Introduction of Chemistry

Chemistry, a branch of physical science, is the study of the composition, properties and behavior of matter. As it is a fundamental component of matter, the atom is the basic unit of chemistry. Chemistry is concerned with atoms and their interactions with other atoms, with particular focus on the properties of the chemical bonds formed between species. Chemistry is also concerned with the interactions between atoms or molecules and various forms of energy.

Branches of Chemistry

• Organic Chemistry - the study of carbon and its compounds; the study of the chemistry of life.

• Inorganic Chemistry - the study of compounds not-covered by organic chemistry; the study of inorganic compounds or compounds which do not contain a C-H bond. Many inorganic compounds are those which contain metals.

• Analytical Chemistry - the study of the chemistry of matter and the development of tools used to measure properties of matter.

• Physical Chemistry - the branch of chemistry that applies physics to the study of chemistry. Commonly this includes the applications of thermodynamics and quantum mechanics to chemistry.

• Biochemistry - study of the chemistry of biologically important elements and compunds.

History of Chemistry

• Pre-Historic Man - beginning of chemistry when prehistoric man used fire to do crude metallurgy and to make pottery and bricks. First metal used were gold, copper and silver.

• 400 B.C. - beginning of chemistry as a science when the four-element theory was proposed (earth, air, fire, water). Aristotle proposed that there were also four fundamental properties - hot, cold, wet, dry.

• First Century - combination of the arts of the Egyptians and the philosophical speculations of the greeks form the beginning of a body of chemical knowledge. The first book of chemistry was written in Egypt (Chemistry meant "Egypt Art"). The beginning of alchemy in China.

• Twelfth Century- alchemy reached Europe. Alchemy - science concerned with transmutations of one element into another. (Proponents hoped to change base metals, such as iron and copper into gold)

• Sixteenth and Seventeenth Century - chemistry applied to medicine. Study of gases begun. First textbook of chemistry was written in 1597. Robert Boyle studied gases and criticized the basic ideas of alchemy in his book "The Skeptical Chemist".

• Eighteenth Century - Phlogiston Theory was proposed by George Ernst Stahl based on earlier theories of Johann Becher (Phlogiston is a substance in combustible material that is given off when the material burns). Carl Scheele, Joseph Priestly, Joseph Black and Henry Cavendish worked on gases. Careful quantitive work of Antoine Laurant Lavoisier (father of modern chemistry).

• Nineteenth and Twentieth Century - John Dalton proposed the atomic theory. The development of the periodic law and periodic table  was constructed by Dmitri Mendeleev. Further development and application of these theory/ theories. 

Significant Figures

- are digits used to establish the value of a certain number or measurement.

A Rules of Determining the Number of Significant Figures:

1. All nonzero digits are "always significant".
2. Leading zeros are "never significant". (leading zeros are zeros before nonzero digits)
3. Captive zeros are "always significant". (captive zeros are zeros between nonzero digits)
4.  Trailing zeros are may or may not be significant. Trail zeros are "significant only" if the number has decimal point.

