Atomic And Nuclear physics Flashcards
Discovered that electrons could exist in certain specific states of definite energy without radiating away energy, if a certain condition was met by the orbit radius
Bohr
Geiger and Marsden’s alpha particles were largely deflected when the nucleus was approached at
Very short distances
Energy in electrons is thus… Because they lose energy when making a transition from one state to another of lower energy, and this emitted value equals the difference between states
Discrete
Under normal conditions, electrons occupy
Ground state
The set of wavelengths of emitted light by the atoms of an element is the
Emission spectrum
Electrons take energy and use it in order to make a transition. The wavelengths that are absorbed make the
Absorption spectrum
Number of protons in a nucleus is called the
Atomic number
Total number of nucleons in atom (protons+neutrons)
Mass number
Nuclei that have same atomic number but different mass number
Isotopes
Alpha, gamma, and beta radiations…. Air as they pass through it; knock electrons out of atoms
Ionise
Positive emissions; identical properties to helium nucleus. Mass number = 4 and atomic number = 2
Alpha
Negative emissions, identified as electrons.
Beta
Neutral emissions, identified as photons with small wavelengths
Gamma
Photons have wavelength of
hc/E
The number of nuclei that will decay per second is proportional to the number of atoms present that have not yet decayed.
Law of radioactive decay
Mass defect of the nucleus has been converted into …. And is stored in the nucleus
Binding energy
Binding energy equivalent to a mass of 1u
931.5 MeV
Produces neutrons, which can be used to collide with other nuclei producing a chain, self sustained reaction.
Fission when critical mass is present
….Creates… So that electrostatic repulsion between the two nuclei can be overcome
Fusion / plasma
Photoelectric effect; …. Of emitted light does not affect the energy of the emitted electrons
Intensity
Photoelectric effect; electron energy depends on… Of incident light and there is a certain minimum…. Below which no electrons are emitted
Frequency
Electrons are emitted with no time delay
Photoelectric effect
Energy of light quanta is given by
E=hf
If a photon of frequency f is absorbed by an electron, the electron’s energy will increase by
hf