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Who was Ernest Rutherford?
- Discovered Alpha and Beta articles (used Alpha articles to probe the atom)
- Did the Gold foil exeriment
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What were the conclusions of the gold foil experiment?
- Matter is mainly empty space
- Matter contains small, massive, positive parts
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What did Rutherford's model look like?
- Small, massive, positive nucleus
- Electrons orbit nucleus
- Charges cancel (neutral)
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What were some problems with Rutherford's model?
- Could not explain why electrons stay outside nucleus
- Could not explain why electrons do not give off energy continuously
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Who was Max Planck?
Proposed matter has a property of waves
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What did Planck's wave property say?
It absorbs and radiates energy in bundles called quanta or photons
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What does electromagnetic radiation travel in?
Waves
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How fast do electromagnetic radiation waves travel (speed of light)?
3.0 * 108 m/s
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Distance between peaks
wavelength
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number of pulses per second
frequency
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height above midpoint
amplitude
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How are wavelength and frequency related?
Inversely (As one gets bigger, the other gets smaller)
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What is the wave equation?
c=λν
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In the wave equation c=λν, what is c?
Speed of light
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In the wave equation c=λν, what is λ?
Wavelength (in meters)
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In the wave equation c=λν, what is ν?
Frequency (in hertz)
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Which has a high frequency and which has a low frequency? Red and blue?
- Red - low frequency and long wavelength
- Blue - high frequency and short wavelength
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What color light contains all colors and is separated by a prism because its light refracts?
white
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What is the light energy equation?
E=hν
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In the light energy equation E=hν, what is h?
Planck's constant - 6.6 * 10-34 J/Hz
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In the light energy equation E=hν, what is ν?
Frequency (in hertz)
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What does it mean that light has a dual nature?
Particles and waves
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What are two things about light particles?
- Quanta or protons
- Have discreet amounts of energy
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What do quanta refer to?
waves
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What to photons refer to?
particles
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What did Neils Bohr do?
- Proposed atom model based on quanta
- Said that electrons could only possess, gain, and lose certain energies
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What did Bohr's model look like?
- Small massive positive nucleus
- Electrons orbiting nucleus in specific energy levels
- So, charges cancel making it neutral
- Had limits on number of electrons in energy levels
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What is the equation for the electrons able to fit in the energy levels of Bohr's model?
- 2*n21st - 2
- 2nd- 8
- 3rd - 18
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Electron position where electrons are close to the nucleus as possible
ground state
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Electron position where electron gains energy and jumps to a higher energy level
excited state
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Electron gives off energy (photon) and falls to a lower energy level
- De-excitation
- *This process produces emission (bright-line) spectra
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A the number of electrons increases, the emission spectrum becomes more ______
complex
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Each element has a _____ emission spectrum (like a _______)
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What an the emission spectrum be used for?
identifying elements
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When it came to emission spectras with Bohr's model what happened?
- It explained the emission spectrum for hydrogen very well
- It could not explain emission spectra of other elements
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What are elements composed of?
atoms
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Atoms combine in fixed whole number ratios to form what?
compounds
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Atoms are composed of what?
electrons circling a nucleus
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Nuclei are composed of what?
Protons and neutrons
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What is an atom with a different number of neutrons?
isotope
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What are protons and neutrons composed of?
quarks
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What are the fundamental particles?
electrons and quarks
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What is included in the modern atomic theory?
- Elements are composed of atoms
- Atoms combine in fixed whole number ratios to form compounds
- Atoms are composed of electrons circling a nucleus
- Nuclei are composed of protons and neutrons
- Not all atoms of an element are alike, some have different numbers of neutrons - isotopes
- Protons and neutrons are composed of quarks
- Electrons and quarks are the fundamental particles
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Number of protons
atomic number
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Number of neutrons
neutron number
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number of protons and neutrons
mass number
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Symbol to represent atomic number
Z
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Symbol to represent neutron number
N
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Symbol to represent mass number
A
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The weighted average mass of the naturally occuring isotopes of an element
atomic mass
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Why does A=Z+N?
