Transcript Electron Configuration Notes

Electron Energy Level Notes
Electron Energy Level Notes
• Electrons do not travel around the nucleus
of an atom in orbits
• They are found in ____ ____at different
distances away from the nucleus. (kind of like
shells or layers).
energy levels
The Quantum Mechanical Model of the Atom (cont.)
The wave function predicts a three-dimensional region around the
nucleus called an _______.
orbital
Hydrogen Atomic Orbitals
Electrons cannot exist between energy levels (just like the rungs of a ladder).
The ______ _______ ______(n) indicates the relative size and
energy of atomic orbitals.
principal quantum number
n specifies the atom’s major energy levels.
Electron Energy Level Notes
• Energy levels are broken up into
sublevels:
• There are at least 4 possible types of
sublevels—given labels: __, __, __,or __.
s, p, d, f
Hydrogen Atomic Orbitals (cont.)
Energy sublevels are contained within the principal energy levels.
Energy Levels and Sub-levels
d) Ex. Orbitals around the Nucleus of a
Neon Atom
Electron Energy Level Notes
• Only a certain number of electrons may
exist in an energy level, but the number
varies. It can be determined by:
• # of electrons in level = 2 x (# of energy level)2
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Therefore:
energy level 1 = 2 (1)2 = 2
energy level 2 = 2 (2)2 = 8
energy level 3 = 18
energy level 4 = 32
etc...
Electron Energy Level Notes
• In each energy level, electrons fill sublevels in a
certain order
• Level 1:
• only has one s sublevel (a spherical shape)
• 2 electrons may fit in this sublevel--each one has
an opposite “spin”, allowing them to take up the
same space
• Pauli exclusion principle—no more than 2
electrons may be found in the same orbital
(“orbital” means a particular location)
s-Orbital Image
Electron Energy Level Notes
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Level 2:
has two sublevels: s and p
2 electrons in s
there are 3 different p orbitals, and may hold 2
electrons each—6 total.
• total of 8 overall in Level 2
p-Orbital Image
Electron Energy Level Notes
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Level 3:
has 3 sublevels: s, p, and d
2 electrons in s
6 electrons in p
there are 5 different d orbitals, and 2 electrons
can fit in each—total of 10. (look at picture of d
orbitals, imagine how they can fit together)
• total of 18
d-orbital notes
Hydrogen Atomic Orbitals (cont.)
Each energy sublevel relates to orbitals of different shape.
Image of orbitals
Electron Energy Level Notes
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Level 4:
has 4 sublevels: s, p, d , and f
2 electrons in s
6 electrons in p
10 electrons in d
14 electrons in f (7 different orbitals for f)
total of 32
f
s
p
s
p
4
3
d
s
2
s
1
d
p
4 sublevels
1+3+5+7=16 orbitals
2 + 6 + 10 + 14 = 32e3 sublevels
1+3+5=9 orbitals
2 + 6 + 10 = 18e2 sublevels
1+3=4 orbitals
2 + 6 = 8e1 sublevel
1 orbital
2e-
Hydrogen Atomic Orbitals (cont.)
Electron Energy Level Notes
• The order that electrons fill up orbitals
does not follow the logical order of all 1’s,
then all 2’s, then all 3’s, etc.
• They follow the order found on pg. 156.
Order of Orbitals
Electron Energy Level Notes
• An easy way to remember this is to use
the periodic table--it is arranged to show
how these orbitals are filled.
Order of Orbitals—Periodic Table
Ground-State Electron Configuration
The arrangement of electrons in the atom is called the electron
configuration.
The aufbau principle states that each electron occupies the lowest energy
orbital available.
Ground-State Electron Configuration (cont.)
The Pauli exclusion principle states that a maximum of two electrons
can occupy a single orbital, but only if the electrons have opposite
spins.
Hund’s rule states that single electrons with the
same spin must occupy each equal-energy
orbital before additional electrons with
opposite spins can occupy the same energy
level orbitals.
Electron Energy Level Notes
• Hund’s rule is used for filling orbitals with
electrons. It states that only one electron
will be put in each orbital of a sublevel until
all of them are filled, and after that, they
may be paired up until the sublevel is full.
Ground-State Electron Configuration (cont.)
Section 5-3
Ground-State Electron Configuration (cont.)
Section 5-3
Noble gas notation uses noble gas symbols in brackets to shorten
inner electron configurations of other elements.
Ground-State Electron Configuration (cont.)
Section 5-3
The electron configurations (for chromium, copper, and several other
elements) reflect the increased stability of half-filled and filled sets
of s and d orbitals.
Valence Electrons
Section 5-3
Valence electrons are defined as electrons in the atom’s outermost
orbitals—those associated with the atom’s highest principal energy
level.
Electron-dot structure consists of the element’s symbol representing the
nucleus, surrounded by dots representing the element’s valence
electrons.
Valence Electrons (cont.)
Section 5-3