Electron mass is negligible compared to protons

and neutrons

ELECTRIC CHARGE• There are 2 types of electric charges: positive and

negative• Protons positive• Electrons negative• Therefore, protons and electrons are attracted to

one another• Charges add up to zero making the atom

uncharged or neutral

ATOMIC THEORY• Subatomic particles differ in mass and electric

charge

Name Symbol

Relative Mass

Electric Charge

Location in the atom

Proton p 1836 + Nucleus

Neutron n 1837 0 Nucleus

Electron e 1 - Surrounding nucleus

NUCLEUS• Tiny region at the centre of the atom• Positively charged because of protons• Contains neutrons with no charge• Protons and neutrons never leave the nucleus

ELECTRON• Occupy shells that surround the nucleus• Negligible mass• Account for 99.99% of the volume• Not a fast moving particle, rather it exists like a

spread out negative charge around the nucleus

ASSIGNMENT• Page 37 #1-15

LESSON 4: THE

ELEMENTSScience 9

A TOUR OF THE COMMON

ELEMENTS• Recall elements have physical properties (ex-

state and color) as well as chemical properties (ex-its ability to react)

• The periodic table has 2 main types of elements, metals and non metalso Metals: typically hard, shiny, malleable, ductile and good conductors of

heat and electricityo Non-Metals: tend to not share the properties of metals and are usually

gases or brittle solids at room temperatureo Metals and non metals vary in their reactivity

A TOUR OF THE COMMON

ELEMENTS• Turn to page 45-47• There are 8 common elements-4 are metals and 4

are non-metals• Use the handout provided to summarize these 8

common elements in your own words

THE PERIODIC TABLE• The Periodic Table Overview

o Organizes the elements into their propertieso Listed in rows according to increasing atomic numbero Rows are arranged to elements with similar properties line up in

vertical columnso Rows called periodso Columns called families or groupso 2 families of metals

• Alkali metals• Alkaline earth metals

o 2 families of non metals• Halogens• Noble gases

DIMITRI MENDELEEV

• A Russian teacher and chemist who was the first person to organize the elements into what has becomes today’s periodic table

THE PERIODIC TABLE• Atomic Number: number of protons in the nucleus

of an element• Atomic Mass (weight): mass of the average atom

(units are atomic mass unit)• Ion charge: when an atom gains or losses

electrons and electric charge forms on the atom called the ion chargeo Some atoms have more than one ion charge

GETTING TO KNOW THE PERIODIC TABLE• Use the handout of the Blank Periodic Table of

Elements and Page 54 of your textbook• Use the information of page 54 to make your own

periodic table• Use pencil crayon to color the metals, metalloids

and non-metals• Be sure to include the element name, element

symbol, atomic number, ion charge and atomic mass we will learn what these are tomorrow

LESSON 5: THE PERIODIC

TABLEScience 9

Think-Pair-Share• Brainstorm with a partner what you know about

the Periodic Tableo What is it?o Why do we have it?o What kinds of things does it tell us?

THE PERIODIC TABLE• The Periodic Table Overview

o Organizes the elements into their propertieso Listed in rows according to increasing atomic numbero Rows are arranged to elements with similar properties line up in

vertical columnso Rows called periodso Columns called families or groupso 2 families of metals

• Alkali metals• Alkaline earth metals

o 2 families of non metals• Halogens• Noble gases

DIMITRI MENDELEEV

• A Russian teacher and chemist who was the first person to organize the elements into what has becomes today’s periodic table

THE PERIODIC TABLE• Atomic Number: number of protons in the nucleus

of an element• Atomic Mass (weight): mass of the average atom

(units are atomic mass unit)• Ion charge: when an atom gains or losses

electrons and electric charge forms on the atom called the ion chargeo Some atoms have more than one ion charge

METALS, NON METALS,

METALLOIDS• Mendeleev arranged the elements according to their

properties• He noticed that 3 main groups existed: metals, non metals,

metalloidsState at RT

Appearance

Conductivity

Malleability and Ductility

Metals Solid, except for mercury (a liquid)

