Put the Historical Perspectives Reading Assignment on your table Clear off everything except for a pencil, calculator (no cell phones), and periodic table When finished the quiz, fill out BINGa sheet with elements 1-36

Announcements Half of Thursday’s class will be spent in the library – independent study of the periodic table Quiz #2 – Wed Feb. 22 Unit test – Mon Feb. 27

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. Minced meat 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 D. Vietnamese beef noodles stuffed inside a Chinese wonton 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

More About Shells Shell 4 3 2 1

More About Shells Shell 4 3 2 1 1s22s22p63s23p64s23d104p6 2 8 8 18

1s 1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 5d 6p 6d 7s 4f 5f

How did you figure out the rest of the labels How did you figure out the rest of the labels? What do the labels represent? The labels represent the last subshell to be filled. Every element space represents 1 electron. Compare your labeled periodic table with the orbital energy level diagram. What do you notice? The energy levels of the subshells correspond with the labels on the periodic table

Ar: 1s2 2s2 2p6 3s2 3p6 3p5 3p3 3p1 3p2 3p4

Ga: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p1

Rn: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6

Aufbau

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

Core Notation Example: Write the electron configuration for Ga using core notation. Closest previous noble gas element: ______ Remaining configuration: _____________ Core notation: Ar 4s23d104p1 [Ar] 4s23d104p1

[Ar] 4s2 3d 5

Exceptions There are 2 exceptions Cr and Cu

What you would expect for Cr

In Reality

What you would expect for Cu

In Reality

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

Know the electron configuration for Cr and Cu!

Valence Electrons 1s2 2s22p6 3s23p6 4s1 When atoms undergo a chemical reaction, only the outermost e- are involved (furthest from nucleus and highest in energy  valence electrons

Electron Configuration Valence Electrons Valence electrons are the ones in the s and p subshells beyond the noble gas core, and any partially filled d and f subshells Atom Electron Configuration # Valence e- Al Ga Pb Xe [Ne] 3s23p1 3 [Ar] 4s23d104p1 3 [Xe] 6s24f105d106p2 4 [Kr] 5s24d105d6

Valence Electrons Can you see a pattern for counting valence electrons on the periodic table?

Valence Electrons Can you see a pattern for counting valence electrons on the periodic table? # of valence e- down a group stays the same # of valence e- of groups 1-2 are 1 and 2 # of valence e- of groups 13-17 are 3-7

O: 1s22s22p4 O2-: ?? Negative Ions What’s changed from O to O2-? If you had to guess where to stick the two electrons, where would they go? O2-: ??

Negative Ions 1s22s22p4 + 2e-  1s22s22p6 Ne Ar 1s22s22p63s23p4 + 2e- Add the extra electron(s) where you left off in the neutral atom Example: Write the electron configuration for the following negative ions: a) O2- 1s22s22p4 + 2e-  1s22s22p6 Ne b) S2- Ar 1s22s22p63s23p4 + 2e-  1s22s22p63s23p6 c) Br- Kr [Ar]4s23d104p5 + 1e-  [Ar]4s23d104p6

Negative Ions Note that negative ions have the same electronic configuration as the nearest noble gas on the periodic table  isoelectronic

Negative Ions

Negative Ions Note that negative ions have the same electronic configuration as the nearest noble gas on the periodic table  isoelectronic If two atoms have the same electronic configuration, are they the same element? NO!!! Remember that it is the #p that determines the element.

Positive Ions Sn: Sn2+: ?? 1s22s22p63s23p64s23d104p65s24d105p2 What has changed between Sn and Sn2+? Before I ask you if you had to guess where the electrons will be removed from, where are they most definitely not removed from? Which subshells are not involved in creating a positive ion?

Positive Ions [Kr]5s24d105p2 - 2e-  [Kr]5s24d10 [Kr]5s24d105p2 - 4e- Electrons in subshells with the highest n value and highest energy are removed first Electrons are removed from the p-subshell before the s and d Example: Write the electron configuration for the following positive ions: a) Sn2+ [Kr]5s24d105p2 - 2e-  [Kr]5s24d10 b) Sn4+ [Kr]5s24d105p2 - 4e-  [Kr]4d10 c) V2+ [Ar]4s23d3 - 2e-  [Ar]3d3

Let’s play BINGa!!!!!