Atomic Theory & Structure Flashcards
Aristotle
Believed all nonliving matter was made up of four elements: Earth, wind, water, and fire
Democritus
Believed that matter was made of indivisible particles called atmos (where atoms term came from)
Dalton (1800s)
Proposed modern atomic theory
Modern atomic theory
- Matter is composed of atoms (true)
- Atoms of the same element are the same/atoms of different elements are different (doesn’t consider isotopes)
- Atoms can’t be subdivided, created, or destroyed (can be divided into protons, neutrons, etc)
- Atoms combine in chemical reactions to form compounds
JJ Thompson
Performed cathode ray experiments and discovered electrons. Developed Plum Pudding Model
Rutherford
Performed gold foil experiment and discovered the nucleus (proton)
Bohr
Developed “solar system” of the atom. Worked only for hydrogen atom (experimental flaw)
Wave Model
Electrons are in a cloud surrounding the nucleus
Characteristics of a Proton (Rutherford)
Positive charge. Found in nucleus. Mass of 1 AMU
AMU
Atomic mass unit, 1/12th of a carbon atom
Characteristics of a Neutron (Chadwick)
No charge. Found in nucleus. Mass of 1 AMU
Characteristics of a Electron (Thomson)
Negative charge. Found in clouds outside of nucleus. Mass of 0 AMU
Atomic Number
Tells number of protons in an atom. Determines the element
Atomic Mass
Number of protons and neutrons in the atom
Electron Number
Same as the protons since the atoms are neutral
Average Atomic Mass
Weighted average of the relative abundance of each isotope
Isotope
Element with same number of protons but differing neutrons
Formula for Atomic Mass
(%) times (mass) + (%) times (mass)
Graph of Mass Spec
Always read y axis as amount. Always read x axis as mass
Formula for electrons held (per orbital)
2n^2
Sublevel S
1 orbital, holds up to 2 electrons
Sublevel P
3 orbitals, holds up to 6 electrons
Sublevel D
5 orbitals, holds up to 10 electrons
Sublevel F
7 orbitals, holds up to 14 electrons
Aufau Principle
Electrons fill lower energy levels before filling higher energy levels
Hund’s Rule
Electrons in a sublevel will fill each orbital before pairing up
Pauli’s Exclusion Principle
Electrons in same orbital will have different spins
Frequency and Wavelength
inversely related (Low frequency, big wavelength)
Non-ionizing (nondamaging) Wavelengths
Radio, TV, Microwaves
Infrared
Visible
Ionizing Wavelengths
Ultraviolet Rays
X-Rays
Gamma (Nuclear Radiation)
Absorb (electrons)
Move from lower to higher energy levels
Emission (electrons)
Moves from higher to lower energy levels (light)
UV Transition
Transition down to n (energy level)= 1
Visible transition
Transition down to n=2
Infrared transition
Transition down to n=3, anything above n=3 is infrared
Spectrums
Converge at higher energy levels (energy levels aren’t evenly spaced)
Visible light spectrum
ROYGBIV (ROY is low energy, GBIV is higher energy)
E=hv
E= energy measured in joules (per photon)
h= Planck’s constant
v= frequency (hertz)
Planck’s Constant
6.626 x 10^-34
c= (wavelength) v
c= speed of light
wavelength= measured in meters
v= frequency
c= speed of light
3.00 x 10^8 m/s
