02/03/15O To Do:

O Bell WorkO Hydrated Crystal

LabO BondingO Chemical ReactionsO Practice WSsO Complete foldable

for Ch. 8.2 – Types of Chemical Reactions

O Bell Work:O Copy To Do list

in Agenda.O Note Quiz –

complete the handout and return to Ms. M.

AnnouncementsO FoldableO Procedure Changes:

O No more test corrections, but retakes will be available.O Students who have a C- or below will receive after

school detention on Thursdays to provide time for improvement (assignment corrections, test retakes, complete missing work, etc.).O You, your parents, and the administration will be

notified.O No Late Work without Mac Pass!

O You have 4 for the semester, use them!O Complete them well, or you don’t get full credit.O May not use the last two weeks of the quarter.

Hydrated Crystal Lab

Chemical EquationsO Notes will go on pg. 70 of your SIN.

O Remember to set up Cornell notes!

Ionic BondsO What is the force behind

an Ionic Bond?O Attractions of positive

and negative ions.O Charged atoms what to

be neutral, so they are attracted to each other.

O These bonds are much harder to break in a chemical reaction.

Covalent BondsO What causes a covalent bond to form?

O The sharing of electrons to get to the happy number, 8 valence electrons.

O Hydrogen is the exception, as it is happy with 2 valence electrons.O Why is hydrogen happy with 2 valence

electrons?O Hint: look at his electron orbitals.

O How do we figure out how atoms will bond covalently?

Covalent BondsO How do we figure out how

atoms will bond covalently?O We draw Lewis dot diagrams.O Look at water to the left:

O Oxygen is sharing electrons so it has 8 electrons.

O Hydrogen is sharing 2 electrons.O Both are happy.

O Looking at these diagrams, what do you know about the number of electrons shared by atoms?

Covalent BondsO Lewis Dot Diagrams will tell

show where shared electrons will go – look at the diagram to the right.

O CO2 – Carbon is sharing 8 electrons and oxygen is sharing 4 electrons to go with the 4 it has to get to the happy number of 8.

O The second diagram shows that we can use bars to represent a pair of shared electrons.

Covalent BondsO Covalent bonds can have

multiple shared pairs of electrons.

O They will be referred to as follow:O Single Bond if it is like the water

molecule – one pair of electrons shared between atoms.

O Double Bond if it is two electrons pairs shared between atoms.

O Triple bond if it is three electron pairs shared between atoms.

O Etc.

Bonds and Chemical Reactions

O Why is it important to know about bonds when we discuss chemical reactions?O Tells you the amount and type of energy

you will get.O Ionic bonds are hard to break, taking more

energy.O Covalent bonds are easier to break, so

less energy is required.O You also need to know how atoms will

rearrange in your chemical equations.

Physical Indicators of Chemical Reactions

O Evolution of energy as heat & lightO Heat and/or light is given off when two

compounds are mixed.O Color changeO Production of gasO Formation of a precipitate

O Precipitate – when a solid is produced in a solution from a chemical reaction.

Chemical EquationsO A chemical reaction is

when the atoms of one or more substances are rearranged to form a new substance.

O Reactants are your starting material.

O Products are your ending material.

O What are the reactants and products in the equations to the right?

Chemical Equations Symbols

Chemical EquationsO Diatomic Compounds – Look up a definition in your

book!O Why do we need to keep this in mind?

Chemical EquationsO Word problems will state what is happening in a

chemical reactions:O 2 g of sodium is reacting with 2 mL of chlorine to form

sodium chloride.O What would the chemical equation look like?O Remember:

O Starting material goes on the left.O Ending material on the right.O Use a + sign to indicate something is mixing.O Separate with an arrow pointing in the direction the

reaction takes place.O Energy required it placed over the arrow.O You should list the state of the compound; (s), (g), or (l)

Chemical EquationsO Balancing Equations:

O Remember Conservation of Mass – the law that says mass is either created or destroyed.

O What you start with must be what you end with.

O If you have 4 hydrogen atoms, you must end with 4 hydrogen atoms.

Chemical EquationsO Balancing Equations:

O Word problem: methane gas (CH4) and oxygen are mixed to make carbon dioxide and water.

O What would the equation look like?

Chemical EquationsO Take what we know about chemical

formulas to figure out how the mass was calculated below.

Chemical EquationsO Balancing Equations:

O You have your equation:

CH4 + O2 CO2 + H2O

O Is this equation balanced?

Chemical EquationsO Balancing Equations:

O You have your equation:CH4 + O2 CO2 + H2O

O Is this equation balanced?O No, because if we compare the number

of atoms of each type on each side, they are not equal. Below is the correct equation.

Chemical Reactions To Do List

O Review Ch. 8.1 in your textbook.O Add any details you think are

needed.O Complete your left column, added

color and write a reflection:O How is this related to what we have

learned?O How is this going to help with what

we have left to learn?

Chemical Reactions Practice

O Practice balancing equations:O Both worksheets will be taped to pg.

69 of SIN.

O Remember to ask for help as I come around.