Chapter 7 Section 4 11 Quantum mechanics electrons are organized in atoms in very specific ways energy levels represent distances from the nucleus inside energy levels are orbitals that can hold 2 electrons the higher the energy level the more orbitals it can hold *before this electrons were thought to be in a cloud around the nucleus with no organization Heisenberg's uncertainty principle either the location or the energy of an electron can be known Determining one of the variables affects the other (finding the location changes the energy)
Orbital represent a volume where an electron is likely to be found probability density an orbital can hold 2 electrons Energy levels represent volumes at different distances from the nucleus 1st energy level is closest to the nucleus due to Coulombic attractions electrons want to be as near the nucleus as possible but still be far from other electrons Types of orbitals s orbital spherical shaped orbital The number is the energy level higher energy level, bigger orbital (each can still only hold 2 electrons) There is 1 s orbital in each energy level
p orbitals have 2 lobes (sides) and a nodal plane in the middle where there is a zero probability of finding an electron 3 p orbitals per energy level (none in the 1st) Named p x, p y, p z based on the axis which they lie on d orbitals have 2 nodal planes 5 d orbitals per energy level starts in energy level 3
f orbitals have 3 nodal planes 7 orbitals per energy level starts in energy level 4 Crazy shapes! Summary of orbitals Orbital # of Orbitals per Energy Level First Energy level that has the orbital s 1 1 0 p 3 2 1 d 5 3 2 f 7 4 3 Number of Nodes in the Orbital Summary of Energy Levels 2 Electrons per Orbital Energy Level Orbitals in Energy Level Total Number of Electrons in Energy Level 1 s 2 2 s, p 8 3 s, p, d 18 4 s, p, d, f 32 5 s, p, d, f 32
Electron Configuration shows the energy levels and orbitals that electrons occupy in an atom Electrons fill from inner orbitals (lower in energy) to outer energy levels # of Electrons Energy Levels Orbitals How many total e s? Which element? Remember! s orbitals have 2 e p orbitals have 6 e d orbitals have 10 e f orbitals have 14 e Determine the number of electrons an atoms has and fill up orbitals until you have all the e s placed
Writing Electron Configurations Magnesium Bromine Carbon Al +3 F 1 ** EXCEPTIONS! Atoms are more stable if orbitals are completely filled or empty However, half filled orbitals are a little more stable Chromium Copper
Noble Gas Configuration an abbreviated form of electron configuration that only shows the electron configuration that come after the previous Noble Gas Core Electrons Electrons in inner energy levels (represented by Noble Gas [ ]) Valence Electrons Electrons in the outer most energy level (the electrons that are shown in Noble Config.) Calcium Ru Ra S
Each orbital can hold two electrons, if there are two electrons in the orbital the electrons have opposite spins property that relates to how a material reacts to a magnetic field Orbital Box Diagrams show details on how e s fill orbitals of the same energy level e s will spread out to separate orbitals of the same energy level first, each will have an "up" spin e s will pair up only if there are no available empty orbitals second electron is "down" Fluorine Aluminum ` Boron
Use Noble Gas Configurations Fe Zn Ce Er I Transition Metals last electrons in are usually not the first ones out! Usually lose the s electrons before the d electrons! Zn 2+ Fe 3+ Cr 3+
Diamagnetic substances have no magnetic field due to all the electrons being paired the spins cancel out (same # ups as downs) Paramagnetic substances have a magnetic field due to having unpaired electrons Use orbital box diagrams and the noble gas notation to determine if the following are diamagnetic or paramagnetic Oxygen Iron V +2 V +3 Co +3
Hund's Rule the most stable arrangement of electrons is that with the maximum number of unpaired electrons (e s only pair if they need to) Pauli's exclusion Principle e s in the same orbital must have opposite spins each electron in an atom is unique the combination of energy level, orbital, suborbital (p x, p y, p z ), and spin must be different for every e in an atom (the first three can be the same but the last must differ!) The 3 p orbitals in the same energy level are degenerate they have the same energy (same with the 5 d and 7 f) Ground State vs. Excited State Ground state when all the electrons fill the lowest available energy levels and orbitals Excited state when one or more electrons occupies an outer orbital requires energy to happen Lithium ground state Lithium excited state
[Ar] What element? Para or Diamagnetic? How many unpaired e s if it makes a +3 ion? [Ar] 4s 3d Which element? What group and period? Nonmetal, transition metal, main group metal or metalloid? Para or Diamagnetic? Would +2 ion be Para or Diamagnetic?
Homework P. 330 #27, 77 79, 82, 83, 85, 86, 92, 94, 98