Download Atomic Structure - Chemistry-MYP

Atomic Structure
Cathode Ray and Electrons
Rutherford and the Nucleus
• Ancient Greek Philosopher (460-370 BC)
• “Father of modern science”
• Theorized that everything was composed
of “atoms” which are indivisible and
indestructible.
• There are an infinite number of atoms and
kinds of atoms.
• French chemistry; 1743-1794
• Transformed chemistry from qualitative to
quantitative.
• Helped construct the metric system.
• Proved the conservation of mass,
replacing current theory with fact.
• Guillotined during French Revolution.
• English chemist; 1766-1844
• Elements are made of extremely small particles
called atoms.
• Atoms of a given element are identical in size,
mass, and other properties; atoms of different
elements differ in size, mass, and other properties.
• Atoms cannot be subdivided, created, or
destroyed.
• Atoms of different elements combine in simple
whole-number ratios to form chemical compounds.
• In chemical reactions, atoms are combined,
separated, or rearranged.
J.J. Thomson
• British physicist; 1856-1940
• Credited with discovery of the electron.
• Used Cathode Ray Tubes (CRT) to show
electron beam or cathode ray.
• Invented the mass spectrometer.
Cathode Ray Tube Experiment1
• The electrometer
verified that the
charge on the stream
of particles was
negative.
Cathode Ray Tube Experiment2
• The ‘rays’ can be
deflected with
both a magnetic
and electrical
field.
Thomson Atomic Model
• Thomson put forth
the ‘plum pudding’
model.
• Electrons were
scattered
throughout a
positive sphere.
Ernest Rutherford
• New Zealand Physicist; 1791-1867
• Credited with discovery of the nucleus and
the proton.
• Proved transmutation during radioactive
decay.
• First to split an atom.
• Famous Gold Foil Experiment.
Ernest Rutherford, Hans Geiger,
Ernest Marsden
Rutherford’s view of an atom.
R.G.F Experimental Conclusions
• Rejected JJ Thomson’s Plum Pudding
Model.
• Small positively charged center,
nucleus.
• Electrons surround the center in a
cloud.
• The atom is mostly empty space.
Robert Millikan
• American Physicist; 1868-1953
• Credited with finding the electronic charge
on a single electron.
• Famous oil drop experiment.
• Proved existence of cosmic radiation.
Oil Drop Experiment
James Chadwick
• British Physicist; 1891-1974
• Credited with the discovery of the neutron
and its mass while working with
Rutherford.
• Worked on the Manhattan Project.
• Studied radiation under Hans Geiger.
Niels Bohr
• Danish Physicist; 1885-1962
• Developed the orbital model of electron
movement around the nucleus.
• Developed quantum mechanics – the
theory that electrons move between
energy levels in discrete steps.
• Proved that light can act like a wave and a
particle.
• Worked on the Manhattan Project.