3. Compounds are the combination of
atoms with a specific ratio.
4.Chemical reactions involve
reorganization of the atoms.
Thomson's atomic model
Raisin in the plum pudding
Experiment with cathode
ray and conclude that
matters consist of
negatively charged particle
called electron.
Calculate mass/charge ratio of electron = -5.686 * 10^12 kg/C
Rutherford's atomic model
Suggest the atomic nuclear model from the results
of bombardment gold foil with alpha particles.
Atom consists of electrons which move around the
positively charged center called nucleus.
atomic planetary model
Atom is mostly empty space. The size of nucleus is
very small compare to the atom itself.
Quantum View of Atom
Bohr's model
Bohr proposed that atom has energy levels as circular
orbits. Electrons move as wave in a specific energy
levels. Electrons can transfer to different energy levels
when they lose or gain energy.
Each energy level has specific
quantum number (n) starts from
1,2,3...
Erwin Schrödinger used Quantum Mechanics
to explain the energy state in the hydrogen
atom.
The equation is called wave
function. A specific wave function is
often called an orbital.
Quantum number and atomic orbitals
the principal quantum number (n)
n = 1,2,3... small n, small size, close to nucleus,
low energy
the orbital angular momentum quantum
number (l)
give different shape of orbital
s p d f orbitals
the magnetic quantum number (ml)
give different orientation of orbital
the spin quantum number (ms)
represent spin of electron. Only two possible values : +1/2 and -1/2
Wave Particle Duality
In subatomic level, energy and matter cannot be distinguished.
They have both light and particle properties.
light consists of particles called
photon. Photon travels as wave.
Matter consists of atom and
subatomic particles. Subatomic
particles such as electrons travel or
move as wave.