Topic 2: Atomic Structure Flashcards
Proton
a) Relative charge
b) Relative mass
c) Location
a) +1
b) ~ 1
c) Nucleus
Neutron
a) Relative charge
b) Relative mass
c) Location
a) 0
b) ~ 1
c) Nucleus
Electron
a) Relative charge
b) Relative mass
c) Location
a) -1
b) 1/1836
c) Outside the nucleus in the electron cloud
Nuclear Symbol (aka Standard Atomic Notion)
Shows the chemical symbol, the mass number and the atomic number of the isotope.
Atomic Number (Z).
- # Protons of an atom
- Same atomic number for all the elements
Mass Number (A).
of protons + # of nuetrons
Isotope
Atoms with the same number of protons but different number of neutrons.
(They are different versions of the same element. They behave the same chemically but physical properties may vary.)
Relative atomic mass (Ar)
Ratio of the average mass of the atom to the unified atomic mass unit
Radioisotopes
Unstable form of a chemical element that releases radiation as it breaks down and becomes more stable.
Three types of nuclear radiation
a) Alpha
b) Beta
c) Gamma
Alpha radiation
Alpha radiation occurs when the nucleus of an atom becomes unstable (the ratio of neutrons to protons is too low) and alpha particles are emitted to restore balance.
Beta radiation
Beta radiation (symbol β), is a high-energy, high-speed electron or positron emitted by the radioactive decay of an atomic nucleus during the process of beta decay.
Gamma radiation
Gamma rays are a form of electromagnetic radiation (EMR).
Uses of radioisotopes
- Nuclear medicine for diagnostics, treatment and research
- “Chemical clocks” in geological and archaeological dating
- “Tracers” in biochemical and pharmaceutical research
- PET (position emission tomography) scans to give 3-D images of tracer concentration in the body and can be used to detect cancers
Isotopic Abundance
The percentage of an isotope in a sample of an element.
Mass Spectrometer
Used to identify isotopes and their relative abundance.
Stages of mass spectrometer
- Vaporization
- Ionization
- Acceleration
- Deflection
- Detection
Mass spectrometer: Vaporization
- all particles passing through get converted to gaseous state
- high vacuum here so particles don’t collide with air
Mass spectrometer: Ionization
- the gaseous atoms are bombarded with high-energy electrons
- to generate positively-charged species
e.g. X (g) + e- -> M+ (g) + 2e-
Mass Spectrometer: Acceleration
- the ions are attracted to positively-charged plates
- thus they’re accelerated in the electric field
- so they all have the same KE
Mass Spectrometer: Deflection
- the positive ions are deflected by an electromagnetic field
- degree of deflection depends on mass-to-charge ratio
- high deflection: low mass, high charge
Mass Spectrometer: Detection
- the beam of ions passing through the detector plate is electrically detected
- species of a particular m:z ratio are identified
- results are called “mass spectrum”
Electromagnetic Spectrum
A spectrum of wavelengths comprised of the types of electromagnetic radiation
Properties of electromagnetic radiation
- has electric and magnetic fields that oscillate perpendicularly to each other and to the direction of travel
- behaves like both a particle and like a wave
- velocity of EM waves = velocity of light
- can travel in a vacuum
Characteristics of red light
- High wavelength
- low frequency
- low energy
Characteristics of violet/purple light
- low wavelength
- high frequency
- high energy
Electromagnetic Spectrum (EMS)
Is a spectrum of wavelengths that comprimise the various types of electromagnetic radiation.
Eg. Visiable light, radio waves, X-rays, microwaves, infrared radiation (IR), ultraviolet radiation (UV) etc.
Relation of energy, wavelength, and frequency
a) Energy is inversely proportional to wavelength
b) Energy is proportional to frequency
c) Energy, E, of radiation is inversly proportional to the wavelength (Formula 🠪 E ∝1/vλ)
d) Wavelength (λ) is inversly related to frquency (v). (Formula 🠪 c=vλ, c = speed of light = 3.00 x 10^-8 m s^-1)