Recap What does “ground state” refer to? A. A hydrogen atom B. Lowest energy state of an atom C. Highest energy state of an atom D. When the atom is on the ground B. Lowest energy state of an atom
Recap How does an electron become “excited?” A. The atom it resides in reacts with another atom B. It absorbs energy and jumps shells C. It absorbs specific amounts of energy and jumps shells D. When it sees a particle of opposite charge C. It absorbs specific amounts of energy and jumps shells
Recap What is a photon? A. A packet of light B. An excited proton C. An excited electron A Chinese wonton stuffed with Vietnamese noodles A. A packet of light
White Light Spectrum Emission Spectrum of H
Recap What is an orbital? A. The path an electron takes around the nucleus B. Lobes C. The shape of the nucleus D. Mathematical description (probability) of where to find an electron in an atom D. Mathematical description (probability) of where to find an electron in an atom
Electron Configuration Where are the electrons?
Energy Level Diagram Shell 4 3 orbitals 2 subshells 1
Rules to follow when filling orbitals: Fill orbitals from lowest to highest energy (Aufbau Principle) Place one electron in each orbital of a sub-shell When each orbital of a sub-shell has one electron, go back and pair the electrons (Hund’s Rule) If two electrons are in a orbital, they must have opposite spin (Pauli Exclusion Principle)
electron-electron repulsion These rules ensure that the electron configuration gives the ___________ energy, most __________ atom by reducing ________________________________. lowest stable electron-electron repulsion
More About Shells Shell 4 3 2 1 1s22s22p63s23p64s23d104p6 2 8 8 18
How can you write the electron configuration without the energy level diagram???
Aufbau
1s 1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 5d 6p 6d 7s 4f 5f
Ar: 1s2 2s2 2p6 3s2 3p6 3p5 3p3 3p1 3p2 3p4
Ga: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p1
Ag: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d9
Rn: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6
K [Ar] 1s2 2s2 2p6 3s2 3p6 4s1 1s2 2s2 2p6 3s2 3p6 Ti [Ar] 4s2 3d2 1s2 2s2 2p6 3s2 3p6 Ni [Ar] 4s2 3d8 1s2 2s2 2p6 3s2 3p6 Ga [Ar] 4s2 3d10 4p1 1s2 2s2 2p6 3s2 3p6 Kr [Ar] 4s2 3d10 4p6 Ar
[Ar] 4s2 3d 5
Example: Write the electron configuration for Ga using core notation. Closest previous noble gas element: ______ Core notation:___________________ Ar [Ar] 4s23d104p1
Practice: Write the electron configuration for the following elements. Zn _______________________________ K ________________________________ Kr _______________________________
There are 2 exceptions to the electron configuration of elements up to Kr:
What you would expect for Cr
In Reality
What you would expect for Cu
In Reality
Reason: ½ filled and completely filled subshells are more stable than partially filled subshells, and in Cr and Cu, it only takes one electron to achieve this stability in the 3d subshell Expected Reality Cr [Ar] 4s23d4 [Ar] 4s13d5 Cu [Ar] 4s23d9 [Ar] 4s13d10