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 1023 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:
Na2S
N2O4
C
Ca(NO3)2
C6H12O6
(NH4)3PO4
= 78 g/mol gram formula mass
= 92 g/mol gram molecular mass
= 12 g/mol gram atomic mass
= 164 g/mol gram formula mass
= 180 g/mol gram molecular mass
= 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?
5 69. g mole
g
We need to change 5.69 grams NaOH to moles
For example
How many moles is 5.69 g of NaOH?
5 69. g mole
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?
5 69. g mole
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
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
40.00 = 0.142 mol NaOH
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 + O2 H2O
Reactants Products
H2 and O2 H2O
Types of Reactions
Synthesis: 2 or more substances combine to make a new one.
Example: H2 + O2 H2O
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+].
EXAMPLE: HOW MUCH MORE ACIDIC IS pH=2 AS COMPARED TO pH=4?
Answer: 100x (10x10)
Answer= 10 x 10 = 100
Answer: 100x (10x10)Answer: 100x (10x10)
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
