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Chemistry: Lecture 1: Atoms, Molecules, and Quantum Mechanics


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What is the mass of a proton/neutron?
1 amu
Mass Number
A = protons + neutrons
Atomic Number
Z = protons
-Two or more atoms of the same element that contain different numbers of neutrons
-Isotopes have similar chemical properties
-Atomic Mass Unit
-One atom of carbon 12 has an atomic weight of 12 amu
-6.022*10^23 amu = 1 gram
6.022 * 10^23

-The number of carbon atoms in 12 grams of carbon 12
Horizontal rows
Vertical columns
-Form cations(+)
-Metallic character includes ductility, malleability, thermal and electrical conductivity, and a characteristic luster
-Typically form ionic oxides
-Form anions(-)
-Have lower melting points than metals
-Form covalent oxides
-Have some characteristics that resemble metals and some that resemble nonmetals
Elements in the same ________ on the periodic table have similar chemical properties(tend to make same # of bonds, similarly charged ions)
Group 1A
-Alkali Metals (form 1+ cations)
-Soft metallic solids with low densities and low melting points
-Highly reactive
-In nature, exist only in compounds
Group 2A
-Alkaline Earth Metals (form 2+ cations)
-Harder, more dense, and melt at higher temperatures than alkali metals
Group 5A
-Can form 3 covalent bonds
-All 5A elements except nitrogen can form five covalent bonds by using d orbitals
-Nitrogen(strong) and Phosphorus(weak) can form pi bonds
Group 6A(chalcogens)
-Includes oxygen and sulfur
-Second most electronegative element
-Divalent and can form strong pi bonds
-Can form 2,3,4, or even 6 bonds
-Has ability to make strong pi bonds
Group 7A(halogens)
-Highly reactive (like to gain e-)
-Fluorine always has oxidation state of -1, meaning it only makes one bond
Noble Gases
-All gases at room temperature
Small Atoms
-Bond strongly to water, resulting in greater heats of hydration
-Don't have d orbitals, so can't form more than 4 bonds
-Make strong pi bonds due to overlap of p orbitals
Large Atoms
-Have d orbitals allowing for more than 4 bonds
-Unable to make strong pi bonds
When the transition metals form ions, they lose electrons from their ____ subshell first, and then from their ____ subshell
How do atoms lose electrons?
Atoms lose electrons from the highest energy shell first
Isoelectric Ions
-Ions with the same number of electrons
-Tend to get smaller with increasing atomic #
Effective Nuclear Charge(Zeff)
-The amount of charge felt by the second electron (EX: in helium)
-Increases from left to right and top to bottom
Ionization Energy
-The energy necessary to detach an electron from a nucleas
-Increases from left to right and bottom to top
-Tendency of an atom to attract an electron in a bond that it shares w/ another atom
-Increases from left to right and bottom to top
Electron Affinity
-The willingness of an atom to accept an additional electron (energy that is released when an electron is added to a gaseous atom)
-Increases from left to right and bottom to top
Atomic Radius
-Increases from right to left and top to bottom
Metallic Character
-Increases from right to left and top to bottom
Bond Length
-Defined as the point where the energy level is the lowest
-A substance made from two or more elements in definite proportions
T or F: Energy is not always required to break a bond
T or F: No energy is ever released by breaking a bond
Crystalline Solids
-Sharp melting point, characteristic shape w/ a well ordered structure of repeating units (atoms, molecules, or ions)
-Can be ionic, network covalent, metallic, or molecular
Amorphous Solid
-Has no characteristic shape and melts over a temperature range (EX: glass)
-Solids w/ repeated structural units, and can be crystalline or amorphous
-Rapid cooling results in amorphous solids
-Slow cooling results in crystalline solids
First Quantum Number
-Designates the shell (n)
-Has the value (n)
Second Quantum Number
-Designates the subshell (l): s,p,d, and f
-Ranges from zero to n-1
Third Quantum Number
-Designates the orbital (ml)
-Ranges from l and -l
Fourth Quantum Number
-Designates the spin (ms)
-Ranges from 1/2 to -1/2
Heisenberg Uncertainty Principle
dx*dp = h
Hund's Rule
-Electrons will not fill any orbital in the same subshell until all orbitals in that subshell contain at least one electron, and the unpaired electrons will have parallel spins
Planck's Equation
dE = hf (f = frequency)
de Broglie Equation
wavelength = h/mv

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