Transcript EXAMPLE

Chemistry and Life
The Periodic Table
Atomic Number:
Number of
Protons and
Electrons
Atomic mass:
Mass relative to
Carbon-12
Chemical Bonding

HUGE: ONLY THE ELECTRONS ARE
INVOLVED IN MAKING CHEMICAL
BONDS!!!
More specifically,
the only the one’s
on the outermost
“shell”
Covalent Bond

Covalent bonds are generally when two or
more atoms share one or more pairs of
electrons.
Nonpolar Covalent Bond

when these shared pairs of electrons are
shared EQUALLY!
Polar Covalent Bond

when these shared pairs of electrons are
NOT shared equally!
Common Polar Covalent
Bond???
Ionic Bond
bond formed between oppositely charged
ions. This happens when the stronger atom
steals 1+ electrons from the weaker atom.
 They both have their outer shells filled, so
all is good.

Ions
Cl- is such a beast that it pulls the outer
electron from Na. Now both are happy.
 They are both now ions.

Chlorine
Sodium
Hydrogen Bonds

These are weak bonds that are caused by
the weak positive charge of the hydrogen
atom to other negative atoms.
Solutes and Solvents

Which is the solute and which is the solvent?
Solutes and Solvents

Solute: The stuff the gets dissolved

Solvent: The stuff that does the dissolving
The Mole: A
Measurement of Matter
 OBJECTIVES:
Distinguish
between the
atomic mass of an
element and its molar
mass.
How do we measure items?
You can measure mass,
 or volume,
 or you can count pieces.


We measure mass in grams.

We measure volume in liters.

We count pieces in MOLES.
What is the mole?
We’re not talking about this
kind of mole!
Moles (is abbreviated: mol)
 It is an amount, defined as the
number of carbon atoms in exactly
12 grams of carbon-12.
1
mole = 6.02 x
23
10
of the
representative particles.
 Treat it like a very large dozen
 6.02 x 1023 is called:
Avogadro’s number.




Similar Words for an
amount
Pair: 1 pair of shoelaces
= 2 shoelaces
Dozen: 1 dozen oranges
= 12 oranges
Gross: 1 gross of pencils
= 144 pencils
Ream: 1 ream of paper
= 500 sheets of paper
Examples
Calculate the molar mass of the
following and tell what type it is:
= 78 g/mol gram formula mass
Na2S
= 92 g/mol gram molecular mass
N2O4
C
= 12 g/mol gram atomic mass
Ca(NO3)2 = 164 g/mol gram formula mass
C6H12O6 = 180 g/mol gram molecular mass
(NH4)3PO4 = 149 g/mol gram formula mass

For example

How many moles is 5.69 g of NaOH?

5.69 g




For example

How many moles is 5.69 g of NaOH?
mole 

5.69 g


g 
 We need to change 5.69 grams NaOH
to moles
For example

How many moles is 5.69 g of NaOH?
mole 

5.69 g


g 
 We need to change 5.69 grams NaOH
to moles
 1mole Na = 23 g 1 mol O = 16 g
1 mole of H = 1 g
For example

How many moles is 5.69 g of NaOH?
mole 

5.69 g


g 
 We need to change 5.69 grams NaOH
to moles
 1mole Na = 23 g 1 mol O = 16 g
1 mole of H = 1 g
 1 mole NaOH = 40 g
For example

How many moles is 5.69 g of NaOH?
1 mole 

5.69 g


40.00 g 
 We need to change 5.69 grams NaOH
to moles
 1mole Na = 23 g 1 mol O = 16 g
1 mole of H = 1 g
 1 mole NaOH = 40 g
For example

How many moles is 5.69 g of NaOH?

5.69 g


1 mole 
 = 0.142 mol NaOH
40.00 g 
We need to change 5.69 grams NaOH
to moles
 1mole Na = 23 g 1 mol O = 16 g
1 mole of H = 1 g
 1 mole NaOH = 40 g
Chemical Reactions
An Overview
How do you know a reaction has
taken place?
A new substance is formed
 Heat is produced or absorbed
 A gas is released

How to write a reaction

Example: Hydrogen gas + Oxygen gas =
Water
Here ya go!

H2
+
Reactants
H2 and O2
O2

H 2O
Products
H 2O
Types of Reactions

Synthesis: 2 or more substances combine
to make a new one.

Example: H2
+
O2

H 2O

Decomposition: 1 substance is broken into 2
or more substances

H2O  H2 + O2

Single Displacement: One element replaces
another element.

Cu + AgNO3  CuNO3 + Ag
The Silver replaced the Copper
 Demo


Double Displacement: Two elements switch
places. Two Ions are mixed together and a
precipitate is formed

A precipitate is an insoluble compound
formed during the reaction

PbNO3 + KI  PbI2 + KNO3
OXIDATION/ REDUCTION
STUFF
OXIDATION: LOSS OF ELECTRONS
 EXAMPLE: SODIUM IN THE PRESENCE
OF CHLORINE
 REDUCTION: GAIN OF ELECTRONS
 EXAMPLE: CHLORINE IN THE PRESENCE
OF SODIUM
 ***THE TWO REACTIONS ALWAYS
OCCUR TOGETHER!!

What the heck is pH?

ACID: PROTON DONOR (BASICALLY, A
DONATION OF H+ IONS.

WHAT IS H+ REALLY?

BASE: PROTON ACCEPTOR; RELEASES –
OH IONS
More on pH…
IT IS SIMPLE THE LOG OF THE INVERSE
OF THE HYDROGEN ION
CONCENTRATION.
 (NOW, IN ENGLISH): THE LOWER THE
pH, THE HIGHER THE [H+], THE HIGHER
THE pH, THE LOWER THE [H+].
 EACH SCALE NUMBER OF pH
REPRESENTS A TENFOLD INCREASE OR
DECREASE IN THE [H+].


Answer: 100x (10x10)
EXAMPLE: HOW MUCH MORE ACIDIC IS
pH=2 AS COMPARED TO pH=4?
Answer= 10 x 10 = 100
BUFFERS

BUFFERS: THEY RESIST A CHANGE IN
pH OF A SUBSTANCE BY EITHER
ACCEPTING OR DONATING H+ IONS IN
THE PRESENCE OF AN ACID OR A BASE