Chemistry Chapter 5 Notes #3

Rules Neils Bohr Added on to Planck’s and Einstein’s theories Lowest available energy state of an atom Ground State When an atom gains energy = Excited State This applies to the Atomic emission spectra!!

Rules Heisenberg Uncertainty Principle It is fundamentally impossible to know precisely both the velocity and the position of a particle at the same time Ex. Blades of a running fan (on high) That is how the electrons are traveling

Rules Aufbau Principle Electrons “fill” atoms starting at the lowest energy and moving out to higher amounts of energy Excited vs. Ground State

Rules Pauli Exclusion Principle A max of 2 electrons will occupy a single orbital The electrons have opposite spins The opposite spin requirement is born out of quantum physics….2 electrons cannot have the same quantum number – therefore they must have opposite spins

Rules Hund’s Rule Single electrons with the same spin occupy each orbital (of a multi-orbital sublevel) before additional electrons with opposite spins occupy the same orbital. Remember – Electrons are all negative – so they repel each other –meaning they take as much space as they can…

“Blocks on the table!

Noble gas Configuration Shorthand to electron configuration Steps: Find the noble gas that comes directly before the element you are looking at Put the chemical symbol of the noble gas in brackets Then, continue the electron configuration at the beginning of the row immediately following the noble gas

Noble gas Configuration ElementAtomic # e - confNoble gas Conf. Na11 Ca20 Sr38 P15 Br35 I53