Electromagnetism and Atomic Structure: A Comprehensive Guide

Isotopes

• Same elements with different numbers of neutrons

Ions

• Same element with an unequal number of protons and electrons

Electric Fields

Things with charge (protons and electrons) generate electric fields (E) (Likewise, electric fields can affect things with charge)

Energy and Matter

When atoms or molecules “happen across” energy, [usually] 1 of 2 things can happen: 1) they wiggle-jiggle more [we classify the amount of “wiggling-jiggling” by the quantity of temperature] 2) the energy, if it is a) in the form of a special type of electromagnetic field and b) of a specific frequency, can be absorbed

λ∙f = c

λ = wavelength of the wave [m]

f = frequency of the wave [Hertz, Hz=1/s]

c = speed of light = 3∙108 m/s

Electromagnetic Waves can also be thought of as [massless] Electromagnetic Particles [a.k.a., Photons]

E = h∙f = h∙c/λ

E = energy of the wave [J]

h = Planck’s constant = 6.626∙10-34 J∙s

"All things glow" means everything is producing EM and therefore energy and heat

Wien's Law: λmax∙T=0.0029 [m∙K]

λmax = wavelength of maximum energy emission

T = temperature of the object

Stefan's Law: P = E/Δt =ε∙σ∙A∙T4( as T goes up, total E emitted goes up)

ε = object’s emissivity (ranges from 0 to 1)

σ = the Stefan-Boltzmann constant

A = the objects surface area

T = temperature of the object

Black Body

• Constant temp

• Uniform composition

• Exactly distributed

• Lots of atoms

• Not real

• Conversely, all normal matter absorbs electromagnetic radiation to some degree. An object that absorbs all radiation falling on it, at all wavelengths, is called a black body. When a black body is at a uniform temperature, its emission has a characteristic frequency distribution that depends on the temperature.

Subatomic Particles

• Proton

  • Positive charge

  • +

• Neutron

  • No charge

  • n

• Electron

  • Negative charge

  • e-

Radioactive Decay

• Alpha Particles

  Are released by high mass, proton-rich unstable nuclei. The alpha particle is a helium nucleus; it consists of two protons and two neutrons. It contains no electrons to balance the two positively charged protons. Alpha particles are therefore positively charged particles moving at high speeds.

• Beta Particles

  Are emitted by neutron-rich unstable nuclei. Beta particles are high energy electrons. These electrons are not electrons from the electron shells around the nucleus but are generated when a neutron in the nucleus splits to form a proton and an accompanying electron. Beta particles are negatively charged.