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

Assignment, solution and collegative properties explanation

solution and collegative properties explanation

Explain pre and primary processing -some basic concepts, Pre And Primary Pr...

Pre And Primary Processing -Some Basic Concepts In the earlier three units, we learnt about the principles and methods of food processing. Certain issues related to production,

Sodium, The extraction of sodium metal

The extraction of sodium metal

What is the mass of the tube, A covered glass tube contains 2.25g of copper...

A covered glass tube contains 2.25g of copper and 3.32g of sulphur. The mass of the tube as well as its contents is 18.48 g. Upon heating a chemical reaction forms copper(II) sulph

Explain about the intrinsic breakdown, Explain about the Intrinsic breakdow...

Explain about the Intrinsic breakdown: It's because of the excitation of electrons into the conduction band across  the  energy  gap  under  the  condition  of  excessive  volt

The correct sets of the four quantum numbers 4d electron, Which of the fol...

Which of the following represents the correct sets of the four quantum numbers of a 4d  electron: (1)  4,3,2,1/2                        (2) 4, 2, 1, 0 (3)  4,3,-2+1/2

Clch2ch2ch2coph +koh+meoh -> the product is...?, ClCH 2 CH 2 CH 2 COPh + Me...

ClCH 2 CH 2 CH 2 COPh + Methanoic acid ---------------->   CH2-(CH2)-CH2-CO-C 6 H 6

Describing inorganic compounds, It is important to differentiate the stoich...

It is important to differentiate the stoichiometric or empirical formula of a molecular substance from its molecular formula. The former expresses only the relative numbers of atom

O-hydroxy benzoic acid , o-isomer is more volatile and how separated by ste...

o-isomer is more volatile and how separated by steam distillation?

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