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Chapter Three
Basic Chemistry

3-1 Atomic Theory of Matter

TOPICS

Atoms, Elements, and Compounds

Structure of Atoms

Isotopes

Radioactive Isotopes

 

Atoms, Elements, Compounds

Basic chemistry is needed

Building blocks - atoms

smallest matter

Elements - only one kind of atom

Fe, O

112 different elements

periodic table

Compounds

two or more kinds of atoms combined in definite proportions

O 2, C O 2

 

 

Shorthand and symbols

Abbreviations

English

Latin

first letter capitalized

second letter lower case

Look at figure 3-3 page 35 of text

 

Structure of Atoms

2500 years ago, ancient Greece

recent research finds atoms consisting of smaller particles

nucleus

protons, + charge, inside nucleus, mass = 1 amu

neutrons, no charge, inside nucleus, mass = 1 amu

atomic number = number of protons

mass number = sum of protons + neutrons

electrons, - charge, outside nucleus, mass less than + or neutron

 

Isotopes

Atoms of an element may have different numbers of neutrons.

Are not exactly alike

behave the same chemically

all elements have isotopes

same atomic number, different mass numbers

16 O, 17 O, 18 O or Oxygen - 18

 

Radioactive Isotopes

Isotope nuclei are unstable

emits charged particles

radiation that can not be predicted

Radioactivity = nuclear process

discovered in 1896

elements of Uranium

Radioisotopes

detect abnormalities, treatment cancer, study chemical reactions ( tracers )

Oxygen - 18 not radioactive

study process of photosynthesis

 

3-2 Chemical Bonding and Chemical Reactions

TOPICS

Covalent Bonds

Ionic Bonds

Chemical Formulas

Chemical Reactions

 

Covalent Bonds

Sharing of a pair of electrons by two atoms creates a force of attraction that holds the atoms together.

When a chemical bond is formed by sharing of electrons, it is covalent.

Electron structure of elements

oxygen, 8 protons, 8 electrons, 8 neutrons

O2 , double bond

diatomic molecule

H, O, N, Cl, F

 

Ionic Bonds

Ion - atom that has an excess charge

Ionic bond - the force of attraction between two ions.

Na + Cl2 -----> 2NaCl

Na, 11 protons, 11 electrons ( + 1 )

Cl, 17 protons, 17 electrons ( - 1 )

Sodium Chloride - crystal form

 

Chemical Formulas

Every compound consists of atoms combined in definite proportions.

Chemical formula

symbol

subscripts

Glucose = C6H12O6

 

Structural Formulas

Is a kind of chemical formula

shows only the number and kind of atoms in a molecule but also how the atoms are bonded together to one another.

H - C = C - H Acetylene, triple bond

H

O water

H

go to page 43 of the text

 

Chemical Reactions

Chemical bonds can be broken

atoms can form new bonds in new combinations

Reactants

arrow -----> means produces or yields

Products

example: hydrogen + oxygen -----> water

H2 + O2 -----> H2O

balance the above equation ( page 44 )

 

Law of Conservation of Mass

States: that mass can be neither created nor destroyed in chemical reactions.

Because atoms have mass.

They are just rearranged.

A balanced equation for the breakdown of glucose.

C6H12O6 + 6O2 -----> 6CO2 + 6H2O

 

3-3 Mixtures

Physically mixed

different substances retain physical properties

Sodium chloride and iron fillings

Homogeneous mixture - same throughout

air

N, O, CO2, water vapor and others

heterogeneous mixture - different throughout

 

Solutions

Any homogeneous mixture can be called a solution

used for mixtures that are liquids.

solvent - dissolves the solute

solute - dissolved in the solvent

may be solids, liquids, or gases

most common solute is water

universal solvent

dissociation - breaks into sodium and chlorine ions

NaCl -----> Na+ + Cl--

 

Suspensions

A mixture that separates on standing

sand in water

shake the container of sand and water, let the container sit for a period of time, the sand will settles out.

Gravity will cause the sand to settle.

 

Colloidal Dispersions

Another type of mixture

Colloidal Dispersions

the particles are larger than the molecules or ions but too small to settle out.

Medium does not to be a liquid, can be a gas or solid.

Examples

smoke - carbon dioxide in air.

Milk, mayonnaise, whipped cream ( gas in a liquid )

 

3-4
Acids, Bases, and Salts

Acids

Any compound that produces hydrogen ions in solution.

Hydrogen covalently bonds to another atom or group of atoms.

HCl - hydrochloric acid

important to life activities

dissolved in water: HCl -----> H+ + Cl--

 

Bases

Compounds that produce hydroxide ions when dissolved in water

dry state many are ionic compounds

NaOH - sodium hydroxide

NaOH -----> Na+ + OH --

 

Neutralization

Process of reacting an acid and a base to produce a neutral solution.

Neither an acid or a base.

H + + OH - ----> HOH ( or H2O )

Acid neutralizes a base

Base neutralizes an acid

 

Salts

Ionic compound produced from neutralization reaction between and acid and base

NaCl = Sodium Chloride

HCL + NaOH -----> Na + + Cl - + HOH

Hydrochloric acid plus sodium hydroxide yields sodium plus chlorine and water.

Provides essential ions for body processes

 

The pH Scale

pH = power of Hydrogen

acids = very acidic 0 to 6.9

neutral = 7.0

base = 7.1 to 14 very basic

indicators - shows acid, base, neutral, actual pH value

litmus paper, red and blue

methyl orange = turns yellow to red ( moderate acid )

phenolphthalein = turns red ( base )

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