Lecture 2-The structure of an atom Flashcards
Z
Atomic number
A
Mass number
What are orbitals?
When e- occupy specific regions in space
What is it called when orbitals are grouped into families?
Shells
How do e- determine the properties of an atom?
By affecting reactivity + ability to form bonds
What is the kinetic isotope effect?
Where heavier isotopes react slightly more slowly , because of the strength of the bonds
Stable isotopes remain ……..?
Unchanged indefinitely
What do unstable isotopes undergo to obtain a stable nucleus?
spontaneous disintegration
What does spontaneous integration result in?
The emission of small particles and / or radiation
What do radioactive isotopes have?
High energy nucleus
What does a mass spectrometer do?
Measure the molecular weight of atoms/compounds by observing the m/z of ratios
What does half-life t1/2 mean?
The time taken for the activity of a given amount of a radioactive substance to decay to half of its initial value
What emits during alpha decay?
Helium nuclei
What emits during beta minus decay?
electron
What emits during beta plus decay?
positron (same mass of e-, but different charge)
What emits during gamma rays?
- gamma photons
- high energy EM radiation
What is capture process?
When a small particle (e-/neutron) collides + combines with a nucleus
PENETRATING POWER
Alpha
Beta
Gamma
Paper
Aluminium
Lead
Industrial applications of radioactive isotopes?
- Energy generation
- Sterilization of food + medical supplies (60Co)
- Imaging + gauging
Domestic applications of radioactive isotopes?
Smoke detectors using 241Am-alpha source
Medical applications of radioactive isotopes?
- Diagnostic
- Therapeutic
Why should a radioisotope used in diagnosis emit gamma rays of sufficient energy?
So it can escape the body + have a half-life short enough for it to decay away soon
- 99Tcm commonly used
- emits gamma + low energy beta particles
What isotopes are involved in myocardial perfusion imaging ?
201TICL
82Rb
99Tcm
-detection + prognosis of coronary artery disease
What isotope is involved in PET imaging?
18F-Fluoro-deoxy glucose
-measure cell metabolism
What are 18F-compounds used for?
Imaging DNA synthesis + hypoxia
What are the requirements for radioisotopes for therapy?
A strong beta emitter—->damage cells in a small area
-Can be implanted near a tumour / injected
What is radioiodine used for?
Diagnostics, overactive thyroid
What is 89SrCL used for?
Bone metastasis
