The Atom
Atomic States
• An atom can be in one of two states:
1. Ground State: When an atom has the lowest
possible amount of energy.
2. Excited State: When an atom has excess energy.
Excited vs. Ground State
• An atom without energy begins at ground state.
• When an atom absorbs energy from an outside
source, it enters an excited state.
• When an atom
emits a photon of
light, it returns
back to it’s ground
state.
Energy Level Diagram
• Energy in the photon that is emitted
corresponds to the energy used by the atom
to get to the excited state.
The Hydrogen Atom
• Only certain types of photons are produced
when Hydrogen atoms release energy.
• This is because only certain energy changes
are occurring. Hydrogen has certain discrete
energy levels.
The Hydrogen Atom
• If a hydrogen atom emits a red photon, it has
released a small amount of energy.
• If a hydrogen atom
emits a blue photon,
it has released a
larger amount of
energy.
The Hydrogen Atom
• Each photon (or packet of light energy)
corresponds to a particular energy change in
the hydrogen atom.
• From this diagram, one
can see the 4 discrete
energy levels of Hydrogen
that correspond to the 4
colors of visible light
emitted.
The Wave Mechanical Model
• Scientists knew that the Bohr model was
incorrect. They needed a better model.
• The Wave Mechanical Model described the
atomic states by using
ORBITALS.
• Orbitals are NOT like orbits.
The Wave Mechanical Model
• The Wave Mechanical Model, using the orbital,
suggests there is the highest probability of
finding the electron at any particular moment
near the center of the atom. You can’t be sure
the electron will be near the center of the atom,
but it probably will.
• The electron’s path cannot be precisely
described, only a prediction of it’s probability.
• The model gives NO information about when the
electron occupies a certain point in space or how
it moves.
The Hydrogen Orbitals
• We have already discussed that the Hydrogen
atom has 4 discrete energy
levels.
• These are called “Principal
Energy Levels”
• These energy levels are
labeled with whole numbers
The Hydrogen Energy Levels
• The energy levels are then further divided into
sublevels.
• Principal Energy Level 1, consists of one
sublevel: 1s.
• Principal Energy Level 2,
consists of two sublevels:
2s and 2p.
The Hydrogen Energy Levels
• Principal Energy Level 3, consists of three
sublevels: 3s, 3p, and 3d.
• Principal Energy Level 4, consists of four
sublevels:
4s, 4p, 4d, and 4f.
Energy Levels & Orbitals
• These sublevels contain spaces for the
electron that we call orbitals.
• Principal energy level 1 consists of just one
sublevel or one type of orbital.
• This orbital is spherical in shape.
• We label this orbital 1s.
• The number 1 is for the principal energy level.
• The s labels the particular sublevel.
Energy Levels & Orbitals
• Principal Energy Level 2 has 2 sublevels: 2s & 2p.
• The 2s sublevel consists of one orbital: 2s.
• The 2p sublevel consists of three orbitals: 2px,
2py, 2pz.
Orbitals
• Different orbitals have different shapes.
• The s orbital is always a sphere. It can hold 2
electrons.
• The p orbital has 2 lobes. Each set of lobes: x,
y, & z can hold 2 electrons, so the p orbital can
hold a total of 6 electrons.
• The d and f orbitals
have other shapes.