Download Atomic Structure

Atomic Structure
Way Early Theories
• Democritus (460-370 BC)
–First person to propose that
matter is not infinitely divisible
–Atomos
–Matter is empty space through
which atomos move
Way Early Theories
•Aristotle (384-322 BC)
–Disagreed with the empty space
idea
–Rejected Democritus’s idea of
atomic theory
–Believed all matter was fire,
earth, air, and water
Early Theories
•John Dalton (1766-1844 AD)
–All matter is made of atoms.
–All atoms of a given element are
identical and are different from atoms of
other elements.
–Atoms cannot be created, destroyed, or
divided into smaller particles.
–Atoms combine in simple whole number
ratios to make compounds.
–In a chemical reaction, atoms are
separated, combined, or rearranged.
Early Theories
•J.J. Thomson (1856-1940 AD)
–Worked with cathode ray tubes
(CRT’s)
–Deduced that the negatively
charged particles flowing through
the CRT were electrons…hence
the first subatomic particle was
discovered
Early Theories
•J.J. Thomson (1856-1940 AD)
–Proposed a model of an atom to
explain the neutrality of an atom
–Plum Pudding Model
Early Theories
Early Theories
•Ernest Rutherford (1871-1937
AD)
–Inadvertently disproved the
Plum Pudding Model
–Fired alpha particles (positively
charged) at gold foil
–Some alpha particles were
deflected at huge angles
Early Theories
•Ernest Rutherford (1871-1937
AD)
–Proposed that the atom had a tiny,
dense central portion
–Electrons move through empty
space around the nucleus
–Later stated that protons were in the
nucleus
Early Theories
•James Chadwick (1891-1974
AD)
–Proposed that the nucleus had
another particle in it with a mass
near that of the proton but with
no charge
Early Theories
•James Chadwick (1891-1974
AD)
–Proposed that the nucleus had
another particle in it with a mass
near that of the proton but with
no charge
Early Theories
•Niels Bohr (1885-1962 AD)
–Proposed a quantum model of
the atom in which the electrons
followed distinct orbits around the
nucleus
–It worked for H.
Early Theories
Current Theory
•Louis de Broglie (1892-1987
AD)
–Proposed that the electrons
traveled in a wave-like orbits
–Known as the Quantum
Mechanical Model
Current Theory