Shiny lustre Good conductors

MalleableDuctile

Non Metals Some gasesSome solidsOnly Br liquid

Not very shiny

Poor conductors

BrittleNot ductile

Metalloids solids Can be shiny or dull

May conduct or may not

BrittleNot ductile

PERIODS AND FAMILIES

• Periodo Horizontal row = periodo There are 7 rows on the periodic table

• Familyo Vertical row = familyo There are 18 columns on the periodic tableo Families share similar physical and chemical propertieso 4 families: alkali metals, alkaline earth metals, halogens,

noble gases

ALKALI METALS(GROUP 1 EXCLUDING

HYDROGEN)• Li, Na, Rb, Cs, Fr• Highly reactive• React with water and oxygen• Reactivity increases as you go down the table• Low melting points• Soft, can be cut with a knife

ALKALINE EARTH METALS(GROUP 2)

• Be, Mg, Ca, Sr, Ba, Ra• Less reactive than alkali metals but will burn in air

if heated• Used in fireworks

o Example: red fireworks caused by strontium• React with water but not as much as alkali metals

HALOGENS (GROUP 17)

• F, CL, Br, I, At• Non-metals• Highly reactive• Fluorine and chlorine are gases at RT• Bromine is a liquid• Iodine is a solid• Fluorine is the most reactive and iodine is the

least

NOBLE GASES(GROUP 18)

• He, Ne, Ar, Kr, Xe, Rn• Most stable and unreactive elements• At RT: colorless, odourless gases• Some glow distinctive colors such as neon• Helium is lighter than air which is why helium

balloons float

MEET THE ELEMENTS LAB

• Read the Meet the Elements Lab on Page 43• Work with a partner to get to “Meet the

Elements”• Record your findings on the handout provided

LESSON 6: THE PERIODIC TABLE

AND ATOMIC THEORY

SCIENCE 9

What do we know?• We know that the periodic table is arranged so

that elements with similar properties are lined up..but why?o Patterns occur as a result of regular changes in the structure of the

atoms of the elementso Elements with similar properties line up in columns because all those

elements are similar in the arrangement of their electrons

BOHR MODEL• Recall Neils Bohr...• He came up with the Bohr model diagram that

shows us how electrons are in arranged in electron shells (also called valence shells)

• Electron shells are arranged as follows:o First shell- 2 electronso Second shell- 8 electronso Third shell- 8 electronso Fourth shell- 18 electrons

BOHR MODEL• So how do we draw a Bohr model?

o STEP 1: Figure out how many protons and electrons there are atomic number

o STEP 2: Figure out how many neutrons there are atomic mass - atomic number

o STEP 3: Write the number of protons and neutrons in the nucleuso STEP 4: arrange the electrons into shells of 2 e, 8 e, 8 e, 18 eo Example-Calcium

YOUR TURN• You are expected to know how to draw Bohr

models for elements 1-20• Use only your periodic table and a piece of paper

to draw the Bohr diagram for elements 1-20• You will have 20 min to work on this

• This is your ticket out the door…show me your completed Bohr models

WHAT DO WE NOTICE?

• The outer valence shell contains what we call the valence electronso Example: calcium has 2 valence electrons

• Most elements in the same family have the same number of valence electronso Halogens have 7 valence electronso Noble Gases have 8 valence electrons

• Elements in the same period have valence electrons in the same shell

• The period number indicates the number of shells that have electrons

NOBLE GAS STABILITY

• Noble gases are unreactive and very stable, but why?

• Look at the noble gases Bohr models (Helium, Neon and Argon)…what do you notice about these 3 Bohr models?

NOBLE GAS STABILITY

• The noble gases all have full outer valence shells which makes them very stable

• For a compound to be made atoms have to gain, lose or share electrons in order to make a new substance

• Atoms with full valence shells do not easily trade or share electrons

• This leads to noble gas stability!

