Micromeritics - Fundamental and Derived Properties of Powders
The theory of atom
1. Rutherford’s Theory
Albert C. (x-10) (1)
Julius C. (x-10) (11)
Nicholas S. W. (x-10) (17)
Sinclair K. (x-10) (19)
2. background
• Born in brightwater, New Zealand
30 August 1871
• Son of James Rutherford and Martha
Thompson
• Student of J.J. Thomson
• Take school in new zealand (M.A.)(master of arts),
canada (B.A.)(bachelor of arts) and england
(Professor of Physics)
3. His research
• Alpha “rays” / particles
• Theory of protons
• Detector for electromagnetic waves
4. In 1899, Rutherford had discovered alpha "rays"
from uranium. Now, today we know they are not
rays, they are particles; alpha is a nucleus of
helium.
5. What are alpha rays / particles?
• High speed particles
• Made up of two protons and two neutrons
• Is a nucleus, same as the nucleus of a
common atom of helium
• Don’t have electrons around it
• Type of ionizing radiation
• will loose all their energy in just a couple
inches of travel in air
6.
7.
8. A uniform layer of powered uranium compound was spread on
plate A and the rays allowed to ionize the gas between plates A
and B. The amount of ionization is measured by the "saturation
current" received at B when the potential difference between A
and B is great enough to pull all the ions to the plates before
they are able to recombine. Rutherford then proceeded to
cover the uranium with aluminum sheets of various thicknesses
and measure the current, using the electrometer. Rutherford
was in the process of checking to see if this was true or not,
because Becquerel had also made other claims about uranium
radiation which turned out to be incorrect. Now, what
Rutherford did find was that there were at least two different
"rays" being emitted by the uranium and he called them α and
β.
9. What are alpha rays?
Alpha "rays" are actually high speed particles. An alpha
particles is made up of two protons and two nneutrons,
all held together by the same strong nuclear force that
binds the nucleus of any atom. In fact, an alpha particle
really is a nucleus - it's the same as the nucleus of a
common atom of helium - but it doesn't have
any electrons around it, and it's traveling very fast.
Alpha particles are a type of ionizing radiation. but
Alpha particles will loose all their energy in just a
couple inches of travel in air. Once an alpha particle is
stopped, it grabs the first two free electrons it can find,
and becomes a plain old atom of helium.
