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Electron Subshell Fill Order
Biology (Bio202)
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Module 4:
The outer “shells” are the layers of energy around the nucleus.
The subshells – s,p,d,f – determine the shape.
SHELL SUBSHELL CONTENT MAX # OF ELECTRONS
1st 1s 2
2nd 2s + 2p 2 + 6 = 8
3rd 3s + 3p + 3d 2 + 6 + 10 = 18
4th 4s + 4p + 4d + 4f 2 + 6 + 10 + 14 = 32
5th 5s + 5p + 5d + 5f 2 + 6 + 10 + 14 = 32
6th 6s + 6p + 6d + 6f 2 + 6 + 10 + 14 = 32
7th 7s + 7p + 7d + 7f 2 + 6 + 10 + 14 = 32 etc
Valence Electrons: Total number of electrons in the highest energy shell
Electron Subshell Fill Order:
1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f,
6d, 7p....
Ex: 26 Fe = 1 s
❑ 2
2 s
2
2 p
6
3 s
2
3 p
6
4 s
2
3 d
6 - 2 valence
electrons
Ex: 13 Al = 1 s
❑ 2
2 s
2
2 p
6
3 s
2
3 p
1 - 3 valence electrons
1
s
2
s
2p
3
s
3p 3d
4
s
4p 4d 4f
5
s
5p 5d 5f
6
s
6p 6d
7
s
7p
Ex: 33 As = 1 s
❑ 2
2 s
2
2 p
6
3 s
2
3 p
6
4 s
2
3 d
10
4 p
3 - 5 valence electrons
Ex: 18 Ar = 1 s
❑ 2
2 s
2
2 p
6
3 s
2
3 p
6 - 8 valence electrons
Orbital Diagrams:
Each orbital can hold 2 electrons, so an “s” subshell will contain 1 orbital (2 electrons)
“p” subshell 3 orbitals (6 electrons – 3 orbitals x 2 electrons)
“d” subshell 5 orbitals (10 electrons – 5 orbitals x 2 electrons)
“f” subshell 7 orbitals (14 electrons – 7 orbitals x 2 electrons)
p-orbital cut by 1 nodal-plane
d-orbital cut by 2 nodal-planes
f-orbital cut by 3 nodal-planes
For simplicity, we will indicate the orbitals of subshells as horizontal lines, as shown below:
Orbital Content
Any “s” subshell __
Any “p” subshell __ __ __
Any “d” subshell __ __ __ __ __
Any “f” subshell __ __ __ __ __ __ __
Orbital Filling: ** Fill electrons into the separate orbitals with the up arrows being filled first, and then go back and fill the
####### down arrows. The un-paired up arrows remaining once all electrons are accounted for represent “unpaired electrons”
Ex: 26 Fe = 1 s
❑ 2
2 s
2
2 p
6
3 s
2
3 p
6
4 s
2
3 d
6 - 2 valence electrons
-The frequency (v) of the wave is the number of crests that pass a given point within 1 second. -A Hertz (Hz) = One wave (or cycle) per second, named after Heinrich Hertz, who established the existence of radio waves. -A radio wave with 1,000,000 cycles that pass a point in one second has a frequency of 10 6 Hz.
-The period (p) of a wave = the time it takes for one cycle to pass, and the units are always in terms of time. -The faster a wave moves, the smaller its period -The speed (c) of electromagnetic radiation in a vacuum is a constant 2 x 10 8 meters per second (m/s) = product of its frequency times its wavelength: ν x λ = c = 2 x 10 8 m/s
Long wavelength radiation (like radio transmission waves) must have a low frequency,
Short wavelength radiation (like x-rays) must have a high frequency.
(ν x λ = c), which relates wavelength, frequency, and velocity of electromagnetic radiation, makes it possible to calculate frequency if wavelength is known (or vice versa). v = frq, λ = wavelength, c = speed
Examples:
What is the wavelength of a radio wave with v = 6 x 107 Hz?
