Structure of Atom (Part 3)

Discovery of Proton:

In 1886 Goldstein observed that in addition to cathode rays, other rays were also present in the discharge tube. These rays were traveling in opposite direction to cathode rays. He used a discharge tube having perforated cathode. He found that these rays passed through holes present in the cathode and produced a glow on the walls of the discharge tube. He called these rays as "canal rays".

The properties of these rays were as following:

i. These rays travel in straight lines in a direction opposite to the cathode rays.

ii. Their deflection in electric and magnetic field proved that these are positively charged.

iii. The nature of canal rays depends upon the nature of gas, present in the discharge tube.

iv. These rays do not originate from the anode. In fact these rays are produced when the cathode rays or electrons collide with the residual gas molecules present in the discharge tube and ionize them as follows:

v. Mass of these particles was found equal to that of a proton or simple multiple of it. The mass of a proton is 1840 times more than that of an electron.Thus, these rays are made up of positively charged particles. The mass and charge of these particles depend upon the nature of the gas in the discharge tube. Hence,different gases produce different types of positive rays having particles of different masses and different charges. Keep in mind that positive particles produced by a gas will be of the same type i.e. positive rays produced by the lightest gas hydrogen contain protons.

Comments

Relative Atomic Mass

Hello readers! Hope you will be fine. Our today's topic is relative atomic mass. let's start! It is the average mass of the atoms of that element as compared to1/12th the mass of an atom of carbon-12 isotope. Based on carbon-12 as a standard, the mass of an atom of carbon is 12 units and 1/12th of it comes to be 1 unit. When we compare atomic masses of other elements with atomic masses of carbon-12 atom, they are expressed as relative atomic masses of those elements. The unit of relative atomic mass unit is amu (Atomic mass unit). One atomic mass unit is 1/12th the mass of one atom of carbon-12. This was the short intro of Relative atomic mass. See you next with another topic. Thank you!

Structure of Atom(Part 5)

Rutherford's Atomic Model: Rutherford performed 'Gold Foil' experiment to understand how negative and positive charges could coexist in an atom. He bombarded alpha particles on a 0.00004 cm thick gold foil. Alpha particles are emitted by radioactive elements like radium and polonium. These are actually helium nuclei (He2+). They can penetrate through matter to some extent. He observed the effects of α-particles on a photographic plate or a screen coated with zinc sulphide. He proved that the 'plum-pudding' model of the atom was not correct. Observations made by Rutherford were as follows: i.Almost all the particles passed through the foil un-deflected. ii.Out of 20000 particles, only a few were deflected at fairly large angles and very few bounced back on hitting the gold foil. Results of the experiment: Keeping in view the experiment, Rutherford proposed planetary model for an atom and concluded following results: i.Since most of the particles passed through th

Carbon Cycle

CARBON CYCLE: Carbon circulates through the carbon cycle. It shows that carbon may be pres- ent as gaseous atmospheric CO2 constituting a relatively small but highly significant portion of global carbon. Some of the carbon is dissolved in surface water and groundwater as HCO-3 or molecular CO2 (aq). A very large amount of carbon is present in minerals, particularly magnesium and calcium carbonates such as CaCO3. Photosynthesis fixes inorganic C as biological carbon. represented as (CH2O), which is a constituent of all life molecules. Another fraction of carbon is fixed as petroleum and natural gas, with a much larger amount as hydrocarbonaceous kerogen (the organic matter in oil shale), coal, and lignite. Manufacturing processes are used to convert hydro- carbons to xenobiotic compounds with functional groups containing halogens, oxygen, nitrogen, phosphorus, or sulfur. Although a very small amount of total environmental carbon, these com- pounds are particularly significant because of

Fun with Chemistry

Search This Blog