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Chem Test #2
Terms in this set (61)
Gives RELATIVE # of atoms of each element in a compound. Simplist ratio.
Gives ACTUAL # of atoms of each element in a molecule of compound.
Sketch/Diagram of how atoms in molecule are bonded to each other.
Ways of representing a compound
Lewis Dot Structure
Depicts the structural formula; focus on valence electrons b/c chemical bonding involves the transfer or sharing of valence electrons between two or more atoms.
Caused when atoms bonds, ten to gain, lose, share e- .
What MUST OBEY octet rule
nonmetal period 2 elements
Exceptions to the Octet Rule:
Involve the nonmetal elements located in period 3. Nonmetals (period 3) follow octet rule when they aren't center atom. When they are the center atom, they can accommodate more than eight electrons. Using empty valence d orbitals that are predicted by quantum theory. (22)
Like charges repel and opposite charges attract
Extra energy released from formation of a structure where cation is surrounded by anions vice versa. CL held together by electrostatic attraction of cations for all surrounding anions.=Stability
Ionization energy of metal. Sometimes Covalent
Electron Affinity of nonmetal. ALWAYS IONIC.
Extra stability accompanying the formation of crystal lattice. ALWAYS EXOTHERMIC. Depends on size of charges and inversely on dictate between ions.
Lewis Bonding Theory
Emphasizes valence electrons to explain bonding.
Predicts many properties of molecules: molecular stability, shape, size, & polarity. There is Ionic, Covalent, Metallic.
Cations + (metals) and Anions - (nonmetals)
Naming Ionic Compounds
1) State cation full name
2) State anion full name & replace suffix w/ -ide for monatomic.
3) For polyatomic, just state full name.
4) Transition metals cations, state charge with roman numerals.
-ate = 4,4,3
-ite = 3,3,2
ONLY W/ :
CL, BR, I
Per = +1
Hypo = -1
Memorize or Die
Carbonate = CO3^2-
Acetate = C2H3O2
Nitrate = NO3^1-
Nitrite = NO2^1-
Hydroxide = OH^1-
Ammonium = NH4^1+
Peroxide = 02^2-
Cyanide = CN^1-
Hydrated Ionic Compounds
Compound * #H20 = Name #hydrate
Ex: MgSO4*7H2O = Magnesium Sulfate Hepta-hydrate
Mono-1, Di-2, Tri-3, Tetra-4, Penta-5, Hexa-6, Hepta-7, Octa-8
Lewis Theory of Covalent Bonding
Some have stable combinations (octets) or not so much.
Naming Covalent Compounds
1) Just state name if it is singular.
2) Use prefixes for # of compounds & state name of 1st element. For 2nd element use -ide suffix. Mono-1, Di-2, Tri-3, Tetra-4, Penta-5, Hexi-6, Hepa-7, Octa-8
Organic Covalent Compounds
Main element is Carbon.
If sharing is unequal enough to produce a dipole in the bond is classified ass polar covalent. One end of the bond has larger electron density than other. The end w/ larger electron density gets partial
The end w/ electron-deficient gets a partial
Ability of an atom to attract bonding electrons to itself. Opposite of atomic size trend. The larger the difference in EN, the more polar the bond.
If the difference between bonded atoms is 0, the bond is pure covalent. Equal sharing of the atoms in the bond.
If the difference between bonded atoms is 0.1 to 0.4, the bond is nonpolar covalent.
If the difference between bonded atoms is 0.5 to 1.9, the bond is polar covalent. Unequal sharing of electrons between the atoms in the bond.
If the difference in electronegativity between bonded atoms is larger than or equal to 2.0, the bond is ionic.
Measure of bond polarity
Percent Ionic Character
% of a bond's measured dipole moment compared to what it would be if the electrons were completely transferred.
Nonmetals (2nd period elements) must OBEY octet rule
If lacking an Octet, form double / triple bonds to do so
Double - C,O,N,S,P
Triple - C,O,N,S
Used when two or more valid Lewis
structures can be drawn for the same compound.
Electron bookkeeping system that
allows us to discriminate between alternative Lewis
Resonance Hybrid Structure
Actual molecule is a combination of the resonance forms
Rules for Resonance Structures
MUST HAVE: Same connectivity, Same # of electrons, 2nd row elements have max. 8 electrons. 3rd row can expanded octet. Formal charges MUST total the same. FC= (#valence electrons - #bonds - #lone pairs)
odd electron species
Incomplete octet - Don't exist as a molecule.
Elements (specifically metalloids and H atom) tendency is not to have a complete octet
Molecules or ions w/ more than 8 electrons around
an atom. Involve nonmetal element in 3rd period / below.
Amount of energy, in the gaseous state, that it takes to break one mole of a bond in a compound. Bonds get weaker down columns and get stronger across the period.
Measuring the distance between the nuclei of bonded atoms. It decreases from left to right across a period. Increases down the column.
How much energy must be added into the bond to. break it in half.
Trends on Bond Energies
More electrons two atoms share, the stronger the covalent bond. Triple = Strong , Single = Weak; The shorter the covalent bond, the stronger the bond. (Depending on EN)
Determines properties: Shape, Bonding (Ionic, Covalent, Polar Covalent), and Skeletal arrangement. Electron groups around the central atom will be most stable when they are as far apart as possible.
Arrangement of bonded atoms in shape
less than 120 degrees
less than 109.5 degrees
Between axial and equatorial positions are less than 90 degrees
Betweenequatorial positions are 90 degrees
Electron Domain Geometry
Linear ,Trigonal Planar, Tetrahedral,
Trigonal Bypyramidal, Octaherdral.
Electron and Molecular Geometries
Mixing different types of orbitals in the valence shell to make a new set of degenerate orbitals
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