1. Atoms, Molecules, and Quantum Mechanics Flashcards
Moles (formula)
moles = grams / (atomic or molecular weight in g/mol)
Percent Yield
Percent yield = actual yield / theoretical yield
Planck’s Quantum Theory
delta E = hf (h is Planck’s constant 6.6 x 10^-4 Js) and f is frequency.
6.022x10^23
a mole. Avogradro’s number. 6.022x10^23 amu = 1 gram.
amu
“atomic mass units”. Used for atomic weight aka molar mass. An amu is defined by carbon-12. One atom of carbon-12 has an atomic weight of 12 amu. All other atomic weights are measured against this standard.
Avogradro’s Number
6.022x10^23. a mole.
Atomic Number
Denote as “Z”. Found bottom left of the element symbol. Number of protons. This is the identity of the element.
Atomic Radius
Distance from the center of the nucleus to the outermost electron. (aka, size of atom). LEFT to RIGHT: DECREASES. TOP to BOTTOM: INCREASES.
Atomic Weight
aka molar mass in units amu. Not weight.
Atoms
Tiny particles making up mass.
Bond Dissociation Energy
Energy needed to break the bond.
Bond Energy
The energy necessary to achieve a complete separation of two atoms so there are no more forces between the two atoms.
Bond Length
The point where the energy level is the lowest (bonds are only formed when two atoms can lower their overall energy level).
Bonds
Connects atoms.
Compounds
Made from two or more elements in definite proportions.
Covalent Bond
Two electrons are shared by two nuclei.
Effective Nuclear Charge (Zeff)
The amount of charge felt by the second electron due to shielding of the first electron. x LEFT to RIGHT: INCREASES, TOP to BOTTOM: INCREASES.
Electron Affinity
Willingness of an atom to accept an additional electron. Energy released when an electron is added. LEFT to RIGHT: INCREASES, TOP to BOTTOM: DECREASES.
Electronegativity
Tendency of an atom to attract these shared electrons. LEFT to RIGHT: INCREASES, TOP to BOTTOM: DECREASES.
Electron Configuration
Shells and subshells listed in order from lowest to highest energy level. 1s2s2p3s3p4s3d4p.
Electrons
Surrounds the nucleus of an atom. Weight nothing relative to proton or neutron.
Elements
Building blocks of all compounds and cannot be decomposed into simpler substances by chemical means.
Empirical Formula
Ratio for relative numer of atoms of one element to another. Simplified version of molecular formula.
First Ionization Energy
Energy to detach an electron from a neutral atom to form +1 cation.
Ground State
Atoms whose electrons are all at their lowest energy levels.
Groups or Families
Vertical columns of periodic table.
Hund’s Rule
Electrons prefers to have its own orbital when such an orbital is available at the same energy level. Definition: 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 to avoid repulsion of like charges.
Inert Gases
Noble gases (last family). Nonreactive. Gases at room temp.
Ionization Energy
Energy necessary to detach an electron from a nucleus. LEFT to RIGHT: INCREASES. TOP to BOTTOM: DECREASES
Isotopes
Same element (same number of protons) but different numbers of neutrons. Have similar chemical properties.
Mass Number
denote as “A”. Found top left of the element symbol. Number of protons plus neutrons.
Metallic Character
LEFT to RIGHT: DECREASES, TOP to BOTTOM: INCREASES
Metalloids
B, Si, GE, As, Sb, Te, At. Characteristics that resemble metals and nonmetals.
Metals
Left side of table and f-block. Large atoms, tend to lose electrons to form positive ions. Metallic characteristics: ductility (easily stretched), malleability (hammered into thin strips), thermal and electrical conductivity, luster. All metals but mercury are solids at room temp. Typically form ionic oxides (except BeO, not ionic).
Molar Mass (MM or M)
mass, not weight.
Mole (mole)
carbon-12 defines a mole. A mole is 6.022x10^23 of something.
Molecular Formula
Represents the exact number of elemental atoms in the molecule.
Molecules
Groups of atoms form repeated, separate and distinct units.
Nonmetals
Right of table. Generally have lower melting points than metals. Form negative ions. Form covalent oxides such as SiO2 or CO2.
Nucleus
Center of atom where you can find protons, neutrons.
Period
Horizontal row of periodic table.
Periodic Table
Lists the elements from left to right in the order of their atomic numbers.
Photoelectric Effect
Know that kinetic energy of the electrons increases only when the frequency is increased. One-to-one, photon to electron collision. Light was made up of particles.
Protons
Has positive charge. Resides in the nucleus of an atom.
Second Ionization Energy
Energy to remove second electron to form +2 cation. Always greater than the first because Zeff increased.
Shell
n. Principle quantum number. energy level.
Sheilding
In atoms with more than one electrons, the first electron shields some of the nuclear charge from the second electron and so it doesn’t feel the entire nuclear charge Z, just feels partial.
Subshells
l. azimuthal quantum number.
Transition Metals
d-block.
Valence Electrons
Electrons on the outermost shell and contribute to an element’s chemical properties.
Diatomic Molecules
H, O, N and halogens.
Pauli Exclusion Principle
No two electrons in the same atom can have the same four quantum numbers.
Principle Quantum Number (n)
Designates shell level.
Azimuthal Quantum Number (l)
Subshell, shape.. L = 0 is s. l = 1 is p. l = 2 is d. l = 3 is f.
Magnetic Quantum Number (ml)
Precise orbital of a given subshell. Range from -l to l.
Electron Spin Quantum Number (ms)
To distinguish the two electrons that may occupy the same orbital. Value are -1/2 and +1/2
Heisenberg Uncertainty Principle
keywords are “position and momentum”. The more we know about the momentun of any particle, the less we know about the position. The uncertainty is on the order of Planck’s constant (6.63 x 10^-34 Js, super small).
Aufbau Principle
With each new proton added to create a new element, the new electron that is also added will occupy the lowest energy level that is available to it. Lower the energy level, more stable the system.
