Introduction Flashcards
Spectroscopy
Study of the interaction between light and matter through qualifying and quantifying radiation that is absorbed emitted or scattered.
Electromagnetic wave
A mutual induction of electric and magnetic fields. Which are generated by a moving charged particle and the flucuation between an electric and magnetic fields over time
Photon
An object btwn a particle and wave which has an energy proportional to the radiation wave frequency
E=hv
h is the Planck’s constant 6.626 x 10-34 J s
C
λ
v
T
C=Light Speed = 299,797,2 458 m/s C = λv
or 2998・10 5 m /s
λ = Wavelength = Distance of a single wave
v = Frequency = the number of wave maxima crossing an imaginary surface perpendicular to the propagation direction (s -1) or Hz (1 Hz = 1 s-1) V = 1/T
h =
T = Period = Period (s) the time the wave electric or magnetic field takes to complete an oscillation
Electric Field
Movement (attraction or repulsion) of a charged particle creates an electric force, An electric field is the result of a charged particle. The force of a particle divided by a charge
Magnetic field
A charged particle in motion creates a magnetic field. True source is the time changing electric field. A force divided by a charge and by a velocity
Light Intensity - as a particle
Energy carried in a unit per time per space. Density of photons by the speed of light. Measured as W/m2
I = Uc
c =λv
Wavelength and frequency are always
inversely proportional so 𝜆 = 𝑐/𝜈 and 𝜈 = 𝑐/𝜆
and Wavenumber 𝜈’ = 1/
𝜆
E = hv
Einstein’s law of photon
energy)
This formula gives the energy which a photon carries. Energy = Planks constant (h) times frequency or E = hc/λ
Light Intensity
I = Uc
Intensity (as a particle) = Radiation energy density (U=Ed) * speed of light.
Intensity (as a wave) = ½ c e0E0^2
b/c U as a wave = ½e0*E0^2
Where E0 is the maximum electric field value of the radiation.
The energy carried by radiation through 1 m 2 in 1 s. It is proportional to the square of the electric field.
h or Planks Constant
6.626 ・ 10-34 J s
Defines the quantum nature of energy and relates the energy of a photon to its frequency
Chemical symbol of elements
A = top left = Mass number. The number of neutrons +
protons present in the nucleus.
Z = bottom left = Atomic number which is equal to the number of neutrons in the atom. Atoms with the same
atomic number are chemically identical
X = Chemical symbol of an element expressed as Letter(s)
Proton, Neutron, Electron
Neutron = Mass is 1.6748 x 10^-24 g Charge is neutral
Proton = Mass is 1.6725 x 10^-24 g Charge is + 1 e, corresponding to +1.602 x 10-19 C
Electron = mass is 9.108 x 10^-28 g charge is -1 e, corresponding to -1.602 x 10^-19 C
Atomic mass unit
Amu or u
The mass corresponding to 1/12 of the mass of the
isotope 12C. Carbon12 equals 12u.
1 u = 1.661 x 10^-24 g
Isotope
Atoms having the same atomic number, but different mass number, i.e., the same
number of protons, but different number of neutrons.
Cations and Anions
Cations = Ions with positive charge = less electrons than pro
Anions = Ions with negative charge = more electrons than pro
An atom is more or less likely to become a cation or anion according to its atomic number. The atoms on the top-right of the periodic
table are called non-
metals, and are electron-withdrawing. The atoms on the bottom-left are metals,
and loose easily electrons.
Ionic bond or compound
Chemical bound formed by positive and negative ions, which attract each other, building up an ordered, periodical structure.
Covalent bond
Sharing of a couple of electrons. The shared electrons stay exactly in the middle of the two atoms. The electrons act as a «glue» (bonding electrons)
Polar Covalent bond
When atoms are not identical and non metals a covalent bond occurs which has unequal “pull” towards atom with the greater electron withdrawing capability. So positive charge on one
atom and a partial negative charge on the other. The two partial charges are equal in value, but opposite in sign, which results in a contribution of electrostatic attraction between the two atoms
Electronegativity
Tendency for an atom of a given chemical element to attract the shared
electrons in a chemical bond. If difference is 0 = covalent, if > 2 = ionic, if < 2 = polar covalent
Molecule
A group of two or more atoms, united each other with covalent or polar covalent bonds
Chemical compound
Microscopic definition: a pure substance formed by two or more atoms, chemically different, occurring with well-defined proportion in any point of the substance.
Macroscopic definition: a pure substance formed by two, or more, different chemical elements, with a defined proportion determining composition
can be covalent, polar, or ionic
