Electron Configuration

Textbook Connection Chapter 4 The Development of a New Atomic Model Light has characteristics of both particles and waves Photoelectric Effect Energy Levels Bohr Model The Quantum Model of the Atom Electrons as Waves Heisenberg’s Uncertainty Principle Orbital Probabilities Quantum Numbers Electron Configurations Aufbau Principle Electron Configuration Forms

Textbook Connection Homework – Due November 7th Page 104 – 1, 2, & 3 Homework – Due Nov. 10th Page 116 – 1, 2, 3, 4, & 5

First, A Little Review: Electrons are just one of the three major components of Atoms. The Electron’s mass is so small in comparison to the other subatomic particles that its mass can be ignored in most cases. Electrons have a charge that is equal but opposite (negative) to that of the Proton (+)

Review continued… The electron was the first subatomic particle to be discovered (J. J. Thomson) http://dbhs.wvusd.k12.ca.us/webdocs/AtomicStructure/Disc-of-Electron-Images.html

Review Continued… Ernest Rutherford’s “Gold Foil” experiments showed that the atom is mostly empty space with relatively great distances between the electrons and the nucleus.

Rutherford Model Electrons existed in set orbits around the nucleus. Problems with this model is that electrons would fall into the nucleus almost instantly. http://www.es.flinders.edu.au/~mattom/science+society/lectures/illustrations/lecture28/rutherford.html

Modern Atomic Theory Max Planck – “ Energy is not continuous.” While studying the radiation of heated materials, he attempted to make connections to the radiating atom. Based on his observations, he determined that energy is always emitted or absorbed in discrete units which he called “quanta.” Energy = frequency of the radiation * constant This constant is known as Planck’s constant and is equal to 6.63 x 10-34 J * s

http://coocooforclocksblog.com/wp-content/uploads/2011/11/strike-when-the-iron-is-hot.jpg

Albert Einstein – Photoelectric Effect Applied Planck’s work further to the idea such that light energy should be explained as “packets” of energy (quanta) which he called “photons” that could be seen to behave as both wave and particle. This idea lead to an understanding of why metals lose electrons when they absorb electromagnetic radiation. http://hyperphysics.phy-astr.gsu.edu/hbase/imgmod2/pelec.gif

Niels Bohr– Refined Rutherford atomic model to explain how electrons resist “falling” into the nucleus. Electrons can only exist in discrete levels or “orbitals” at some distance away from the nucleus based on the amount of energy the electron has. Electrons can move between levels only if they absorb or radiate a set amount of energy (quanta)

Louis de Broglie – Particle/wave duality Discovered that electrons had a dual nature – similar to both particles and waves which supported Einstein’s concepts of matter and energy. http://www.youtube.com/watch?v=JIGI-eXK0tg

Heisenberg – Uncertainty Principle Continued to build on the principles of de Broglie and developed formulas connected to the frequencies of spectral lines. “It is impossible to know both the location and velocity of an electron.”

Schrodinger – Mathematical model of quantum mechanics Viewed electrons as continuous clouds and developed mathematical probabilities of electrons’ existence in the atom. Schrodinger’s Cat – All explanations of the realities related to a specific situation remain valid until the “box” is opened.

James Chadwick – Isolates the Neutron Using alpha particles he discovers and isolates the neutral atomic particle with a mass close to a proton. http://sccscience.files.wordpress.com/2009/02/atom_nucleon.jpg

Bohr Model Neils Bohr proposed a model that had electrons existing in orbitals around the nucleus that were differentiated by the amount of energy that they had. http://www.answers.com/topic/bohr-planetary-atom-model-jpg

Quantum Model The Quantum Model proposed by Schrodinger’s equations, De Broglie’s wave/particle theory, and Heisenberg’s Uncertainty Principle gives us a much more complex view of the organization of the electron’s of atoms.

Quantum Mechanical Model Unlike the Bohr model, the Quantum model does not restrict an electron to an exact path but instead estimates a probability of finding en electron in a certain position. Similar to Bohr, electrons finding themselves in predicted areas called “Orbitals” based on having a set amount of energy.

Atomic Orbitals Orbitals are organized by a number of different factors (Quantum Numbers): Principle Energy Level Refers to the energy Level, (relative ‘distance’) from the nucleus. Currently, n = 1 – 7 Atomic Orbitals (l angular momentum) Letters denote the estimated “shape” of the orbital

“S” - Orbital 1 orbital “space” = maximum 2 e-

Orbitals are organized by a number of different factors (Quantum Numbers): Magnetic Quantum Number Tells us the orientation of the space (X, Y, or Z) Spin Quantum Number Electrons cannot occupy the same space at the same time so +1/2 or -1/2 to indicate the direction of movement

3 orbital “spaces” = maximum 6 e- “P” - Orbitals 3 orbital “spaces” = maximum 6 e-

5 orbital “spaces” = maximum 10 e- “D” - Orbitals 5 orbital “spaces” = maximum 10 e-

7 orbital “spaces” = maximum 14 e- “F” - Orbitals                                                                                                                          7 orbital “spaces” = maximum 14 e-

Sublevels The number of sublevels is always equal to the principle energy level n = 1  1 sublevel n = 2  2 sublevels n = 3  3 sublevels n = 4  4 sublevels n = 5  5 sublevels The maximum number of electrons that can be found on any energy level can found using the equation “2n2” Energy level “3”  n = 3  2(3) 2 = 18 maximum electrons

Pattern of Electron Configuration Start 1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 5g 6s 6p 6d 6f 6g 6h 7s 7p 7d 7f 7g 7h 7i

Electron Configuration Examples Start 11 Na 22.989 1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 6s 6p 6d 6f 7s 7p 7d 7f 1s2 2s2 2p6 3s1 7 e- - 6 e- = 1 e- 9 e- - 2 e- = 7 e- 11 e- - 2 e- = 9 e-

Another Example: Start Co 1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 27 Co 1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 6s 6p 6d 6f 7s 7p 7d 7f 1s2 2s2 2p6 3s2 3p6 4s2 3d7 27 e- - 2 e- = 25 e- 9 e- - 2 e- = 7 e- 25 e- - 2 e- = 23 e- 23 e- - 6 e- = 17 e- 17 e- - 2 e- = 15 e- 15 e- - 6 e- = 9 e-

Now Try These: 12Mg 18Ar 1s2 2s2 2p6 3s2 35Br 1s2 2s2 2p6 3s2 3p6 82Pb 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p5 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p2