Search for notes by fellow students, in your own course and all over the country.
Browse our notes for titles which look like what you need, you can preview any of the notes via a sample of the contents. After you're happy these are the notes you're after simply pop them into your shopping cart.
Document Preview
Extracts from the notes are below, to see the PDF you'll receive please use the links above
Chapter 9
Electron
Configurations
Quantized Property: property that can only have certain values (not all values are
allowed)
...
Quantized
Electron’s energy in an atom is quantized
...
Electrons are found only in these fixed energy levels and nowhere else
...
• He thought electrons were found only in specific
shells or energy levels, and nowhere else
...
The first number we will look at is the electron shell
...
Some Points
▪ Shells are assigned
numbers starting at 1
...
▪ The larger the shell
number, the larger the radius
of the shell
...
(Excitation)
Eventually, the electron decays (loses energy) and returns to the lower
energy state
...
The amount of energy required for excitation
and that is emitted during decay is different
for each energy level
...
Shells closer to nucleus are lower in energy than shells further from nucleus
...
When creating Bohr Diagrams:
1) Indicate the correct number of protons and neutrons in the atom’s
nucleus
...
Examples:
(important first shell can only have 2 e- then afterwards additional shells can
only have a maximum of 8 e-)
1) Oxygen-16 (O)
2) Sodium-23 (Na)
3) Sodium-23 Cation (Na+)
4) Nitrogen-15 (N)
5) Chlorine-35 Anion (Cl–)
** You are responsible for knowing the first 18 (both atoms and ions – up to
Argon)
...
• These sublevles are named s, p, d, and f (memorize
the order of these letters)
...
ex) The 2nd energy level has 2 subshells
The 3rd energy level has 3 subshells
9
Electron Occupancy in Sublevels
• The maximum number of electrons in each of the
energy sublevels depends on the sublevel:
– The s sublevel holds a maximum of 2 electrons
...
– The d sublevel holds a maximum of 10 electrons
...
• The maximum electrons per level is obtained by
adding the maximum number of electrons in each
sublevel
...
The first electrons fill the energy
sublevel closest to the nucleus
...
• A partial list of sublevels in order of increasing
energy is:
➢ 1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p < 5s < 4d …
16
Filling Diagram for Sublevels
• The order does not
strictly follow 1, 2,
3, etc
...
• The sublevel is written followed by a superscript
with the number of electrons in the sublevel
...
18
Writing Electron Configurations
• First, determine how many electrons are in the
atom
...
• Arrange the energy sublevels according to
increasing energy:
– 1s 2s 2p 3s 3p 4s 3d …
• Fill each sublevel with electrons until you have
used all the electrons in the atom:
– Fe: 1s2 2s2 2p6 3s2 3p6 4s2 3d 6
• The sum of the superscripts equals the atomic
number of iron (26)
19
Blocks of Elements
• We can break the periodic table into blocks of
elements where certain sublevels are being filled:
– Groups IA/1 and IIA/2 are filling s sublevels, so they
are called the s block of elements
...
– Groups IIIA/13 through VIIIA/18 are filling p
sublevels, so they are called the p block of elements
...
Chapter 6
22
Noble Gas Core Electron Configurations
• Recall, the electron configuration for Na is:
Na: 1s2 2s2 2p6 3s1
• We can abbreviate the electron configuration by
indicating the innermost electrons with the symbol
of the preceding noble gas
...
We rewrite the
electron configuration:
Na: [Ne] 3s1
Core Notation
23
Valence Electrons
• The outermost energy level or shell (farthest from
the nucleus) in the atom is called the valence shell
...
(We don’t count electrons in the outermost d and f
sublevels when counting valence electrons
...
25
Identifying Valence Electrons
• Remember, valence electrons are electrons in
and p sublevels of outermost energy level only
s
Predicting Valence Electrons
• The Roman numeral in the American convention
indicates the number of valence electrons
...
– Group 14 elements have 4 valence electrons
– Group 2 elements have 2 valence electrons
27
Periodic Table of the Elements
28
Predicting Ionic Charges
• Metals tend to lose electrons
• Nonmetals tend to gain electrons
Memorize this!
• The charge of an ion is related to the number of
valence electrons on the atom
...
Na → Na+ + e-
• Metals lose their valence electrons to form ions
...
”
• This means all atoms want to have 8 valence electrons in order to be
more stable
...
• By losing their valence electrons, they achieve a
noble gas configuration
...
• Group VA/15 elements form 3- ions, group VIA/16
elements form 2- ions, and group VIIA/17
elements form 1- ions
...
• We can look at the size of atoms, or their atomic
radius
...
– Atomic radius decreases as you go left to right across
a period
...
• Atomic radius decreases as you travel left to right
across the periodic table because the number of
protons in the nucleus increases
...
40
Metallic Character Trend
• Metallic character is the degree of metal character
(malleability, high density, etc
...
• Metallic character decreases left to right across a period
and from bottom to top in a group
...
• In general, the ionization energy increases as you go
from the bottom to the top in a group of elements
...
• The closer the electron to the nucleus, the more
energy is required to remove the electron
...
7 (Pages 108-111)
Chapter 9 – Section 9
...
9 (Pages 295 – 312) (In
Section 9