Laboratory Apparatus

• Beaker - a liquid-measuring container
• Burets - measures volume of solution
• Clay Triangle - a wire frame with porcelain used to support a crucible
• Wire Gauze - used to spread heat of a burner flame
• Test Tube - used as holder of small amount of solution
• Forceps - holds or pick up small objects
• Graduated Pipet - measures solution volumes
• Condenser - used in distillation
• Crucible - used to heat a small amount of a solid substance at a very high temperature
• Funnel - used to transfer solids and liquids without spilling
• Thermometer - measures temperature
• Balance - measures mass of material
• PH meter - measures acidity of solutions
• Centrifuge - separates materials of varying density
• Pipet - used to transfer measured small substances into another vessel
• Droppers - for addition of liquids, drop by drop
• Glass Funnels - for funneling liquids from one container to another, or for filtering when equipped with filter paper.
• Graduated Cylinders - for measurement of an amount of liquid. The volume of liquid can be estimated to the nearest 0.1 mL with practice.
• Ring Stand (with rings or clamps) - for holding pieces of glassware in place.
• Test Tubes - for holding small samples or for containing small-scale reactions
• Test Tube Holders - for holding test tubes when tubes should not be touched
• Tongs - similar function to forceps, but are useful for larger items
• Volumetric Flask - to measure precise volumes of liquid or to make precise dilutions.
• Wash Bottles - for dispensing small quantities of distilled water.
• Watch Glasses - for holding small samples or for covering beakers or evaporating dishes.
• Wire Gauze on a ring - supports beakers to be heated by Bunsen burners.
• Erlenmeyer Flask - used to heat and store liquids.
• Florence Flask - used for heating substances that need to be heated heavily. (used for distillation)
• Bottles - can be used for storage, mixing and for displaying.
• Magnifying Glass -  make objects appear larger than they are.
• Stirring Rod - manually stir solutions, assist in pouring liquids, transfer a single drop of solution.
• Ring Clamp - connect to a ringstand, provide a stable elevated platform for a beaker to be heated.
• Test Tube Rack - to hold test tube during an investigation.
• Spatula - used like a spoon or instrument for scooping material out of a container.
• Safety Goggles - to protect your eyes against burns or cuts. 
• Mortar and Pestle - used to crush solids into powder.
• Petri Dish - used especially for cultures of bacteriology.
• Test Tube Brush - to clean inside of test tubes.
• Stopper - used to close containers to avoid spillage or contamination.
• Paper Towel - essential to lab; used in almost every lab.
• Well Plates - used when we want to perform many small scale reactions at one time.
• Beam Balance - balance of great precision used in quantitative chemical analysis.
• Triple Beam Balance - to measure mass (weight) of substances or objects.
• Bunsen Burner - source of heat
• Evaporating Dish - used for heating stable solid compounds and elements.
• Lighter - used to light lab burners.
• Microscope - used for making enlarged images of minute objects.
• Cover Slip - used to cover a specimen (or sample) on a slide.
• Litmus Paper - used to determine whether a liquid is an acid or a base.
• Slide - to hold a specimen (sample) for viewing through a microscope.  

Scientific Measurements (SI Base Units)

Physical Quantities                   Unit                 Abbreviation of Unit

Length                                   Meter                           m
Mass                                   Kilogram                         kg
Time                                    Second                           s
Temperature                          Kelvin                           K
Amount of Substance               Mole                           mol
Electric Current                     Ampere                          A
Luminous Intensity               Candela                         cd

SI Prefixes

Prefixes                         Symbol                        Multiplier

tera                                  T                            1 x 10^12
giga                                  G                              10^9 
mega                                M                              10^6 
kilo                                   k                               10^3
hecto                                h                               10^2
deka                                da                              10^1
deci                                  d                              10^-1
centi                                 c                              10^-2
milli                                 m                              10^-3
micro                                u                               10^-6
nano                                 n                              10^-9
pico                                  p                             10^-12
femto                                f                             10^-15

Other Conversion Factors

Celsius = Fahrenheit - 32                            1 atm = 760 mmHg
              -----------------                           
                   1.8                                      1 atm = 760 torr

Fahrenheit = 1.8 ( Celsius + 32 )                  1 atm = 14.7 psi

Kelvin = Celsius + 273                                1 atm = 101325 Pa

Common Conversion Factors

    Length:                 Mass:                    Volume:                     Time:
1 m = 100 cm        1 kg = 1000 g         1 L = 1000 mL          1 hour = 60 min
1 m = 39.37 in       1 kg 2.2 lbs            1 mL = 1 cm^3         1 min = 60 sec
1 in = 2.54 cm       1 g = 1000 g 
1 ft = 12 in           1 g = 1,000,000 ug
1 mi = 1.6 km
1 km = 1000 m

Mole

Mole contains 602,000,000,000,000,000,000,000 or 6.02 x 10^23 particles. This number is known as the Avogadro's number (abbreviated N) in honor to Amadeo Avogadro. A mole is defined as the number of atoms. 12.0 grams of carbon -12.

