Discovery of sub-atomic particles , Chemistry

Assignment Help:

DISCOVERY OF SUB-ATOMIC PARTICLES

The atomic theory of the Greek philosophers, Leucippus and Democretus (400 B.C.) held that continued subdivision of matter would ultimately yield atoms which would not be further divided. The word 'atom' is derived from the Greek word, aromos, which means "uncut" or indivisible. Dalton (1808) based his atomic theory on the ideas of Democretus and was able to explain the laws of chemical combination.

Toward the end of nineteenth century, it began to appear that the atom itself might be composed of even smaller particles. This discovery was brought about by experiments with electricity. Attempts to pass a high voltage electric current through gases under reduced pressure led to Julius Plucker's discovery (1859) of cathode rays, Fig. 1.1. The cathode rays stream from the negative electrode, which is called the cathode. These rays consist of negatively charged particles which travel in straight lines. The cathode rays give off flashes of light, when they strike a screen coated with substances like zinc sulphide. The picture tubes in television sets and computer monitors, function on this principle.


Related Discussions:- Discovery of sub-atomic particles

Show sulphide minerals, Q. Show Sulphide Minerals? In these minerals me...

Q. Show Sulphide Minerals? In these minerals metals are present as their sulphides. For example, iron pyrites (FeS 2 ), calcocite (CU 2 S), chalcopyrite (CuFeS 2 ), zinc blende

What are ferrites, What are ferrites? Ferrites are ceramic compounds c...

What are ferrites? Ferrites are ceramic compounds containing trivalent metal having three valence electrons, iron and oxide of divalent element i.e. metals having two free ele

Elementary composition of the compound, In early Greece, water was consider...

In early Greece, water was considered one of the four basic "elements" (earth, wind, and fire as the others) in the universe. With the discovery of more basic constituents, the ter

Kinetic energy, How might temperature changes in the human body have an imp...

How might temperature changes in the human body have an impact on human health

Calculate the flow rate of nitrogen, 1. The feed to an ammonia synthesis re...

1. The feed to an ammonia synthesis reactor is 25% (lbmole) nitrogen with the balance hydrogen. The flow rate is 3000 kg/h at 65°C and 95 bar.  Calculate the flow rate of nitrogen

De-broglie wavelength associated with a particle of mass, The de-Broglie wa...

The de-Broglie wavelength associated with a particle of mass  10 -6 kg moving with a velocity of 10 ms -1 , is: (1) 6.63 x 10 -22 m                (2) 6.63 x 10 -29 m

Cement refactories, what is the effect of cement refactory on wear and tear...

what is the effect of cement refactory on wear and tear

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd