Transcript 3-Atomic models

Atomic Models
Dalton Model
“Billiard Ball” model
1. All matter is made up of tiny indivisible particles called
atoms .
2. All atoms of the same element are the same in size, mass,
etc.
3. Atoms of different elements are different in size and
mass.
4. Atoms of different elements combine in small whole
number ratios to form molecules or compounds.
5. In chemical reactions, atoms are not created or
destroyed. They are rearranged or recombined.
Thomson Model
“Raisin Bun” Model
1. the atom is a spherical cloud of positive
charge with negatively charged electrons
embedded in it.
2. the amount of positive charge equals the
amount of negative charge, so the entire atom
is neutral.
Rutherford Model
“Solar system Model”
1. discovered using the gold foil experiment.
2. the atom is mostly empty space.
3. most of the mass is concentrated in a small,
dense nucleus .
4. electrons move around the nucleus like
planets around the sun .
Bohr Model - Energy Level Model
1. electrons travel around the nucleus in specific
energy levels .
2. if an atom is excited, electrons absorb a
certain amount of energy and are boosted to a
higher energy level.
3. electrons later drop back to a lower state
releasing energy of a colour equal to the
amount of energy released.
4. the first energy levels can hold a maximum of
2 electrons. The others have a valence shell
of 8 electrons.
Emission Spectrum
FROM BOHR TO
SCHROEDINGER
Bohr Model Deficiencies
• Predicts line spectra results that
deviate from the observed as the
Atomic Number increases.
• Fails to maintain consistency with
observed periodic structural trends in
valence level and valence electrons
beyond Atomic Number 18.
• Equates position with energy and
does not allow Potential and
Kinetic Energy inter-conversion.
• Fails to account for how electrons
make energy (orbit) transitions if
they are not permitted to be at any
distance but the allowed orbit
distance.