Because the mass number equals the atomic number and the neutron number combined
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Atoms of an element with different numbers of neutrons
isotope
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Isotopes of an element have the same number of ______
protons
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What does the isotopic symbol look like?
ZAX
- A= number of protons and neutrons
- Z= number of protons
- X= chemical symbol
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What does Heisenberg's uncertainty principle state?
You cannot precisely know the position and momentum (velocity) of a subatomic particles
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What were some implications of Heisenberg's uncertainty principle?
- Bohr's model was wrong (no precise orbits)
- Electrons have wave properties
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What did the wave-mechanical model look like?
Electrons live where standing waves do not interfere negitively
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What did the electron areas in the wave-mechanical model look like?
Areas described by clouds with thickest density representing the most likely position
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A region of space around a nucleus that can contain electrons of nearly equal energies
energy level
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Where are the lowest energy electrons located?
closest to the nucleus
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A region of space within an energy level that can contain electrons with almost the same energies
sublevel
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What does the number of sublevels equal?
The energy level number
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What is the letter order of the sublevels?
S, P, D, F
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A region of space within a sublevel that can contaion at most two electrons with exactly equal energies
orbital
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What are the chances of finding an electron in an orbital?
90%
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How many orbitals does each sublevel (S, P, D, F) have?
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A place where electrons are not likely to be
node
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How many quantum numbers are there?
Four
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In quantum numbers, what is the principal number?
positive integer
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What does a principle number describe?
The energy level
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What is the symbol for the principal number?
n
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What is the orbital number?
0 or a positive integer up to n-1
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What is the orbital number also called?
azimuthal number
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What is the symbol of an orbital number?
l
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What does an orbital number describe?
The geometric shape of the orbital
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What shapes do the orbital numbers 0-3 have?
- 0 - sphere
- 1 - dumbell
- 2 - clover
- 3 - jacks
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What is the magnetic number?
Positive or negative integer from -l to +l
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What is the symbol for the magnetic number?
ml
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What does the magnetic number describe?
The oreintation of the orbital
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What is the spin number?
-1/2 or +1/2
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What is the symbol for the spin number?
ms
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What is the spin number associated with?
magnetic field
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A pair of electrons with opposite fields _____
- cancel
- They can stay in the same orbital
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No set of electrons in an atom can have the same _______
set of four quantum numbers
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Arrangement of electrons in an atom (written for ground state only)
electron configuration
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Uses boxes to represent orbitals of an occupied sublevel in an atom
orbital diagram (where electrons are shown as arrows)
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Uses sublevel ID and a superscript to show electron arrangement in sublevels
SPDF Notation
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The part of an electron configuration that is common to all elements in a period
Kernel notation
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Elements that have indomplete D sublevels and have abnormal electron configurations
anomalous configurations
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The outermost energy level contaioning electrons in the ground state
valence shell
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electrons in the valence shell
valence electrons
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What do valence electrons determine?
- Most chemical proerties
- Elements with the same number of valence electrons tend to react similarly
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Which group of valence shells are unreactive and why?
8, because they are full
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Show element symbol and uses dots on the sides
Lewis dot symbol
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Same valence shell
period
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Same number of valence electrons
groups
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Percentage of a given isotope in a very large sample of an element as it occurs on earth
natural abundance
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The actual mass of an atom
isotopic mass
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How is isotopic mass found?
By summing the masses of the nucleons
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A principle stating no two elecrons have the same sets of four quantum numbers
Pauli Exclusion Principle
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Calculated the strength of the forces between charged objects and found that if they are close they are strong and if they are far they are weak
Charles Coulomb
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Made the law of conservation of matter ( matter is concrete and measurable)
Antoine Lavoisier
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Formed the first Atomic Theory
John Dalton
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Showed cathode ray particles had negativve charges and proosed that these electrons are a fundamental part of all matter
J.J. Thomson
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