Electron Configurations

Schrodinger’s Quantum Model Principal Energy Levels - A region around the nucleus of an atom where the electron is likely to be moving. The principal energy levels (n) are assigned values in order of increasing energy The average distance of the electron from the nucleus increases with increasing energy levels. (1 is closest to nucleus.) There are 7 energy levels = 7 periods.

Energy Sublevels Energy sublevels can be thought of as a section of seats in a theater. The rows that are higher up and farther from the stage contain more seats, just as energy levels that are farther from the nucleus contain more sublevels. The number of energy sublevels is the same as the number of principal energy levels. 7 Sublevels are labeled __s___, ___p__, __d___, and __f___according to the shapes of the atom’s orbitals

Atomic Orbitals Atomic orbitals represent the electron probability clouds of an atom’s electrons. Each orbital may contain at most ____2____ electrons. All s orbitals are spherical All p orbitals are dumbbell-shaped 4 out 5 d orbitals are flower-shaped and one has a unique shape 7 f orbitals have different and very complex shapes

Shortcuts – Noble Gas Notation method – used to represent electron configurations of noble gases using bracketed symbols. Practice: Use shortcut method to write e-configurations for Ar and P.

Ar: [Ne] 3s 2 3p 6 or [Ar] P: [Ne] 3s 2 3p 3

Ground State vs. Excited State Ground State – The most stable, lower energy arrangement of the electrons in an atom. (The electrons are in the correct order of orbitals.) Excited State – When atom gains energy the electrons jump into higher energy level. Identify the following atoms and describe their state. (Ground or Excited) 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 3d 10 4p 3 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 5 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 8

Electron Configuration – How to show the arrangement of electrons Aufbau Principle – Electrons enter orbitals of lower energy first. 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p Pauli Exclusion Principle – No more than __2______ electrons can occupy the same orbital AND they must spin in opposite direction (Opposite spins help hold e - in an orbital by creating magnetic attraction.) Hund’s Rule – Orbitals of equal energy must EACH have _1____ electron with the same ____spin______ before any orbital is occupied by a 2 nd electron. Energy Level Increase

In your book. Copy table 5-2 on p. 134 Copy Figure 5-17 on p. 135