Chemistry Brooks

ORBITALS: (Each Sub-Level adds two Orbitals)

S __

P __  __  __

D __  __  __  __  __ 

F __  __  __  __  __ __  __ 

Optimal Number of Electrons in Each Orbital

S: 2

P: 6

D: 10

F: 14

Today we took notes on Orbital Diagrams. I would have posted my notes but I'm pretty sure that Andrew packed them up with his notes today. I will get them on Monday and post them. But for now here are some notes. HOMEWORK: Remember to finish the above worksheet. ALSO Students should have picked up the extra credit today after school from myself or Mr. Brooks. The worksheet they picked up should be turned in before school on Monday. ALSO REMEMBER THE other extra credit assignment. See previous post. 

NOTES:

http://crescentok.com/staff/jaskew/ISR/chemistry/class4.htm

1. Electron configuration

An electron configuration consists of the symbol for the occupied subshell with a superscript indicating the number of electrons in the subshell.
The electron configuration for sodium (atomic number 11) is


1s²2s²2p⁶3s¹

• The large numbers represent the energy level.
   
• The letters represent the sublevel.
   
• The superscript numbers indicate the number of electrons in the sublevel.

NOTE: Electron configuration can be read directly from the periodic table. On the table outline at the right, helium has been moved into thes-block next to hydrogen, (because its 2 electrons are in the 1sorbital). Each square on the table represents an electron. The shape of the table identifies the subshells (the s, p, d, and f blocks) and each horizontal row represents a given value for n.
The square representing sodium has been colored in on the table above. Click on the table to see how counting the squares will give sodium's electron configuration.
There are two ways to check an electron configuration:

• The last notation in the electron configuration represents the location of the element on the periodic table.Example: the 3s¹ in the electron configuration for sodium above indicates its location as the first square in the s sublevel on the third row of the periodic table.
  
• The total of the superscripts in an electron configuration equals the atomic number of the element.Example: the total of the superscripts in the electron configuration for sodium above is 11, its atomic number.
  
  
  2. Orbital diagram
  An orbital diagram consists of a box representing each orbital and a half arrow representing each electron.
  The orbital diagram below is for sodium (atomic number 11)
  A half arrow pointing up, , represents an electron with m_s = + ¹/₂
  A half arrow pointing down,, represents an electron with m_s = −¹/₂
  The spin of an electron is often referred to as either "spin up" or "spin down".
  NOTE: Orbital diagrams can be read directly from the periodic table as well as electron configurations.
  Electrons are said to be paired when they are in the same orbital. An unpaired electron is one not accompanied by a partner of opposite spin.
  Hund's rule states that for degenerate orbitals, the lowest energy is attained when the number of electrons with the same spin is maximized.
  

  Simply stated - electrons will occupy orbitals singly, if possible, and single electrons in the same subshell will all have the same spin.

  The orbital diagram below represents nitrogen, with unpaired 2p electrons
  Electrons arranged in this way are said to have parallel spins.
  Hund's rule is based in part on the fact that electrons repel one another. By occupying different orbitals, the electrons remain as far as possible from one another, minimizing electron-electron repulsions.
  
  Condensed Configurations
  For large atoms, showing all the electrons with an electron configuration or orbital diagram can become quite complex. Since it is the outermost electrons that are largely responsible for chemical behavior, we can condense the electron configuration and orbital diagram to focus on those electrons.
  

  Outer-shell electrons, those involved in chemical bonding, are called valence electrons. Those electrons below the outer shell, inner-shell electrons, are usually referred to as core electrons.

  The electron configuration and orbital diagram can be condensed by beginning with the nearest (before the atom) noble gas symbol in brackets to represent the core electrons, then showing the valence electrons as usual.Sodium's complete electron configuration is
  1s²2s²2p⁶3s¹The same electron configuration in condensed form becomes
  [Ne]3s¹The complete orbital diagram for sodium is
  The same orbital diagram in condensed form becomes
   

PRACTICE: 

http://glencoe.mcgraw-hill.com/sites/007874637x/student_view0/chapter5/concepts_in_motion.html#