Name ____________________________________
Period ____________
10-1 Line Spectrum & the Bohr Model
1) Bore model of the atom
a) Rutherford’s gold foil experiment proved that an atoms electrons
must be outside the nucleus and rotating randomly
b) A few years later Bohr started examining the light elements emit
when they become electrically charged.
i) Bohr realized that elements always emit the same colors of
light when an electric current is passed through them .
(1) Line Spectra- The colors of light emitted by elements when
energy is applied to them
(a) When the line spectrum was put through a prism it was
found that each color a element emits is a mix of many colors of light
ii) Bohr knew that if electrons rotated around a nucleus of an atom randomly as Rutherford
suggested they would not be able to form such predictable
or line spectra.
patterns of light
1) Bohr Model of the atom
a) In order to explain how elements produce line spectra Bohr said that electrons must rotate around the
nucleus at constant distances like planets around the sun
i)
Energy levels – the distances that electrons can rotate away from the nucleus
(1) Bohr labeled each energy level with a quantum number (n).
ii) Bohr said that all light (including elements line spectrum) must comes from an atoms electrons
(1) When an atoms electrons absorb energy they jump from energy levels closer to the nucleus of
an atom (n=1) to energy levels farther from the nucleus of an atom (n=2)
(2) When electrons fall back to their usual distance away from the nucleus they release that
energy in the form of light.
(a) The farther the electron falls the more energy the light has.
10-3 The Quantum Mechanical Model of the Atom
1) The Quantum Mechanical model of an atom
a) Werner Heisenberg realized a flaw in Bohr’s model saying that you cant know a electrons speed
and position at the same time
b) Heisenberg uncertainty principal – You can never know a particles exact speed and
position
(1) By describing electrons around an atom according to where they are most often instead of where
they always are you can make Bohr’s model of the atom fit all of Heisenberg’s new ideas
1) Quantum numbers describe the general location of a electron in the
quantum model of an atom
a) Quantum Numbers – a series of numbers and symbol
that represent where an electron is
on an atom
i) Quantum numbers start general and get more
specific as they go on
(1) Principle Quantum Number- how far an
electron is from the nucleolus
(a) n=1 , n=2
(2) Sublevel– the 3/d shape that the
electron ascribes as it rotates is in
(a) S, p, d, or f
(3) Orbital the places within the shape where electron are usually fond
(i) s-sublevel has 1orbital
(ii) p-sublevel has 3 orbitals
(iii)d-sublevel has 5 orbitals
(iv) f-sublevel has 7 orbitals
(b) There can only be 2 electrons per orbital
(4) Spin (up or down) – In order to differenceate 2 electrons that occupy the same energy level (n),
Sublevel (l), and orbital (m), chemists say that one electron in that orbital spins up, and the other
spins down
4-4 Orbital Filling
1) There are three ways to write where electrons are in an atom, an electron configuration, an orbital box
diagram, and valance dot structure.
a) An electron configuration- is a shorthand notation for indicating the number of
electrons in each sublevel.
The notation can be broken down as shown below:
(I) The Aufbau principal - An electron will always occupy the lowest energy
orbital available to it.
(i) You would fill the 4s sublevel before the 3d sublevel because the 4s sublevel is actually
lower in energy
The electron configuration for Helium:
Helium has 2 electrons both in the s sublevel of energy level :
number of electrons in the sublevel
principle energy level
1s2
sublevel (shape of orbital)
The electron configuration for Li would be:
The periodic table shows the Aufbau principal
b) An orbital box diagram- uses boxes to represent orbitals and arrows to represent
electrons.
(I) Each box represents electron orbital’s
(i) There can only be 2 electrons in each box
 Electrons in each box must spin in opposite directions
(ii) s sublevel gets 1 box
(iii)p sublevel gets 3 boxes
(iv) d sublevel gets 5 boxes
(v) f sublevel gets 7 boxes
The orbital box diagram for Helium:
x
He =
z
    
1s
The orbital box diagram for Mg would be:
y
2s
2p
(II) Electron dot diagram – represents only the outermost or valance electrons as
dots
(i) Valance energy level – outermost principal energy level


There can be a maximum of eight valance electrons and they will be
found in the outermost s and p orbitals
Dot electrons going either clockwise or counter clockwise, and only pair up electrons
after there 4, (1 on every side)
Electron dot diagram for He:
He
The electron dot diagram for P would be:
A) What are the rules for putting the electron within an orbitals:
1) The rules for deciding where the electrons are in an atom are:
16
8
Electron Configuration
O
Orbital Box Diagram
Electron-dot Diagram
35
17
Electron Configuration
Cl
Orbital Box Diagram
Electron-dot Diagram
127
52
Electron Configuration
Te
Orbital Box Diagram
Electron-dot Diagram