02/03/15
O To Do:
O Bell Work:
O Bell Work
O Copy To Do list in
O Hydrated Crystal Lab
Agenda.
O Note Quiz –
complete the
handout and return
to Ms. M.
O Bonding
O Chemical Reactions
O Practice WSs
O Complete foldable for
Ch. 8.2 – Types of
Chemical Reactions
Announcements
O Foldable
O 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 Equations
O Notes will go on pg. 70 of your SIN.
O Remember to set up Cornell notes!
Ionic Bonds
O 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 Bonds
O 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 Bonds
O 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 Bonds
O 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 Bonds
O 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 & light
O Heat and/or light is given off when two compounds
are mixed.
O Color change
O Production of gas
O Formation of a precipitate
O Precipitate – when a solid is produced in a solution
from a chemical reaction.
Chemical Equations
O 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 Equations
O Diatomic Compounds – Look up a definition in your
book!
O Why do we need to keep this in mind?
Chemical Equations
O 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:
Starting material goes on the left.
Ending material on the right.
Use a + sign to indicate something is mixing.
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)
O
O
O
O
Chemical Equations
O 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 Equations
O 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 Equations
O Take what we know about chemical formulas to
figure out how the mass was calculated below.
Chemical Equations
O Balancing Equations:
O You have your equation:
CH4 + O2
CO2 + H2O
O Is this equation balanced?
Chemical Equations
O 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.