Atomic Theories and Structures

8/11/2019 Atomic Theories and Structures

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Thales

Matter:

water earth air

Leucippus(450 B.C.)

There must ultimately be tinyparticles of water that could not

be subdivided
http://en.wikipedia.org/wiki/File:Leucippe_(portrait).jpghttp://www.google.com.ph/url?sa=i&source=images&cd=&cad=rja&docid=jy7wFg5UWq0qwM&tbnid=Iz3jDBwLlYVIvM:&ved=0CAgQjRwwAA&url=http://www.iep.utm.edu/thales/&ei=O2rZUYDjO8e3rAfL7IC4BA&psig=AFQjCNGC26zk6lJRsCkC5dJ81u1MSCkCuQ&ust=1373289404176707


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Democritus 470370 B.C.

- expanded Leucippus idea

- world made up of empty space and tiny

particles

atomos indivisible

- All forms of matter were divisible into invisible

particles called atoms

Empedocles (440 B.C.)

All matter was composed of four

elements:

Earth, air, water and fire
http://www.google.com.ph/url?sa=i&source=images&cd=&cad=rja&docid=sOALZOJouSHhzM&tbnid=eQtlAFKr6DWnlM:&ved=0CAUQjRw&url=http://mortizjacinto.blogspot.com/2011_06_01_archive.html&ei=SnDZUenGDKqkiAfTiYDACw&psig=AFQjCNH717uvWCM7gGQc4rt5a0qLEu4k8w&ust=1373290930381227http://en.wikipedia.org/wiki/File:Democritus2.jpg


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Heat, cold, moisture and dryness

ex: fire = hot and dry

water = cold and moistair = hot and moist

earth = cold and dry

Endorsed and advanced the Empedocleantheory.

Believed that matter was continuous and

was not made up of smaller particles

hyle

Aristotle (384 - 322 B.C.)
http://en.wikipedia.org/wiki/File:Aristotle_Altemps_Inv8575.jpg


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He offered logical hypothesis about the

existence of atoms by studying certain

experimental observations made by

other scientists concerning chemicalreactions

JOHN DALTON
http://en.wikipedia.org/wiki/File:John_Dalton_by_Charles_Turner.jpghttp://en.wikipedia.org/wiki/File:John_Dalton_by_Charles_Turner.jpg


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Antoine Laurent Lavoisier

When a chemical change occurred

in a closed system, the mass of theproducts after a chemical change

equals the mass of the reactants

before the change. In all tests, the

mass remained constant.

LAW OF CONSERVATION OF MASS OR MATTER

In ordinary chemical reactions, matter is neither

created nor destroyed.
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Joseph Proust

Specific substances always contain elementsin the same ratio by mass

LAW OF DEFINITE PROPORTIONS

LAW OF MULTIPLE PROPORTIONS

AmadeoAvogadro (1811)

Joseph Louis Gay-Lussac (1778-1823)

AVOGADROS LAW OF MOLAR VOLUMES

The ratio of masses of one element that combine

with a constant mass of another element can be

expressed in the ratio of small whole numbers

LAW OF COMBINING VOLUMES
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DALTONS ATOMIC THEORY

1. All matter is composed of

extremely small particles called

atoms.

2. Atoms of a given element are alike

in size, mass and other properties;

atoms of different elements differ

in size, mass and other properties.

3. Atoms cannot be subdivided,

created, or destroyed.

4. Chemical compounds are formed

when atoms of different elements

combine in simple, whole numberratios.

5. In chemical reactions, atoms are

combined, separated or

rearranged.

MODERN MODIFICATIONS OF

DALTONS ATOMIC THEORY

1. Discovery of the sub-atomic

particles of atoms.

2. Discovery of radio-isotopes.

3. Nuclear reactions.

4. Unmodified.5. Unmodified for simple

chemical reactions.


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An atomis the smallest particle of an element that can

exist either alone or in combination with other atoms.

Plum Pudding ModelRaisin Bread Model

Sir J.J. Thompson

Composed of a positively chargedcloud with the electrons distributed /

suspended


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Ernest RutherfordBritish

physicist

Miniature Solar System with

electrons moving around like

planets around the nucleus

Neils BohrDanish physicist

Postulated further that electronscould only move in certain orbits

and has certain energies


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Erwin SchrodingerAustrian physicist

Electrons are described not by the paths

they take but by the regions of space where

they are most likely to be found


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Negative electrical charge (-1)

Mass 9.110 x 10-24g ; Mass in amu =5.486 x 10 -4amu

Discovered by Sir Joseph John Thompson

in 1897

Positive electrical charge (+1)

Mass 1.673 x 10-24g ; Mass in amu = 1.0073

amuDiscovered by Eugene Goldstein (German

physicist) in 1886


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Bears no electrical charge; neutral no

Mass 1.675 x 10

-24

g ; Mass in amu =1.0087 amu

Existence was first predicted by

Rutherford; First evidence of the particle

was obtained by Walter Bothe in 1930and was finally discovered by James

Chadwick


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Is a theory that describes mathematically the wave

properties of electrons and other very small particles

Erwin SchrodingerSchrodinger Wave Equation

-Incorporates both the wavelike and particle-like behavior

of the electrons moving around a nucleus

- opened a way of dealing with the sub-atomic particles -QUANTUM MECHANICS the foundation for modern

quantum theory


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1) sorbital sharp - high probability

of being found rightat the nucleus

itself

- spherical cloud

2) porbital principal - cloud with 2 lobes

on opposite sides

of the nucleus

- has 3 p-orbitals


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Erwin Schrodinger found each atomic orbital can be

identified by four different numbers

-Are numbers used to identify electrons in the different

atomic orbitals

-specify the properties of atomic orbitals and theirelectrons

1. Principal Quantum Number ( n )- indicates the main energy levels surrounding a

nucleus; identifies the shell or energy level to which

the electron belongs

- values of n: 1,2,3 .


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2. Orbital Momentum Quantum Number ( l)

- indicates the shape of an orbital; also the quantum

number that indicates the type of sub-shell (sub-

levels)- s, p, d, and f

- widely known or called as the Azimuthal Quantum

Number

3. Magnetic Orbital Quantum Number (ml)

- quantum number that specifies the individual

orbital of a particular shape / sublevel

- s orbitalsphere centered on the nucleus- p orbital3 orientations


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4. Spin Magnetic Quantum Number ( ms)- indicates the 2 possible states of the spin of an

electron in an orbital

- refers to the relative spin direction of the electron+1/2 and -1/2

Is the arrangement of electrons in atoms

Also known as the Electron Distribution Mnemonics

GROUND STATE

EXCITED STATE


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1. Aufbau Principle

An electron occupies the lowest energy orbital that

can receive it

2. HundsRule

When electrons occupy orbitals of equal energy

levels, an electron occupies each orbital before

there is any pairing

3. Paulis Exclusion Principle

No more than two electrons may occupy any given

orbital


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1S 2S 3S 4S 5S 6S 7S

2p 3p 4p 5p 6p 7p

3d 4d 5d 6d 7d

4f 5f 6f 7f

S < 2

p < 6d < 10

f < 14


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Construct the electronic configuration of the following

elements, determine the number of energy levels with the

# of electrons per energy level and indicate the number of

valence electrons:

1. Cobalt = 27 6. Lead = 82

2. Gallium = 31 7. Tungsten = 74

3. Krypton = 36 8. Zirconium = 40

4. Bromine = 35

5. Antimony = 51


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Atomic Theories and Structures