Laws and Theories Flashcards
Avogadro’s principle
A statement of the direct relationship between the moles of a gas and the volume of that gas.
Beer’s Law
The statement that the absorbance of a sample is the product of the absorptivity, optical path length, and same concentration; A=abc.
Boyle’s Law
The law that expresses the inverse relationship between the volume and the pressure of a gas (an increase in one tube causes a decrease in the other).
PV = constant
P1V1=P2V2
PV=K
V=K/P
Boyle’s Law only describes the relationship between P and V (Gas that obeys this law is an ideal gas).
Charles’ Law
The law that expresses the direct relationship between the temperature and volume of a gas.
P/V = constant
V1/T1 = V2/T2
V = constant x T
Volume of a fixed amount of gas at a constant pressure increases linearly with increasing temperature in Kelvins. Volume of a gas increases with increasing temperature.
Dalton’s Law of Partial Pressures
The law that the total pressure of a gas is the sum of the individual pressures of all the gasses in the mixture.
Hund’s Law
The rule that every orbit al in a sub-level must fill with 1 electron before a 2nd electron of opposite spin can be added to any orbital in that sub level.
Ideal Gas Law
The law that relates temperature, pressure, volume, and moles of gas; PV=nRT. *Higher temp, lower pressure.
Volume of a molecule is insignificant when compared to the volume of its container. All collisions are elastic. No forces of attraction exist between the molecules. Gas molecules do not take up space.
Kinetic Theory of Gases
- The volume of gas molecules is negligible compared to the volume of space in which they move.
- Gas molecules move in a straight line between frequent collisions with the walls of the container and themselves. Particles are in constant motion; the collisions of the particles with the walls of the container are the cause of the pressure exerted by the gas.
- All collisions are elastic, i.e no energy is lost.
- There are negligible forces acting between molecules.
- The average KE of the gas molecules is directly proportional to the temperature.
The kinetic theory describes the behavior of an ideal gas.
Pauli Exclusion Principle
The requirement that no two electrons in an atom have the same set of four quantum numbers.
Real Gases
Often do not behave like ideal gasses at high pressure or low temperature. Because real molecules take up space, the molar volume of a real gas is larger than predicted by the ideal gas law at high pressures.
Quantum Mechanical Model
Explains the manner in which electrons exist and behave in atoms. Helps to predict the properties of atoms that are directly related to the behavior of the electrons.
Diffraction
Light scattered from a regular array of points or lines. Ex: backside of CD or DVD.
Max Planck
Heated solid bodies to incandescence. Radiation profiles were not continuous. Hypothesis: Energy can be gained or lost only in integer multiples (n) of hv. v= frequency of light h= Planck's constant: 6.626x10^(-34) Jxs
Quantum Theory
Theory developed by Planck, of matter and energy based on the concept of quanta. It is the theoretical basis of modern physics that explains the nature and behavior of matter and energy on the atomic and subatomic level.
No two electrons can have the same four quantum numbers.
The energy and position of an atom cannot be determined simultaneously.
Lower energy orbitals are filled with electrons before higher energy orbitals.
Photoelectric Effect
Many metals emit electrons when a light shines of their surface.
Classical wave theory attributed this effect to the light energy being transferred to the electron.
If the wavelength of light is made shorter, or the light wave’s intensity made brighter, more electrons should be ejected.
Problem: min frequency required before electrons would be emitted, regardless of intensity, called threshold frequency. High freq light from dim source caused electron emission without lag time.
Rydberg’s Spectrum Analysis
Rydberg analyzed the spectrum of hydrogen and found that is could be described with an equation that involved an inverse square of integers. (1/lamda)=R((1/nf)^2-(1/ni)^2))
Bohr Model of the Atom
Nuclear model of the atom does not explain what structural changes occur when the atom gains or loses energy. He developed a model of the atom to explain how the structure of the atom changes when it undergoes energy transitions. Electrons travel in orbits that are at a fixed distance from the nucleus. Stationary states. Therefore, the energy of the electrons was proportional to the distance the orbit was from the nucleus. Electrons emit radiation(photon of light) when they jump from an orbit with lower energy.
Main idea: Energy of atom was quantized(atom could have only very specific amounts of energy) and that the amount of energy in the atom was related to the electron’s position in the atom.
Emission spectrum
A pattern of particular wavelengths of light are seen that are unique to that type of atom or molecule.
Average Kinetic Energy Formula
KE = (3/2)KT
K=1.381 x 10^(-23)J/K
Irregular Electron Configurations
Cr: [Ar]4s^(1) 3d^5 Cu: [Ar]4s^(1) 3d^10 Mo: [Kr]5s^(1) 4d^(5) Ru: [Kr]5s^(1) 4d^(7) Pd: [Kr]5s^(0) 4d^(10)
Periodic Table Trends
IE: decreases as you go down, and increases as you go right
AR: increases as you go down, and decreases as you go right
Electronegativity(measure of tendency of an atom to attract a bonding pair of electrons: decreases as you go down, increases as you go right
