Lecture 2 Flashcards
What determines the identity of the atom?
.
What is atomic number?
.
What letter represents the atomic number?
Z
What is the orbit named after?
.
How is the orbit named?
.
What is the closest shell to the nucleus?
K shell
Tungesten
Atomic # 74
Atomic Mass 184
Letter = W
What determines the number of orbits?
The number of electrons
The closer you are to the nucleus…
The more the e- are tightly bound
K shell is closest
What is binding energy?
Energy required to remove an e-
Related to the Atomic Number
The higher the atomic number, the greater the attraction to the atomic nucleus
More energy is required when?
To remove an E- from a K shell than an outer shell
but could be different when comparting two atoms
Higher Z number =
More tightly bound the protons are
The more energy needed to remove an e- from an orbit
What is ionization?
Process of forming a positive and negative ion by removal of an electron from an neutral atom
How much energy??/
Slide 9
Binding energy or more
Go over slide 10
.
What is Radiation?
The transmission of energy through space and matter
Radiation occurs in:
2 forms
Wave Theory
or
Quantum Theory
What is Wave Theory?
Wave theory explains the propagation of radiation and the quantum theory explains the interaction of radiation with matter.
What is Electromagnetic Radiation?
Movement of energy through space as a
combination of electric and magnetic fields.
Electromagnetic Radiation starts with?
Radio Waves 10^3
When does Electromagnetic Radiation start to ionize?
At the Ultraviolet divide
We have to be more protected against…
Ionizing Radiation
What is Ionizing?
Have sufficient energy to eject an electron from the shells
What is Non-Ionizing?
Does not have sufficient energy to eject an electron from the shells
Wavelength and Frequency are?
Inversely Proportional
What is Wavelength?
Distance between two successive crests
What is Frequency?
Number of wavelength passing a particular point in time
Speed of Light Formula (c) =
Frequency (Hz) * Wavelength (m)
Quantum Theory of Radiation :
Particles
E =
energy, measured in e- volts
Quantum Theory of Radiation …
▪ Considers radiation as small discrete bundles of energy called
photons.
▪ Each photon has energy (eV), mass and travels in straight lines at the
speed of light.
▪ Electrically charged (except neutrons)
High Frequency =
Short Wavelength = High Energy
Alpha
+2
Beta +
Positron
+1
Beta -
Electron
-1
Electron
-1
What is Ionizing Rate?
▪ Rate of loss of energy from a particle as it moves through matter
What does Ionizing Rate Depend on?
▪ Depends on velocity, charge and size.
– Lower velocity, higher charge and bigger size → Greater LET
Ionizing Rate :
Linear Energy Transfer (LET)
Lower LET =
Further it travels
What are X-rays
▪ They are weightless packages of pure energy (photons) without an
electrical charge which travel in waves with a specific frequency and
wavelength at the speed of light (3x10
8m/sec) and are able to ionize
matter.
What are the properties of X-rays?
- Invisible, weightless, no electric charge
- Travels in straight lines.
X-ray beam diverges over distance. - Travels at the speed of light
- Highly penetrating (short wavelengths)
0.01 nm to 0.1 nm - Invisible, weightless, no electric charge
- Travels in straight lines.
X-ray beam diverges over distance. - Travels at the speed of light
- Highly penetrating (short wavelengths)
0.01 nm to 0.1 nm
Difference between Ionization and Excitation
Excitation:
▪ When the transferred energy is not sufficient to overcome binding
energy, e
-
is NOT ejected
▪ Receiving e
is raised to higher energy level within the orbit.
Instantaneously gives up this excess energy and returns to ground
level
Ionization:
Energy needed to displace something
Excitation:
Energy moves something around but does not displace it
