THE PERIODIC TABLE AND ATOM STRUCTURE Flashcards
Components:
electric field and magnetic field
speed of light in a vacuum
c = 2.99792458 × 10^8 m/s
or 3.0 x 10 ^8 m/s
symbol for frequency
v
distance between two corresponding points on a wave
Wavelength
a technique that has been developed to the point that it can be carried out using handheld units.
X-ray fluorescence (XRF)
the small portion of the entire electromagnetic spectrum that our eyes can detect
Visible light
Light best described as a _____ when light is imparting energy to another object
Particle
As light intensity increases, the number of electrons increases ejected
e- versus l
Carbon can be detected in an X-ray fluorescence experiment by monitoring the emission at a wavelength of 4.47 nm
➢ What is the frequency of this light?
the small portion
of the electromagnetic radiation
spectrum detected by our eyes
Visible light
MEMO:
Low frequency
Long wavelength
Small amplitude
MEMO:
High frequency
Short wavelength
Large amplitude
is the number of cycles of the wave passing a given point per second, usually expressed in Hz
Frequency
two components to electromagnetic radiation
an electric field and a magnetic field
Described as a wave traveling through space
Visible light
a more accurate term for what we usually refer to simply as “light.”
Visible light
The photoelectric effect is used in
photocathodes
Below some threshold frequency or ν0, no emitted photoelectrons are
e- versus v
The fourth variable of light
velocity
Long wavelengths will have fewer cycles “pass by” in one second, so they will have ____ frequencies
lower
Depending on the situation, light is best described as a wave or a particle
Wave–particle duality
➢ Samples are decomposed into atoms
➢ Different elements absorb different frequencies of light, leading to their
identification
➢ Amount of light absorbed is related to the quantity of each element present
atomic absorption spectroscopy or AAS
has been described as a wave traveling through space
light
Light one form of electromagnetic radiation, which consists of
oscillating electric and magnetic fields.
The origin of the word electromagnetic lies in the
nature of light
The kinetic energy of emitted electrons is independent of light intensity
KE versus I
the size or height of a wave
amplitude
the distance between corresponding points on adjacent waves.
wavelength
Speed of light in a vacuum is
constant
➢ Speed of light changes
➢ Light bends at an angle depending on its wavelength
➢ Light separates into its component colors in order of their wavelengths
Refraction
Formula for c
c = λ × ν
The photoelectric effect is not explained using a wave description but is explained by
modeling light as a particle
Which plot in the photoelectron effect experiment is a step function?
* KE versus intensity
* KE versus wavelength
* Number of electrons versus intensity
* Number of electrons versus wavelength
- Number of electrons versus wavelength
determines the brightness of the light
amplitude
symbol for wavelength
λ
For which type of light bulb is the light generated by excited gas atoms?
* Incandescent bulb
* Halogen bulb
* Fluorescent bulb
- Fluorescent bulb
characteristics that can describe any wave
Speed, wavelength, frequency, and amplitude
can be carried out without the need to decompose or damage the sample
nondestructive testing
the distance between “peaks”
the distance between “valleys”
wavelength
an important tool for nondestructive trace analysis
Handheld X-ray fluorescence or XRF instrument
Formula for E
E = hv = hc/λ
If information about the elemental composition of a part that is being used in a construction project is required, the part cannot be destroyed to determine its composition. Hence, what nondestructive testing analysis should be used?
X-ray fluorescence (XRF)
the size or “height” of the wave
amplitude
- Forms of electromagnetic
radiation include
radio waves, microwaves, and X-rays
Light is described as a collection of packets of energy called
photons
it is a method that requires sample digestion
Atomic absorption spectroscopy (AAS)
Electromagnetic radiation can be categorized in terms of its
wavelength or frequency
occurs when light strikes a metal surface and causes electrons to be ejected
Photoelectric effect
➢ Frequency is _______ proportional to wavelength
inversely
As frequency increases, kinetic energy of emitted electrons increases linearly
KE versus ν
the number of complete cycles of the wave passing a given point per second
frequency
Light strikes the cathode and
ejects electrons
is the bending of a wave when it passes from one medium to another of different refractive index
Refraction
Frequency usually designated as ν and measured in units of
1/s, or hertz (Hz).
Ejected electrons are collected at the
anode
In XRF, Atoms in the sample are excited with
X-rays
➢ Energy from the light is transferred to the electrons in the metal
➢ With sufficient energy, electrons break free from the metal
➢ When more energy is given to electrons, they travel faster and have higher kinetic energy as they leave the metal
Photoelectric effect
defined as the product of frequency and wavelength
speed of light
The lower wave in has a _____ amplitude than the upper
wave.
larger
The energy of a photon, E, is proportional to its frequency, ν
It is inversely proportional to the wavelength, λ
In order to understand why a particular material, such an alloy, failed during the manufacture or use of a product requires ________ to detect chemicals that are present at extremely low levels in the alloy.
Trace analysis
correspond to the color of the light
wavelength and frequency
is the bending of a wave when it passes from one medium to another of different density
Refraction
Many trace analysis techniques rely on _______________ and take advantage of the fact that atoms of different elements have specific and characteristic properties
microscopy or spectroscopy
➢ Atoms in the sample are excited with X-rays
➢ Atoms then lose the excess energy by fluorescence, frequencies of which are characteristic for each element
➢ Fluorescence intensity is related to the quantity of an element present
Handheld X-ray fluorescence or XRF instrument
Parts of Electromagnetic Spectrum
- Amplitude
- Wavelength
- Nodes
- Electric vector
- Magnetic vector
- Direction of propagation
is the energy holding an electron to a metal
Binding energy
Particular pattern of wavelengths absorbed and emitted by an element
Atomic spectra
Electrical current dissociates molecular H2 into excited atoms, which emit light that separates into ______ after being passed through a prism
four discrete wavelengths