λ =
c
v
=
2 x 1 0
8
m / s
6 x 10
7
cycles / s
=4 m
What is the frequency of infrared light with λ = 2 x 10-5 m?
v =
c
λ
=
(
2 x 1 0
8
m / s
2 x 10
− 5
m )
=1 x 10
13
Hz
ionizing radiation - harmful to human tissues. Ex: gamma rays, X-rays, and some wavelengths of ultraviolet light. Radio transmission waves, microwaves, infrared light, and visible light are normally considered non-ionizing radiation, though high intensity beams of these can have similar properties as ionizing radiation. Ionizing radiation is found naturally in the environment in naturally occurring radioactive materials and cosmic rays. Man-made sources include artificially produced radioisotopes and X-ray tubes, which are used, under controlled conditions, in medical treatment and diagnosis. Uncontrolled exposure to ionizing radiation can cause fetal mutation, radiation sickness, cancer, and death
electromagnetic radiation behaves like a wave and shows wave properties such as interference and diffraction.
Diffraction is the slight bending of waves around the edge of any object in their path. Light is bent around tiny water droplets found in clouds, producing light and dark bands that constitute the coronas surrounding the sun or moon.
Interference is the combination of waves to form alternating areas of increased and decreased amplitude. This is the principle that creates beats in sound wave production.
Diagram of Diffraction:
Diagram of Interference:
**Electromagnetic Radiation exhibits a wave/ particle duality – has properties of both waves and particles.
-Particles of light are called photons, just as the atom is the smallest unit of matter and the electron is the smallest unit of electricity. -Unlike the electron, which has one unit of negative electric charge, the photon is uncharged. -The particle property of light is called the photoelectric effect
- Photoelectric effect occurs when visible light interacts with alkali metals causing electrons (called photoelectrons) to be emitted. This property is taken advantage of in automatic door openers.
4 – Quantum Numbers
The electron energy levels in an atom are quantized, as theorized by Bohr in 1913
In 1924, Louis de Broglie, a French graduate student, explained quantization was due to the wave properties of electrons. De Broglie proposed that electrons behave as standing waves because they are held in place by the positively charged nucleus.
Standing waves, like guitar string vibrations, are confined to a region of space and do not move from place to place as traveling waves like water waves do. A diagram of standing waves created on a string that is attached at each end within a box is shown below:
Quantum numbers are a set of 4 symbols with a numerical value that distinguish an electron from another electron. Each electron can be described by four quantum numbers as listed below, with each quantum number describing a particular aspect of the electron:
Quantum # Symbol Description Values Principal QN n Shell 1,2,3,4, etc
Ex: 33 ❑ As = 1 s 22 s 22 p 63 s 23 p 64 s 23 d 104 p 3
↑ ↓
1 s
↑↓
2 s
↑ ↓
❑
↑ ↓
2 p
↑↓
❑
↑ ↓
3 s
↑ ↓
❑
↑↓
3 p
↑ ↓
❑
↑↓
4 s
↑ ↓
❑
↑ ↓
❑
↑ ↓
3 d
↑ ↓
❑
↑↓
❑
↑
❑
↑
4 p
↑
❑
“outermost” and “last to fill” electron is 4p 3
Quantum #s for 4p 3 :
4 – Periodic Properties
**The properties of an atom are most often dependent on the structure/arrangement of the electrons
3 atomic properties:
-Ionization energy: a measure of how much energy is needed to remove an electron from an atom and make it a positive ion.
This property decreases as you go down a vertical column of elements because the elements are becoming larger and less energy is needed to remove an electron that is farther away from the attracting nucleus.
This property increases as you go left to right across a horizontal row of elements because more energy is needed to remove an electron that is being attracted by a greater nuclear charge.
-Electronegativity: A measure of the attraction an atom has for its outer shell electrons.
This property decreases as you go down a vertical column of elements because the elements are becoming larger and the outer shell electrons are more distant from the attracting nucleus.
This property increases as you go left to right across a horizontal row of elements because the greater nuclear charge holds the outer shell electrons more tightly.
***Metals have a relatively low electronegativity and nonmetals have a relatively high electronegativity.
-Atomic Size: The distance from the center of the nucleus to the outer shell of an atom.
This property increases as you go down a vertical column of elements because the elements have outer shell electrons that are more distant from the nucleus.
This property decreases as you go left to right across a horizontal row of elements because the greater nuclear charge holds the outer shell electrons more tightly together.
***Metals have a relatively low electronegativity and nonmetals have a relatively high electronegativity.
n (shell) l (sub-shell) ml ms n = 4 l = 1 ml = +1 ms = +1/
Electron Subshell Fill Order
Course: Biology (Bio202)
University: Chicago School of Professional Psychology
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