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 of the representative particles.  Treat it like a very large dozen  6.02 x 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: Na 2 S N 2 O 4 C Ca(NO 3 ) 2 C 6 H 12 O 6 (NH 4 ) 3 PO 4 = 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?

For example How many moles is 5.69 g of NaOH? l We need to change 5.69 grams NaOH to moles

For example How many moles is 5.69 g of NaOH? l We need to change 5.69 grams NaOH to moles l 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? l We need to change 5.69 grams NaOH to moles l 1mole Na = 23 g 1 mol O = 16 g 1 mole of H = 1 g l 1 mole NaOH = 40 g

For example How many moles is 5.69 g of NaOH? l We need to change 5.69 grams NaOH to moles l 1mole Na = 23 g 1 mol O = 16 g 1 mole of H = 1 g l 1 mole NaOH = 40 g

For example How many moles is 5.69 g of NaOH? l We need to change 5.69 grams NaOH to moles l 1mole Na = 23 g 1 mol O = 16 g 1 mole of H = 1 g l 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! H 2 + O 2  H 2 O Reactants Products H 2 and O 2 H 2 O

Types of Reactions Synthesis: 2 or more substances combine to make a new one. Example: H 2 + O 2  H 2 O

Decomposition: 1 substance is broken into 2 or more substances H 2 O  H 2 + O 2

Single Displacement: One element replaces another element. Cu + AgNO 3  CuNO 3 + 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 PbNO 3 + KI  PbI 2 + KNO 3

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)

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