2.06 Electron Configuration Parts I and II

Part I: Bohr Model of the Atom How are electrons arranged in an atom? Bohr: Electrons in definite energy levels around the nucleus Explained Hydrogen but not comprehensive enough for other elements

Modern Theory for Electrons Modern Theory (also called the Quantum Mechanical Model or Electron Cloud Model): Electrons move in a “beehive” around the nucleus in a “cloud” of energy An _________ is a region of space where an electron is likely to be found

Shapes Different types of orbitals have sublevel shapes depending on how much energy there is: –s ___________ –p ___________ –d ___________ –f ____________

Definitions Aufbau Principle--- electrons arrange to have the lowest energy so they fill from _______ energy to ________ energy Pauli Exclusion Principle---maximum of _______ electrons are in each orbital and they have ________ spins (shown by an up and down arrow in the orbital) Hund’s Rule---Fill ______ electron in each orbital all the way across then then go back to fill the second electrons if the electrons are available (think of filling a bus with one person in a seat first)

Orbitals Each orbital is shown as a box can hold a maximum of 2 electrons (one electron is represented with an “up” arrow and the other electron is represented with a “down” arrow) s has 1 orbital = _____ electrons p has 3 orbitals = _____ electrons d has 5 orbitals = _____ electrons f has 7 orbitals = ___electrons

Periodic Table

Using the Periodic Table

Order of electrons filling the orbitals

Electron Diagram Example

Definitions Electron configuration is the written summary of the arrangement of _______ in an atom 1s 2 2s 2 2p 6 3s 2 3p 3 Noble gas configuration is the short cut that saves you time (yeah!) but you have to know all three. Go to the noble gas in the row ________ your element. [Ne] 3s 2 3p 3

Carbon Example

Valence Electrons

Part II: Titanium Example (review)

F orbitals

Exceptions Chromium (Cr) and Copper (Cu) Rule: Filled and ½ filled sublevels are stable For these exceptions, one electron is “promoted” to make the other sublevel more stable

Chromium Example (Exception)