Chemistry Survey

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Pure substance ~- somposed of only one kind of matter having

uniform and consistant properties,

Mizture ~- contain 2 or more pure substances.

Atome = the smallest particles of matter that can be ecu by

ordinary chemical er physical means,

Molecules - the smallest particle of a pure substance that has

the property of the whole.

Elements - a substance composed of only one kind of atom.

Compounds = pure substance Qampenec of 2 or more atoms combined in

Gefinite proportions.

Chemical reaction ~ a change that produces a new substance.

Physical change - a change that does notproduce a new substance.

Chemical abbreviations and notation

The use of letters to represent each tists atom. The letters chosen

from the element name ~- either modern or ancient.

The use of the arrow to indicate chemical change.

Elestrieal na ature of matter

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Atomic structive

A Behavior of atoms can. bd explained on the basis of an electrical

picture. This picture includes these components.

B. Nuclene of an atom contains nearly all the mass of the element.

It is positively changed.

cent. Electrons are negative parts qh.ag of electricity, tinea are and

varying numbers of electrons outside the nucleus. This number

4nereases one for each new element starting with hydrogen with

one and inoreasing until uranium is reached with a total outside

the nueleus of 92. This number of electrons is known as the

atomic number. They increase in orbits starting with 2 ~- 6 - 0x00A7 -".

D. The mass of the elenents also inerease with Anoreasing atomic num

ber with but few minor exceptions.

E. Each nucleus (iva scsi excepted) has several units of mass ar

a total number of positive charges equal to the no. of units

of mass. Also in the nucleus there are additional electrone.

The no. outside the nucleus (atomic no.), plus those in the

nucleus are equivalent to the total no. of positive charges.

That 18, an element is electrically neutral.

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Atomic Weights

chemical behavior of the @lements is larcely determined

by the no. of elestrons in the outer most orbit outside the

NUCLEUS 6

The Glascifieation of the properties and behavior of the elements

and their compounds can be organized into what.is called the

periedic table.

3. Agoms and molecules are Kinetics, that is they are in motione--"

evidence -- pressure and diffusion of gases.

Gages -

i. Air 18 composed of a mixture of gases ~ mostly (80%) nitrogen and

20% oxygen. |

2, Oxygen ~- discovered by Priestly found to be distomic (two atoms)

therefore O-. Burning is the rapid combination of oxygen with

ether atom8 with the giving off of heat and light. Oxygen can

jombine more Sloyly and 4n such a fashion does not ere off light

(rusting of irenj. Both processes are called oxidation.

Oxygen can be produced by the electrical decomposition of water or

by other chemical action. Properties - colorless odorless gas

heavier than air and supports combustion.

Gas Laws

Boyles plyts paye

Charles pigts pero '

Combined | pi yt = pays

3 nn :lCUC

Absolute Temperature - use centigrade scale as though zero degrees

centigrade were 273 degrees,then zero on thie seale is zero

abgolute. CGentierade ean be changed to Fahrenheit by multiplying

by 5/9 and adding 32. ae

Law of conservation of masa =

No masse oan be destroyed or made. There is just as much maas

produced by a reaction as there goes into it.

Law of definite propertions. |

Atoms combine to form moleoules in ratio of small whole numbers.

Equal no. of molecules of gases at the same a meee and

preseure, cocupy the same volume 22,4 laters `This holds

sereepective of the weight of the gaseous molecule. :

Each clement has a unit velue of mass based on a comparison of the

weight of the element to oxymen as 16 for one atom of oxygen.

Molecular Weights "

The summation of the atomic weights in the molecule. Taking into

account the number of times an atom osoure 4n the moleoule.