Atomic and Nuclear Phenomena

photoelectric effect

E = hf = hc/wavelength

photoelectric effect kinetic energy

hf - W, max KE of ejected electron, W is minimum energy required

mass defect

difference between the sum of the masses of nucleons in the nucleus and the mass of the nucleus, results from conversion of matter to energy as binding energy

IR spectroscopy

helps determine chemical structure because of different bonds absorbing different wavelengths

UV-Vis spectroscopy

looks at absorption of light

Z

atomic number, number of protons

A

mass number, number of protons + neutrons

electron capture

capture inner electron that combines with proton to form neutron

half life

n = n0e^(-decay constant x t)

decay constant

0.693/half life time

alternative half life formula

Nt = N0 (0.5)^(t/t0.5)

alpha decay example 238/92U

234/90Th + 4/2He

alpha decay

emission of alpha particle 4/2 He

beta-minus decay example 137/55Cs

137/56Ba + 0/-1e- + ve

beta minus decay

neutron converted to proton and beta minus particle

beta-plus decay example 22/11Na

22/10Ne + 0/+1e+ + ve

beta plus decay/positron decay

proton converted to neutron and beta particle

gamma decay example 12/6C*

12/6C + 0/0Y

gamma decay

emission of gamma rays

speed of light c

3 × 10^8 m/s

electron moves from higher to lower orbital

emits photon, decreases total energy of atom, closer to nucleus

electron moves from lower to higher orbital

absorbs photon, increases total energy of atom, moves further from nucleus

visible light

400-700 nm

gamma rays

10^-16 wavelength

xrays

10^-10 wavelength

UV

10^-8 wavelength

IR

10^-4 wavelength

microwave

10^-2 wavelength

wavelength rankings

gamma < xray < UV < visible < IR < microwave < radio