Electron Orbitals Electrons fill atomic orbitals in a

Electron Orbitals • Electrons fill atomic orbitals in a very particular way, moving from the nucleus out. • The orbitals / electrons closest to the nucleus have the lowest energies, thus they are filled first. • As more and more electrons are added, they must go to higher and higher energy levels. • With each increasing main energy level within an atom we find more and more orbitals with more sub-levels. • The simplest kind of orbital is the s-orbital. It is shaped like a sphere. • The next type of orbital is the p-orbital. The p-orbitals are dumbbell-shaped and are found on each of the three major axes of the atom, x, y, and z. • Each of the above orbitals is capable of holding only 2 electrons.

Sketch these figures.

• So, the s-orbital holds only 2 electrons. When it is filled, the next electron must go to a higher energy orbital. • Each of the p-orbitals holds two electrons. So the total electrons held in sublevel p is 6. • Likewise, since the d-orbital has 5 configurations, its maximum capacity is 10 electrons. • The “Diagonal Rule” is a “map” showing us the order that electron orbitals are filled and become occupied.

Diagonal Rule 2 Electrons per orbital 6 10 14 1 s Steps: 1. Write the energy levels top to bottom. 2. Write the orbitals in s, p, d, f order. Write the same number of orbitals as the energy level. 3. Draw diagonal lines from the top right to the bottom left. 4. To get the correct order, 2 s 2 p 3 s 3 p 3 d 4 s 4 p 4 d 4 f 5 s 5 p 5 d 5 f 5 g? 6 s 6 p 6 d 6 f 6 g? 6 h? 7 s 7 p 7 d 7 f 7 g? 7 h? follow the arrows! By this point, we are past the current periodic table so we can stop. 7 i?

Electron Configurations – Examples from Power. Point Packet H (1 e-) 1 s 1 Li (3 e-) 1 s 2 2 s 1 Ne (10 e-) 1 s 2 2 p 6 K (19 e-) 1 s 2 2 p 6 3 s 2 3 p 6 4 s 1 Zn (30 e-) 1 s 2 2 p 6 3 s 2 3 p 6 4 s 2 3 d 10 Pb (82 e-) 1 s 2 2 p 6 3 s 2 3 p 6 4 s 2 3 d 10 4 p 6 5 s 2 4 d 10 5 p 6 6 s 2 4 f 14 5 d 10 6 p 2 Note that the electron configuration contains the energy level (period / row) in which the element is found in the periodic table. Example: The highest energy level in krypton’s electron configuration is 4 (4 s 1), and krypton is found in period 4 of the periodic table. 4 s 1 means main energy level 4 and 1 electron in the s-orbital. Note that the 1 is NOT an exponent.