WHAT’S SO GREAT ABOUT STABILITY???• So we know the noble gases are stable, and we

know why• Most other atoms try to make themselves stable

by gaining or losing electronso Metals lose their valence electrons to become stable like the noble

gaseso Non-Metals gain electrons to become stable like the noble gases

• The result an ion

HOW ATOMS BECOME IONS

• Ion: an atom that has gained or lost electrons and therefore carries a chargeo An atom of any metal loses electrons becomes a positive ion (+)o An atom of any non-metal except a noble gas gains electrons

becomes a negative ion (-)o The charge on an ion is equal to the sum of the charges of protons and

electrons• Example: Mg +2- has 12 protons and 10 electrons

IONSLithium Magnesium Chlorine

Atom Li 3p 2, 1 Mg 12p 2, 8, 2

Cl 17p 2, 8, 7

Ion Li+ 3p 2 Mg+2 12p 2, 8

Cl- 17p 2, 8, 8

Look at Lithium…what happened to give the ion a positive charge?

Look at Magnesium…what happened to give the ion a +2 charge?

Look at Chlorine…what happened to give the ion a negative charge?

ASSIGNMENT• Page 71, # 1, 3-12, 14

LESSON 7: COMPOUNDS

SCIENCE 9

WHAT IS A COMPOUND?

• A compound is a pure substance made up of 2 or more kinds of elements that chemically combine

• Elements combine using chemical bonds which link the atoms together

• 2 types of compoundso Covalent compoundso Ionic compounds

COVALENT COMPOUNDS

• Atoms combine by sharing electrons to form molecules

• These shared electrons form covalent bonds that hold the atoms together

• Examples: carbon dioxide, water

IONIC COMPOUNDS• Atoms gain or lose electrons to form ions• Example: sodium chloride (NaCl)

o Atoms start out neutral (with no charge) but as they move towards one another an electron is transferred

o Sodium becomes a positive ion (Na+)…it loses an electrono Chlorine becomes a negative chloride ion (Cl-)…it gains an electron

TO RECAP

POLYATOMIC IONS• Sometimes a compound has both ionic and

covalent bonds within the same compound• When this happens you get a molecular ion called

a polyatomic ion (‘poly’ means many)• Example: potassium dichromate

o Covalent bonds between oxygen and chromiumo Ionic bonds between dichromate ion and potassium

ASSIGNMENT• Page 83 #1-7, 10-12

LESSON 8: NAMING

COMPOUNDSSCIENCE 9

REVIEW• Brainstorm with a partner…

oWhat is the main difference between an ionic and a covalent bond?

oWhat is a polyatomic ion?

#1-DRAW SOME BOHR MODELS

• Draw the Bohr model for Sodium• Draw the Bohr model for Chlorine

• Now…try to draw the Bohr model for a compound containing sodium and chlorine called… sodium chlorideo Notice the change of chlorine to chloride when written as a chemical

name

#2-DRAW SOME BOHR MODELS

• Draw the Bohr model for Potassium• Draw the Bohr model for Flourine

• Now draw the Bohr model for a compound that has potassium and bromine…Potassium Flouride

#3-DRAW SOME BOHR MODELS

• Draw a Bohr model for Calcium• Draw a Bohr model for Flourine

• Now draw a Bohr model for Calcium Flouride

• What do you notice about the Bohr model compound for Calcium Flouride?

#4-DRAW SOME BOHR MODELS

• Draw a Bohr model for Aluminum• Draw a Bohr model for Chlorine

• Now draw the Bohr model of the compound Aluminum Chloride

• What do you notice about the Bohr model?