Atoms and Moles

1 mole = 6.02 x 10^23 atoms

1 element = 6.02 x 10^23 atoms

1 mole o a compound = 6.02 x 10^23 molecules

Molecule and Atom

Molecule - is the smallest particle of a covalent compounds.

Atom - defined as the smallest particle of an element.

Formula Units and Moles

For example:
    Each formula unit of NaCl contains 2 ions, 1 Na (cations) + 1 Cl (anions)
   
    1 mole of a cupd = molar mass

Mole Conversion

1 mole of element = atomic mass / weight
(If whole number: mass number)

1 mole of a compound = molar mass / molecular weight

How will you know when the element/elements is a:

Formula Units: Metal and Non-metal / Not same elements

Atoms: 1 element only

Molecules: 2 same elements 

Chemical Change

- a change in which one or more substances are converted into different substances. Heat and light are often evidence of a chemical change.

Recognizing Chemical Change

1. ENERGY is absorbed or released (temperature changes hot/cold)
2. COLOR CHANGES
3. FORMATION OF PRECIPITATE - a solid that separates from solution.
4. IRREVERSIBILITY - not easily reversed. But, there are examples of these that are not chemical = boiling bubbles, etc. 

Mixtures

- are a physical blend of at least two substances; have variable composition

THEY CAN BE EITHER:

1. Heterogeneous - the mixture is not uniform in composition 

• chocolate chip cookie, gravel, soil

   2.. Homogeneous - same composition throughout; called "solutions"

• kool-aid, air, salt water

Every parts keeps it's own properties

Solutions Are Homogeneous Mixtures

• can occur between any state of matter: gas in gas; liquid in gas; gas in liquid; solid in liquid; solid in solid (alloys) etc. 

• Thus, based on the distribution of their components, mixtures are called homogeneous or heterogeneous.

Phase

- used to describe any part of a sample with uniform composition of properties.

- a homogeneous mixture consists of a single phase.

-a heterogeneous mixture consists of two or more phases.

Separating Mixture (some can be separated by physical means)

• Filtration - separates a solid from the liquid  in a heterogeneous mixture (by size).

• Paper Chromatography - separates components of dyes such as ink.

• Distillation - takes advantage of different boiling points.

Substances are:

a.) elements

b.) compounds

Elements

- simplest kind of matter

- cannot be broken down any simpler and still have properties of that element.

- all one kind of atom

Compounds

- are substances that can be broken down only by chemical methods

- when broken down, the pieces have completely different properties than the original compound.

- made of two or more atoms, chemically combined (not just a physical blend)

Compound Vs. Mixture

            Compound                   Vs.                       Mixture

*Made of one kind of material           *Made of more than one kind of material

*Made by a chemical change             *Made by a physical change 

*Definite composition                      *Variable composition  

Elements Vs. Compounds

• Compound can be broken down into simpler substances by chemical means, but elements cannot.

• A "chemical change" is a change that produces matter with a different composition than the original matter.

Properties Of Compounds

• Quite different properties than their component elements.

• Due to a chemical change, the resulting compound has new and different properties:

- Table sugar : carbon, hydrogen, oxygen

- Sodium Chloride : sodium, chlorine 

- Water : hydrogen, oxygen

Symbols and Formulas

• Currently there are 117 elements

• Elements have a 1 or 2 letter symbol, and compounds have a formula.

• An element's first letter is always capitalized; if there is a second letter, it is written lowercase: B, Ba, C, Ca, H, He.

• Some names come from Latin or other languages 

Chemical Changes

• The ability of a substance to undergo a specific chemical change is called a chemical property 

- iron plus oxygen forms rust, so the ability to rust is a chemical property of iron.

• During a chemical change (also called chemical reaction), the composition of matter always changesa

Chemical Reactions

• Reactants - the stuff you start with.

• Products - what you make.

- The products will have new properties different from the reactants you started with.

-Arrow point from the reactants to the new products.

Conservation Of Mass

- during any chemical reaction, the mass of the products is always equal to the mass of the reactants.

- all the mass can be accounted for:

• Burning of wood results in products that appear to have less mass as ashes; where is the rest.
• Law of conservation of mass