Honors Chemistry Midterm Review

Density
Denisty = Mass / Volume
Matter
Anything that has mass and takes up space
Pure Substance
Matter with the same fixed composition and properties
Element
Simplest form of matter, composed of only one type of atom
Compound
A chemical combination of 2 or more elements in a fixed proportion
Organic
Carbon-based
Mixture
A combination of 2 or more substances in which the basic identity of each substance is not charged
Heterogenous
Not mixed the same throughout
Homogenous
Mixed the same throughout
Solute
What is being dissolved
Occurs in the lesser extent
Solvent
What is doing the dissolving
Occurs to the greater extent
Physical Change
A change in which the same substance is present before and after the change
Chemical Change
A rearrangement of atoms and/or molecules to form one or more new substances with new properties
Physical Property
A characteristic of matter that is exhibited without a change in identity
Chemical Property
A property that can only be observed when there is a change in the composition of a substance
Extensive Physical Property
Does depend on the amount of matter
Intensive Physical Property
Does not depend on the amount of matter present
Distillation
A technique used to separate liquids based on their boiling points
Fractional Crystallization
The separation of substances by their solubility
Bond
The force holding atoms together in a compound or molecule
Molecule
Two or more atoms bonded together
Compound
Two or more different atoms bonded together
Diatomic Elements
H O N Cl Br I F
Covalent Bond
Involves the sharing of electrons
Linus Pawling
Came up with electronegativity
Electronegativity
Attraction of an atom for a shared pair of electrons
Bond Axis
Line joining the nuclei of 2 bonded atoms in a molecule
Molecular Motion
Symmetric, Asymmetric, Bending, Rotating
VSEPR Theory
Valence Shell Electron Pair Repulsion
Predicts the 3D shape of molecules
Hybrid Orbitals
Equivalent orbitals formed from orbitals of different energies
Hybridization
The merging of 2 or more unlike orbitals to form an equal number of identical orbitals in an atom
Sigma Bonds
A bond formed by the direct or end to end overlap of atomic hybrid orbitals
Pi Bonds
Bond formed by the sideways overlap of P orbitals (Not hybridized)
Polyatomic ions
Atoms are covalently bonded but the molecule has an overall charge
Delocalized Electrons
Free to move easily from one atom to the next throughout the metal and don’t belong to any particular atom
Intermolecular Forces
Forces between molecules
Intramolecular Forces
Forces within a molecules
Dipole-Dipole Forces
Force of attraction between polar molecules
London Forces
At any given instant, the distribution of electrons may be unequal and the positive nucleus of 1 atom may be attracted to the electrons of another
Momentary Dipole
A temporary uneven distribution of electronic charge between an atom at any given instant
Vander Waal’s Forces
Collective name for all intermolecular Forces
Avogadro’s Number
6.02 x 10^23 = 1 mole of something
Molecular Formula
The actual formula for a compound
Empirical Formula
The lowest ratio of atoms in a compound
Einstein’s Theory of Matter and Energy
E = mc^2
Planck’s Quantum Theory
E = h(V shaped frequency thing)
Speed of Light
c = (Branch thingy for wavelength)(V shaped frequency thing)
Newtonian Mechanics
Describes the behavior of visible objects at ordinary velocities
Quantum Mechanics
Describes the behavior of very small objects at speeds near the speed of light
Heisenberg Uncertainty Principle
It is impossible to know both the exact position and momentum of an electron simultaneously
Orbital
Where electrons are located (clouds)
An orbital can hold 2 electrons
Sublevel
Contain all the orbitals of a given shape
Aufbau Principle
An electron occupies the lowest energy orbital that can receive it
Hund’s Rule
Electrons must occupy all of the given orbitals of a sublevel singularly before pairing begins
Octet Rule
An atom with 8 electrons in its outermost shell is considered stable
Doberiener
Noticed that Ca, Ba, and Sr all had similar properties and that the mass of Sr was about half-way between Ca and Ba
TRIADS
John Newlands
Law of Octaves
Table with 7 rows of 7
Mendeleev
Order of increasing mass with 7 in the first two rows and 17 after that
Henry Moseley
Made table in order of atomic number