what is matter? matter is anything that has mass. all objects are made of matter. air, water, a...
TRANSCRIPT
What is Matter?What is Matter?
Matter is anything that has mass. All objects are made of matter. Air, water, a brick, even you are made of matter!
States of matterStates of matter
VIDEO-Clip: http://www.britannica.com/EBchecked/topic/41549/atom
Atomic particles and isotopesAtomic particles and isotopes
Particles smaller than an atom.They may be elementary or composite.
Electrons (elementary)Protons (composite), made of 3 quarksNeutrons (composite), made of 3 quarks
Subatomic particlesSubatomic particles
Over eighty years ago, scientists thought that the atom was the smallest piece of matter.
Atom: the building block of matter
John DALTON (1844)
Solid sphere model
John DALTONJohn DALTON
http://www.etownschools.org/Page/3502
John DALTON’s atomic theoryJohn DALTON’s atomic theory
VIDEO CLIP: http://www.britannica.com/EBchecked/topic/41549/atom
1940 John Thomson1906 Nobel Prize in Physics
John THOMSON discovered the electronsJohn THOMSON discovered the electrons
The Cavendish Laboratory, Cambridge (UK)
Thomson at workThomson at work
A simple cathode ray tube. A simple cathode ray tube.
What could these rays be? What could these rays be?
VIDEO (3:46’) http://www.youtube.com/watch?v=4QAzu6fe8rE
He advanced the idea that cathode rays are really streams of very small pieces of atoms.
Do atoms have parts?Do atoms have parts?JJ Thomson suggested that they do!
J.J. Thomson experimenting
"We have in the cathode rays matter in a new state."
J.J. Thomson TalksJ.J. Thomson TalksAbout the Size of the ElectronAbout the Size of the Electron
To listen to J.J. Thomson speaking on his discovery:
Recording made in 1934. From the soundtrack of the film, Atomic Physicscopyright © J. Arthur Rank Organization, Ltd., 1948.
"Could anything at first sight seem more impractical than a body (the electron) which is so small that its mass is an insignificant fraction of the mass of an atom of hydrogen? --which itself is so small that a crowd of these atoms equal in number to the population of the whole world would be too small to have been detected by any means then known to science."
AUDIO: http://www.aip.org/history/electron/jjsound.htm
Raisin cake model
John THOMSON’s model of the atomJohn THOMSON’s model of the atom
J.J. Thomson theorized that electrons were surrounded by a positively charged material, uniformly distributed.
Ernest Rutherford discovered the nucleusErnest Rutherford discovered the nucleus
1937 Ernest RutherfordNobel Prize Solar system model1908
Rutherford’s experimentRutherford’s experimentThe gold-foil experimentThe gold-foil experiment
VIDEO: http://www.youtube.com/watch?v=Zd6_zVdMgJk
Alpha particle: helium nucleus (4u2+)
Expected results according to…..Expected results according to…..
Thomson’s modelThomson’s model Rutherford’s modelRutherford’s model
Rutherford envisioned the atom as a miniature solar system, with electrons orbiting around a massive nucleus.
Rutherford’s model of the atomRutherford’s model of the atom
Solar system model
What is Matter?What is Matter?
neutronsneutrons
mesonsmesons
Quarks and gluonsQuarks and gluons
Do you think that the quark is the smallest piece of matter or do you think that there
might besomething smaller inside the quark?
You name it!You name it!
You name it!You name it!
The model of atom created by Rutherford shouldn’t exist!
According to classical physics, an electron in orbit around an atomic nucleus should emit electromagnetic radiation (photons) continuously.
The resulting loss of energy implies that the electron should spiral into the nucleus in a very short time (atoms cannot exist!!)
Quantized shell model
1962 Niels BOHR1922 Nobel Prize
Niels BOHR
In 1913 Bohr proposed his quantized shell model of the atom to explain how electrons can have stable orbits around the nucleus.
quantized shell model
Bohr proposed that electrons are restricted to certain fixed (quantized) orbits.
An electron can jump between these orbits by absorbing or emitting a photon with the appropriate precise wavelenght.
Fixed orbits
Bohr's idea was that each discrete orbit could only hold a certain number of electrons. After that orbit is full, the next level would have to be used. This gives the atom a shell structure, in which each shell corresponds to a Bohr orbit
Shell model of the atomShell model of the atom
VIDEO: http://www.britannica.com/EBchecked/topic/41549/atom/48360/Bohrs-shell-model
For working hard with me!For working hard with me!
VIDEO: http://www.britannica.com/EBchecked/topic/41549/atom/48360/Bohrs-shell-model
Electronic configuration of Electronic configuration of different atomsdifferent atoms
VIDEO: http://www.britannica.com/EBchecked/topic/41549/atom/48360/Bohrs-shell-model
Nuclear fissionNuclear fission
VIDEO: http://www.britannica.com/EBchecked/topic/41549/atom/48360/Bohrs-shell-model
Atomic bondsAtomic bonds
VIDEO: http://www.britannica.com/EBchecked/topic/41549/atom/48360/Bohrs-shell-model
Nuclear powerNuclear power