Atoms vs. MoleculesGive some examples of molecules

Water (H2O)

Carbon dioxide (CO2)

Give some examples of atoms Hydrogen (H)Oxygen (O)Carbon (C)

Atoms are the smallest particle of an element that still have the same properties as the element.

How are atoms and molecules related?

Molecules are made up of atoms chemically bonded together.

Individual atoms and molecules are too small to be seen!

Subatomic ParticlesSubatomic particles are particles

that are smaller than atoms, and are found in atoms.

There are 3 different subatomic particles:

ProtonsPositive charge/found in the atom’s

nucleusNeutrons

Neutral (no charge)/found in the atom’s nucleus

ElectronsNegative charge/found outside the

atom’s nucleus

Atoms usually have an equal number of protons (+) and electrons (-) and are electrically neutral.

Atoms can gain or lose electrons and are called ions.

Atoms thatlose electrons (-) develop a positive

charge.

→

gain electrons (-) develop a negative charge.

→

●

# Electrons(-) = # Protons(+) 6 Electrons(-) 7 Protons(+)

●

●

# Electrons(-) = # Protons(+) 8 Electrons(-) 7 Protons(+)

HYDROGEN ATOMS Hydrogen atoms have one proton and one

electron.

When a hydrogen atom loses its electron, it becomes a hydrogen ion and is symbolized as H+.

WATERFormula: H2O Picture:

A water molecule is made up of two hydrogen atoms, and one oxygen atoms.

Water molecules can dissociate (split into ions):H2O H+ + OH-

Hydrogen ion + Hydroxide ion

The electron (-) from one of the hydrogen (H) atoms stays with the OH when the water molecule dissociates.

For every one H+ there is one OH-.

Acids and Bases

Water can dissociate- separate into ions.H2O H+ + OH-

(missing e-) (extra e-)

H+ =Hydrogen ionOH- =Hydroxide ion

The H+ can then combine with another water molecule

H+ + H2O H3O+

to make an Hydronium ion- H3O+

So we can say that water

[ H+] = [OH-]Or [H3O+] = {OH-][concentration of] H2O H+

OH- H3O+

ACIDSContain hydrogen (in their formula)Contain hydrogen ions (H+), hydrogen atoms

with a positive charge, that combine with nonmetallic elements or ions.

React with metals to produce hydrogen gasCan be dangerous/corrosiveThose that are safe to taste, taste sourDo not feel slippery

Examples of some Acids:Acetic acid HC2H3O2 Boric Acid H3BO3

Carbonic Acid H2CO3 Hydrochloric acid, HCl

Sulfuric acid, H2SO4 Citric acid H2C6H5O7 (C6H7O8)

Nitric acid HNO3 Phosphoric acid H3PO4

Common examples/Uses:Ascorbic Acid = Vitamin CAcetic Acid = VinegarCarbonic Acid = Carbonated BeveragesCitric Acid = in Citrus FruitHydrochloric Acid = Stomach Acid

When an acid is mixed with water it dissociates(splits into ions).

HCl + H2O

H+ Cl- + H2O

We can say that acids give off H+ or increase the concentration of H+

BASESContain hydrogen and oxygen (OH) (in their

formula)Produce hydrogen and oxygen combined into a

hydroxide ion (OH-)Are formed and hydroxide ions (OH-) are

released when some nonmetals are placed in water

Can be dangerous chemicals/corrosiveThose that are safe to taste, taste bitterFeel slippery

Examples of some Bases:Magnesium Hydroxide Mg(OH)2

Calcium Hydroxide Ca(OH)2Sodium Hydroxide NaOHAmmonium Hydroxide NH4OH

Ammonia NH3

Common Examples /Uses:Antacids Cleaners

When a base is mixed with water it dissociates(splits into ions).

KOH + H2O

K+ + OH-

We can say that bases:Give off OH- or Increase the amount of OH-

(substances that accept (decrease) the amount of H+ are considered bases also) (NH3 + H+ → NH4

+ )

MEASURING THE STRENGTH OF ACIDS AND BASESThe pH scale is used to measure the strength of acid and

bases.Compares the [H+] to the concentration of [OH-].[H+] [H3O+] > [OH-] [H+]=[OH-] [OH-]>[H+]

[H3O+]

[OH-] < [H+][H3O+] [H+] [H3O+] < [OH-]

0---1---2---3---4---5---6---7---8---9---10---11---12---13---14

Acid Neutral Base More H3O+ More OH-

Less OH- Less H3O+

0---1---2---3---4---5---6---7---8---9---10---11---12---13---14 (H+) Acid Neutral Base (OH+)Every unit on the pH scale is a Ten times change in (H+/OH-) Comparing Solutions:pH 3 vs. pH 7pH 3 solution has more H+ by a factor of 105 (10 x 10 x 10 x 10 x 10)

100,000 times more H+ pH 3 solution has less OH- by a factor of 105 (10 x 10 x 10 x 10 x 10)

100,000 times less OH- pH 12 vs. pH 5pH 12 has more OH-

less H+ by 107 TIMES

pH 5 has more H+ less OH-

by 107 TIMES

NEUTRALIZATIONWhen acids are mixed with bases they neutralize

each other.The pH of the mixture will be somewhere between

the pH of the acid and the pH of the base.Mixing a strong acid (pH= 2) with a strong base

(pH=12) will result in a pH of about 7. (12 + 2 ÷ 2)Mixing a weak acid (pH= 6) with a weak base (pH=8)

will result in a pH of about 7. (6 + 8 ÷ 2)Mixing a strong acid (pH= 2) with a weak base

(pH=8) will result in a pH of about 6. (10 + 2 ÷ 2)Mixing a weak acid (pH= 6) with a strong base

(pH=10) will result in a pH of about 8. (10 + 6 ÷ 2)

INDICATORSSubstances (solids, liquids) that can be used

to determine if something is acidic or basic (alkaline).

Indicators change color depending on the acidity of the solution.

Have we used any indicators this year in lab?Phenolphthalein and red litmus paper

INDICATORSLiquids

Bromthymol Blue…………Phenolphthalein………….Phenol Red…………………..Universal……………………..

PaperBlue Litmus………………….Red Litmus…………………..pH paper………………………

in Acid in BaseYellowBlueColorless PinkYellow Red R O Y G B I V

Red BlueRed Blue R O Y G B I V

Color

Water can act as an acid or a base…..

HCl + H2O →H3O+ + Cl-

Water is acting as a base by accepting a H+.

NH3 + H2O → NH4+ +

OH-

Water is acting as an acid by donating an H+.