CHEMISTRY Atomic Structure
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CHEMISTRY Atomic Structure
Who was Ernest Rutherford?
Discovered Alpha and Beta articles (used Alpha articles to probe the atom)
Did the Gold foil exeriment
What were the conclusions of the gold foil experiment?
Matter is mainly empty space
Matter contains small, massive, positive parts
What did Rutherford's model look like?
Small, massive, positive nucleus
Electrons orbit nucleus
Charges cancel (neutral)
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
Who was Max Planck?
Proposed matter has a property of waves
What did Planck's wave property say?
It absorbs and radiates energy in bundles called quanta or photons
What does electromagnetic radiation travel in?
How fast do electromagnetic radiation waves travel (speed of light)?
3.0 * 10
Distance between peaks
number of pulses per second
height above midpoint
How are wavelength and frequency related?
Inversely (As one gets bigger, the other gets smaller)
What is the wave equation?
In the wave equation c=λν, what is c?
Speed of light
In the wave equation c=λν, what is λ?
Wavelength (in meters)
In the wave equation c=λν, what is ν?
Frequency (in hertz)
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
What color light contains all colors and is separated by a prism because its light refracts?
What is the light energy equation?
In the light energy equation E=hν, what is h?
Planck's constant - 6.6 * 10
In the light energy equation E=hν, what is ν?
Frequency (in hertz)
What does it mean that light has a dual nature?
Particles and waves
What are two things about light particles?
Quanta or protons
Have discreet amounts of energy
What do quanta refer to?
What to photons refer to?
What did Neils Bohr do?
Proposed atom model based on quanta
Said that electrons could only possess, gain, and lose certain energies
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
What is the equation for the electrons able to fit in the energy levels of Bohr's model?
1st - 2
3rd - 18
Electron position where electrons are close to the nucleus as possible
Electron position where electron gains energy and jumps to a higher energy level
Electron gives off energy (photon) and falls to a lower energy level
*This process produces emission (bright-line) spectra
A the number of electrons increases, the emission spectrum becomes more ______
Each element has a _____ emission spectrum (like a _______)
What an the emission spectrum be used for?
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
What are elements composed of?
Atoms combine in fixed whole number ratios to form what?
Atoms are composed of what?
electrons circling a nucleus
Nuclei are composed of what?
Protons and neutrons
What is an atom with a different number of neutrons?
What are protons and neutrons composed of?
What are the fundamental particles?
electrons and quarks
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
Number of protons
Number of neutrons
number of protons and neutrons
Symbol to represent atomic number
Symbol to represent neutron number
Symbol to represent mass number
The weighted average mass of the naturally occuring isotopes of an element
Why does A=Z+N?
Because the mass number equals the atomic number and the neutron number combined
Atoms of an element with different numbers of neutrons
Isotopes of an element have the same number of ______
What does the isotopic symbol look like?
A= number of protons and neutrons
Z= number of protons
X= chemical symbol
What does Heisenberg's uncertainty principle state?
You cannot precisely know the position and momentum (velocity) of a subatomic particles
What were some implications of Heisenberg's uncertainty principle?
Bohr's model was wrong (no precise orbits)
Electrons have wave properties
What did the wave-mechanical model look like?
Electrons live where standing waves do not interfere negitively
What did the electron areas in the wave-mechanical model look like?
Areas described by clouds with thickest density representing the most likely position
A region of space around a nucleus that can contain electrons of nearly equal energies
Where are the lowest energy electrons located?
closest to the nucleus
A region of space within an energy level that can contain electrons with almost the same energies
What does the number of sublevels equal?
The energy level number
What is the letter order of the sublevels?
S, P, D, F
A region of space within a sublevel that can contaion at most two electrons with exactly equal energies
What are the chances of finding an electron in an orbital?
How many orbitals does each sublevel (S, P, D, F) have?
S - 1
P - 3
D - 5
F - 7
A place where electrons are not likely to be
How many quantum numbers are there?
In quantum numbers, what is the principal number?
What does a principle number describe?
The energy level
What is the symbol for the principal number?
What is the orbital number?
0 or a positive integer up to n-1
What is the orbital number also called?
What is the symbol of an orbital number?
What does an orbital number describe?
The geometric shape of the orbital
What shapes do the orbital numbers 0-3 have?
0 - sphere
1 - dumbell
2 - clover
3 - jacks
What is the magnetic number?
Positive or negative integer from -l to +l
What is the symbol for the magnetic number?
What does the magnetic number describe?
The oreintation of the orbital
What is the spin number?
-1/2 or +1/2
What is the symbol for the spin number?
What is the spin number associated with?
A pair of electrons with opposite fields _____
They can stay in the same orbital
No set of electrons in an atom can have the same _______
set of four quantum numbers
Arrangement of electrons in an atom (written for ground state only)
Uses boxes to represent orbitals of an occupied sublevel in an atom
orbital diagram (where electrons are shown as arrows)
Uses sublevel ID and a superscript to show electron arrangement in sublevels
The part of an electron configuration that is common to all elements in a period
Elements that have indomplete D sublevels and have abnormal electron configurations
The outermost energy level contaioning electrons in the ground state
electrons in the valence shell
What do valence electrons determine?
Most chemical proerties
Elements with the same number of valence electrons tend to react similarly
Which group of valence shells are unreactive and why?
8, because they are full
Show element symbol and uses dots on the sides
Lewis dot symbol
Same valence shell
Same number of valence electrons
Percentage of a given isotope in a very large sample of an element as it occurs on earth
The actual mass of an atom
How is isotopic mass found?
By summing the masses of the nucleons
A principle stating no two elecrons have the same sets of four quantum numbers
Pauli Exclusion Principle
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
Made the law of conservation of matter ( matter is concrete and measurable)
Formed the first Atomic Theory
Showed cathode ray particles had negativve charges and proosed that these electrons are a fundamental part of all matter