Chapter 4, Sec. 3 Arrangement of Electrons ___________________: the arrangement of electrons in an atom Electrons in atoms assume arrangements that have the _______possible energies. This makes them more __________. _____________________________: the lowest energy arrangement of the electrons for each element

Rules for Electron Filling of Orbitals ________________: an electron occupies the ___________energy orbital that can receive it __________________________: no two electrons in the same _____can have the same _____of four _________numbers

Rules for Electron Filling of Orbitals __________: orbitals of equal energy are each occupied by ________electron each before any orbital is occupied by a __________electron in the pair. All electrons in single occupied orbitals must have the __________spin state.

How to Write Electron Configurations Find the element on the periodic table Start with the lowest energy level, fill the sublevels with electrons until you get to your element The principle quantum number is written first, followed by the sublevel superscripted with the number of electrons in that sublevel

Blocks of Sublevels “n” 1 2 3 4 5 6 7 3d1

Exception You would expect chromium’s electron configuration to be: ______________________________ But it is more stable if the ___ sublevel is ___________, so what really happens is: _____________________as Cr “steals” a 4s electron and puts it in the 3d sublevel

Another Exception You would expect copper’s electron configuration to be: ________________________________ But it is more stable if the ___sublevel is ________, so what really happens is: ____________________ as Cu “steals” a 4s electron and puts it in the 3d sublevel Do other worksheet here

Exceptions The farther down the periodic table you go, the more _______________the exceptions to the filling order become. You will be fine in our class if you know the idea from elements _____and any of the lower ___or ____block elements.

Orbital Notation (Diagrams) Sometimes we want to see exactly which orbital is occupied, and specify the ____. Only ______electrons can be in any one orbital, and they must have ________ spins. Every orbital in a given sublevel gets ___ electron before any get ____, and they all have the _____spin before pairing up.

Orbital Diagram Directions Write the electron configuration. Write lines based on the orbitals. Represent the correct number of orbitals: One line for s, 3 lines for p, 5 lines for d, 7 for f Draw arrows to represent the electrons, filling according to Hund’s rule and the Pauli exclusion principle. Practice- For Oxygen:

Shorthand or Noble Gas Notation Noble gases: group _____elements _________________: The preceding noble gas’s configuration is followed by the rest of the element’s configuration Example: vanadium Practice more

Excited State vs. Ground State An atom is in an ________state when the electron configuration shows electrons in _________than normal orbitals. Na would normally be: ______________ An excited state could be ____________