Lect. 1-3 Flashcards
Mixture
Contains particles or units of more than 1 specific atom or molecule i.e. solutions
Democritus
Atoms “atomos”
Antoine Lavoisier
Law of conservation of mass
Joseph Proust
Law of Definite Proportions: i.e. water is always 88.8% oxygen and 11.2% hydrogen
John Dalton
First guy with an atomic theory
Dalton’s 4 postulates:
- Each element is composed of tiny particles called atoms
- All atoms of a given element are identical, and all atoms of different elements are different
- Atoms are not created or destroyed in a chemical reaction, they are dissociated, combined, or recombined
- Compounds are formed when atoms of different elements combine with one another. A given compound always contains the same relative numbers and types of atoms
J.J. Thompson
Electrons: stream of particles through electric field
Earnest Rutherford
Nucleus, gold foil experiment
Mass number
Protons+neutrons: upper left hand corner
Atomic number
Number of protons: bottom left hand corner
Isotopes
Same element, but with different number of neutrons
The 2 types of pure samples are…
Elements and compounds
Mass Spectrometry
- used to compare masses of isotopes
- atoms from a pure sample of an element are ionized (electrons stripped) and sent through a magnetic field
- isotopes with smaller masses are deflected more
Average atomic mass
(Mass#%)+(mass#%)+…
Mass %
}[(# of atoms of specific element)(elements atomic mass)]/(formula weight of compound)}*100
Law of Multiple Proportions
2 compounds made of the same 2 elements, the masses of the elements in each compound are small whole number ratios
Mass ratio of elements in a pure sample of a compound (constant composition)
The ratio of isotopes of a certain element in any pure sample of a given compound is constant
Wavelength, frequency, speed of light formula
c=λν
Purple light
High frequency, high energy, small wavelength
Red light
Low frequency, low energy, long wavelength
Max Planck
Quantum theory
Quantum theory
Energy increases and decreases in discreet units: by a full quantum or not at all
Quantum theory/Planks constant Equation
E=hv
E-energy per quantum
H-plancks constant
V-frequency
Photoelectric effect
- high intensity, low frequency light won’t eject electrons no matter what
- when threshold frequency is met, electrons are ejected immediately
- increasing intensity of light will increase ejection rate, but not velocity
- increasing frequency of light increases velocity of electrons
Einsteins theory
- a beam of light is a stream of particles called photons
- energy of a photon is related to its frequency by e=hv
- the quantum of Planck is a particle(photon)
- if the frequency of an electron is below a certain threshold, no electrons are ejected
- if the frequency of the photon is at or above a certain threshold, it’s energy is transferred to the electron
Bohr Model
Forces of attraction between electrons and nucleus result from opposite charges
Shells
Electrons in shells have quantized energy levels
Shielding effect
Electrons further away from nucleus are shielded by closer electrons
Coulomb’s law
Closer to nucleus=stronger attraction F=k(q1q2/d2) F-force of attraction K-constant Q-magnitude of charge associated with a particle - protons or electrons D-distance between charged particles
First ionization energy
-minimum amount of energy required to remove the outermost, least tightly held electron
Shell organization
SPDF
Orbital
Graphic representation of the space an electron will occupy 90% of the time
Quantum Mechanical Model
Solves the problem of subshells
Periodicity
Predictable trends on the table
