Notes lab 04a the atom complete notes

The Atom

Notes

The AtomFrom the Greek prefix A- meaning

“not”And the Greek Root –tomos meaning

“cut”Means “uncuttable”

The ancient Greeks wanted to learn about the smallest particle of matter

The AncientsDemocritusAristotle

Democritus

Democritus Believed that all matter consisted of

extremely small particles that could not be divided.

He called these particles atoms (from the Greek “ατοµος”, meaning “uncut” or “indivisible”).

Democritus

He believed there were different types of atoms with specific sets of properties.

The atoms in liquids, for example, were round and smooth

The atoms in solids were rough and prickly

Aristotle

Aristotle

He did not think there was a limit to the number of times matter could be divided

He thought that all substances were built up from only four elements

EarthAirFireWater

The ModernsDaltonThomsonRutherfordBohrSchrodinger & Heisenberg

Dalton

Dalton’s Model of the Atom

Created the 1st Atomic TheoryHis theory explained why the

elements in a compound always bond in the same way


He proposed the theory:All matter is made up of individual particles, called atoms, which cannot be divided.


All elements are composed of same atoms


All atoms of the same element have the same mass


Atoms of different elements have different masses.


Compounds contain atoms of more than one element.


In a particular compound, atoms of different elements always combine in the same way

The Dalton Model

The Dalton Model

Video:http://www.youtube.com/watch?v=HFF-2w

yyTKc&feature=results_video&playnext=1&list=PLF3AEE12BDB1E3858

http://www.youtube.com/watch?v=HFF-2wyyTKc&feature=results_video&playnext=1&list=PLF3AEE12BDB1E3858



J. J. Thomson

J. J. Thomson’s Model of the Atom

Thomson’s experiments with beams of charged particles in a sealed glass tube led him to the conclusion that atoms were made of even smaller particles

J. J. Thomson’s Model of the Atom

Thomson reasoned:If the charge of an atom is neutral, the atom must contain equal amounts of both positive and negative charges

The Thomson Model

Thomson said that negative charges were evenly scattered throughout an atom filled with a positively charged mass of matter.

The Thomson Model

Called the “Plum Pudding Model” after a popular dessert of the time

The Thomson Model

Video: http://www.youtube.com/watch?v=JwdGFZ

A3WOs

http://www.youtube.com/watch?v=JwdGFZA3WOs

http://www.youtube.com/watch?v=JwdGFZA3WOs

Rutherford

Rutherford’s Model of the Atom

Rutherford discovered that uranium emits fast-moving particles with a positive charge. He called them alpha particles.


In an experiment he charted the path of alpha particles after they passed through a thin layer of gold foil and a number of the particles were deflected.

Many more than expected, sometimes by more than 90°.


Proved most of an atom is actually empty space!


The positive charge of an atom must be concentrated in a very small central area that he called the nucleus.


Further experiments determined that the positive charge of an atom is by the number of protons in the nucleus.


Each proton has a charge of +1.

The Rutherford Model

Rutherford’s Model of the Atom and Gold Foil Test

Rutherford’s Model

VideoNucleus of an Atom

Niels Bohr

The Bohr Model of the Atom

In Bohr’s model, electrons move with constant speed in fixed orbits around the nucleus, like planets around a sun.


Electrons gain or lose energy when they move between orbits or energy levels. Energy levels are like stairs on a staircase or shelves in a bookshelf


Evidence for discrete, unique energy levels comes from the light given off when energy is added to the atoms of an element (such as when fireworks explode or electricity is added to a neon light).


No two elements have the same set of energy levels, so the emission pattern can be used to identify the element.


Video”The Niels Bohr Rap

The Bohr Model

Schrodinger & Heisenberg


These scientists discovered that electrons are less predictable than in Bohr’s model of fixed orbits.


Atoms gain or lose energy. when electrons move from one energy level to another


They use an electron cloud model to show the most likely locations for electrons as they move around the nucleus.


The electron cloud represents all the orbitals in an atom.


An orbital is a region of space around the nucleus where an electron is likely to be found.


Orbitals come in different sizes, shapes, and locations


An electron configuration is the arrangement of electrons in the orbitals of an atom.


The most stable electron configuration is the one in which the electrons are in orbitals with the lowest possible energies

Video :Change of Atom-Dalton, Thomson,

Rutherford, Bohr

The Electron Cloud Model

The Electron Cloud Model

Video:electron cloud model

The Nature of ScienceEach scientist was correct for his

time and ability to make observations.

As improvements in technology came about, each later scientist proved the previous scientist(s) slightly incorrect.

The Nature of Science

Now there is a totally different model of the atom from the first model presented by Dalton.

Only some of the theories of each scientist remain.

In general…


As the ability to make better observations improves, the new knowledge may support or disprove what we have held to be true.


As the ability to make better scientific observations improved,

Atomic theory changed over timeScientists improved upon

previous scientists theories by proving the correct and disproving the incorrect


From Dalton’s solid sphere that bonded the same way all the time…

To Thomson’s “Plum Pudding “ model of equal amounts of positive and negative charges…


Then Rutherford proved that the equal charges were separated by vast space in a nucleus and orbiting electrons

And Bohr gave order to the orbiting electrons saying that they maintained constant orbits


.

Technology

Notes lab 04a the atom complete notes