Electron Configurations Notation for Electrons

Where Are the Electrons? Rutherford said they were outside the nucleus But how are the electrons organized in relationship to the nucleus The electrons are extremely important as they determine how an element reacts The organization of the electrons determines an elements physical and chemical properties

Niels Bohr a review Compares electrons orbiting the nucleus of an atom to planets orbiting around the sun. Electrons occupy distinct orbitals. Orbitals have certain energies and distances from the nucleus.

Erwin Schrodinger a review Regions where electrons are most likely found are called “electron clouds”. Different types of orbitals have different shapes and different levels of energy. Although difficult to understand, the results were spectacular! This new model of the atom explained the physical properties of atoms, and the Periodic Table, perfectly.

Principle Quantum Level (n) The quantum level is the energy level of the electron (shell); the 1st shell, 2nd shell Energy increases as you move out Each quantum level has sub levels of different shapes

Sublevels The number of sublevels is equal to the quantum level or energy level The first level energy level has one sublevel, The second energy level has two sublevels The third energy level has three sublevels

Sublevels Each orbital type holds a different number of electrons S shape has1 orbital for a total of total of 2 electrons P shape has 3 orbitals for a total of 6 electrons D shape has 5 orbitals for a total of 10 electrons F shape has 7 orbitals for a total of 14 electrons

Principle energy level (n) Type of shape Number of orbitals per type Orbitals and Electron Capacity of the First Four Principle Energy Levels Principle energy level (n) Type of shape Number of orbitals per type Number of orbitals per level(n2) Maximum number of electrons (2n2) 1 s 2 4 8 p 3 9 18 d 5 16 32

Summary First level of organization Second level of organization Energy level numbered 1-7 Second level of organization Energy levels broken into shapes The number of orbital is equal energy level Each shape has different number of orbitals Each orbital holds 2 electrons Electrons are placed in the lowest energy levels first

Putting the Electrons in Place Electrons are put in the lowest energy levels first The order is 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 5d, 4f, Note that the s orbitals in the next energy are filled before the d level Maximum electrons in each orbital are: S – 2 electrons P – 6 electrons D – 10 electrons F – 14 electrons

This chart gives the specific order that the energy levels are filled

Another Way to View the Order Each Dash Is an Orbital Which Can Hold 2 Electrons 2p__ __ __ 3s__ 3p__ __ __ 4s __ 3d __ __ __ __ __ 4p __ __ __ 5s __ 4d __ __ __ __ __ 5p __ __ __

Lets Try One Oxygen 8 Electrons 1 s 2 electrons 2 s 2 electrons 2 p 4 electrons The electron configuration can be written as 1s22s22p4

Lets Try Another Ca 20 Electrons 1s 2 electrons 2s 2 electrons 2p 6 electrons 3s 2 electrons 3p 6 electrons 4s 2 electrons 1s22s22p63s23p64s2