A COMPOUND HAS A NAME AND A FORMULA• Ionic compounds have positive and

negative ions• Chemical name is how we name ionic

compounds• There are 2 parts to the chemical name of

an ionic compoundo Positive ion is named first and is always a metalo Negative ion is named second and is always a non-metal

• The suffix is always changed to “ide”• Example: flouride, chloride, bromide, iodide, oxide, nitride,

phosphide

LET’S PUT SOME OF THESE TOGETHER…• The following elements will combine

to form ionic compounds. Give the name the following ionic compounds:1. Calcium and Nitrogen2. Potassium and Oxygen3. Lithium and Chlorine4. Magnesium and Sulphur5. Silver and Flourine

PRACTICE PROBLEMS

• See page 86 and do practice problems 1a-o

A CHEMICAL FORMULA

• Chemical formula of an ionic compound has symbols that identify each ion

• It also shows the number of ions in the compound• These numbers are shown as subscript

• Look back at your Bohr models for sodium chloride and potassium flouride and see if you can write the chemical formula

• Look back at your Bohr models for calcium flouride and aluminum chloride and see if you can write the chemical formulas

A CHEMICAL FORMULA

• Sodium chloride NaClo There is 1 sodium atom for every 1 chlorine atom

• Potassium flouride KFo There is 1 potassium atom for every 1 flourine atom

• Calcium flouride CaF2 o There is 1 calcium atom for every 2 flourine atoms

• Aluminum chloride AlCl3o There are 1 aluminum atoms for every 3 chloride atoms

RULES FOR WRITING CHEMICAL FORMULAS

• When writing ionic compound formulas we need to balance the positive and negative charges

• The easiest way is to determine the ratio of atoms in the compoundo Recall calcium flouride has a calcium to every 2 flourine’s CaF2

RULES FOR WRITING CHEMICAL FORMULAS

• 4 Step Process to Write chemical formulas:1. Identify each ion and its charge

• Example: zinc: Zn2+ nitride: N3-

2. Determine the total charges that needed to balance positive and negative charges• Example: Zn2+ : +2 +2 +2 = +6• N3- : -3 -3 = -6

3. Note the ratio of positive to negative ions• Example: 3 Zn2+ ions for every 2 N3- ions

4. Use subscripts to write the formula• Example: Zn3N2

• You try… write the chemical formula for aluminum chloride

PRACTICE PROBLEMS

• Page 87 #1a-f and #2a-n

LESSON 9: CHEMICAL FORMULAS

SCIENCE 9

REVIEW• Name the following ionic chemical

formulaso CdSo AgIo CaSeo NaFo CaI2

WRITING IONIC CHEMICAL FORMULAS

• Step 1: Find the chemical symbols on the periodic table of the elements in the compound

• Step 2: Figure out the charges on each element…recall, ionic compounds consist of charged ions

• Step 3: Criss cross the charges to write the chemical formula

• Example: Zinc nitrideo Zn+2

o N-3

o Zn3N2

TRY THE FOLLOWING• Write the chemical formulas for the

following compoundso Magnesium chlorideo Zinc oxideo Aluminum phosphideo Sodium nitrideo Calcium oxide o Cesium sulphide

WHAT ABOUT IONS WITH MORE THAN ONE

CHARGE?• Look at the periodic table…which of the first 20

elements have more than one ionic charge?

• How can we distinguish which ion is involved in an ionic compound if there is more than one choice of ionic charge?

MULTIVALENT METALS

• Many metals have more than one ionic charge• They are called multivalent metals• When writing ionic compounds involving a

multivalent metal we need to distinguish which ion charge is in the compound

• We use Roman Numerals to do thiso +1 Io +2 IIo +3 IIIo +4 IVo +5 Vo +6 VIo +7 VII

MULTIVALENT METAL FORMULAS

• Step 1: Identify each ion and its charge in the formula

• Step 2: Criss cross the charges

• Step 3: Write the formula

• Example: iron (III) suphideo Iron (III): Fe +3 sulphide: S-2

o Fe2S3

YOU TRY• Practice Problems Page 89 1a-n

MULTIVALENT METAL NAMES

• Step 1: Identify the metals

• Step 2: Determine which ion charge will balance the non-metal

• Step 3: Name the compound and include the roman numeral that states the ion charge of the metal

