the quantum model of the atom Chapter 4 section 2 the quantum model of the atom

Electrons as waves Bohr’s atomic model explained electron behavior very well in gasses but his model did not work to explain electron behavior in all atoms. Because of the photoelectric effect and the line spectrum of hydrogen, light has a dual wave/particle nature Electrons are thought to behave the same way

Electrons as waves Louis de Broglie, a French scientist, proposed that electrons could have the same dual wave/particle nature. Sometimes the electron has wavelike properties and sometimes it has particle properties.

Electrons as waves De Broglie suggested the electrons be considered waves confined to the space around the nucleus.

Electrons as waves De Broglie and others confirmed through experiments that electrons can be bent(diffracted) and can experience interference.

Heisenberg uncertainty principle Werner Heisenberg, german, theoretical physicist Questioned electrons as waves and particles. If this was true, where are the electrons located in the atom?

Heisenberg uncertainty principle Heisenberg uncertainty principle - proposed that it is impossible to determine simultaneously both the position and velocity of an electron Because of this it has been proven to be one of the fundamental principles of our understanding of light and matter

Because of schrodinger, Heisenberg, and de Broglie and other scientists Electrons are now thought to be in regions, not specific orbits. These regions are called orbitals Orbitals are three dimensional regions around the nucleus that indicate the probable location of an electron

orbitals There are 4 orbital shapes S p d f

S orbitals

P orbitals

D orbitals

F orbitals

S orbitals Sphere shape Maximum of 2 electrons in each shape

P orbitals Dumbbell shape Maximum number of electrons in each shape – 2 Total electrons in the p orbitals – 6

D orbitals Maximum number of electrons each shape – 2 Total number of electrons for the d orbitals - 10

F orbitals Maximum number of electrons per shape – 2 Total number of electrons for f orbitals - 14

Orbital blocks on periodic table

We can use the periodic table to help us find the electron locations in elements atoms

Quantum numbers specify the properties of atomic orbitals and the properties of electrons in orbitals. Principal quantum number Angular momentum quantum number Magnetic quantum number Spin quantum number

Principal quantum number Symbol – lower case n Indicates the main energy level of the electrons N=1 1st energy level n=4 n=7 N=2 2nd energy level n=5 N=3 3rd energy level n=6

Angular momentum quantum number Symbol – lower case l Indicates the shape of the orbital L=0 s shape L=1 p shape L= 2 d shape L= 3 f shape

Magnetic quantum number Symbol – lower case m Indicates the orientation of an orbital around the nucleus M = 0 s orbital M= -1, 0, +1 p orbital M = -2, -1, 0, +1, +2 d orbital M = -3,-2,-1,0,+1,+2,+3 f orbtial

Spin quantum number Symbol is 1 2 or - 1 2 Indicates the two spins of electrons, positive or negative