• Example: Cu3Po Copper can be +2 or +1o The formula states that for every 1 phosphide you have 3 coppero The charge on phosphide is +3o Balance the charges!o Copper (I) phosphide

YOU TRY• Practice Problems Page 90 1a-o

LESSON 10: CHEMICAL FORMULAS

CONT’DSCIENCE 9

CHEMICAL FORMULAS TO

KNOW…1. Ionic compounds2. Ionic compounds with a multivalent metal3. Ionic compounds with a polyatomic ion

• You are expected to know how to write the names of these types of compounds AND write the chemical formulas of these types of compounds

COMPOUNDS WITH POLYATOMIC IONS

• Recall that a polyatomic ion is an ion that has both covalent and ionic bonds within it

• They carry a charge (positive or negative)• They always pair up with ions of opposite charge• We use a list of known polyatomic ions to write

chemical formulas

TABLE OF COMMON POLYATOMIC ION

WRITING FORMULAS WITH POLYATOMIC

IONS• Step 1: Identify each ion (to do this you will have

to use the table of polyatomic ions)• Step 2: Identify each charge• Step 3: Criss cross the charges

• Example: iron (III) hydroxideo Iron: Fe 3+

o Hydroxide: OH- (polyatomic ion)o Fe(OH)3

ANOTHER EXAMPLE• Ammonium carbonate

• Ammonium: NH4+

• Carbonate: CO32-

• Criss cross the charges

• (NH4)2CO3

LET’S PRACTICE• Practice problems: Page 91 #1 a-j and #2 a-j

ASSIGNMENT• PAGE 95: 1-6

• You’ll be handing this in as an assignment because I need to know that YOU know how to write and name these chemical formulas…due NEXT CLASS

LESSON 11: PHYSICAL AND

CHEMICAL CHANGES

SCIENCE 9

REVIEW• The easiest way to think about naming chemical

formulas….

• Step 1: look at the elements involved, if there is one metal and one non-metal each with only 1 charge, it is a simple ionic compound

• Step 2: if there is a metal with more than one charge it is a multivalent metal and you MUST add in a roman numeral

• Step 3: if there is a polyatomic ion you must look at the list of polyatomic ions to find its name

Let‘s go back to our first lesson…

• Recall we started this unit discussing matter

• What did we say was a physical change?

• What did we say was a chemical change?

PHYSICAL CHANGES• A change in state• No new substances are formed• No new bonds have formed or broken• Energy changes…recall KMT• Ripping, cutting, grinding and tearing are

examples of physical changes

• Example: chocolate left in the Suno Chocolate will melt because of increased energy from the Suno The atoms in the chocolate are still the same but the state has

changedo Nothing new was created…its still chocolate, just melted chocolate

CHEMICAL CHANGES• Produces new substances with new properties• Always involve energy changes• New bonds are formed and or are broken

• A chemical reaction:o REACTANTS PRODUCTSo Reactants are what you start with, they are what is going to undergo a

chemical reactiono Products are what you produce after the chemical reaction has taken

place

CHEMICAL REACTIONS

• Evidence of a chemical reaction:o Color changeo Heat, light, sound produced or consumedo Bubbles of gas formo A precipitate may form

• What are some examples you can think of?

CHEMICAL REACTIONS

• Rotten apples!o As an apple rots it gives off ethene gas (C2H4)o Ethene gas is a ‘chemical messenger’o Ethene gas tells neighboring apples to rot as wello One bad apples can spoil an entire batch of apples!!!

CHEMICAL AND PHYSICAL CHANGES AND

ENERGY• Chemical and physical changes often occur at the

same time• They also are accompanied by energy changes

o Example: an explosion is a rapid release of energy

• There are 2 main types of reactions:o Exothermic reactiono Endothermic reaction

EXO versus ENDO• Exothermic Reaction• “exo” means leaving• Overall release of energy by heat or light

• Endothermic Reaction• “endo” means entering• Involves the overall absorption of energy