CHEM 121 FINAL EXAM | UPDATED QUESTIONS AND ANSWERS UPDATED .Buy Quality Materials!
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Course
CHEM 121
Institution
CHEM 121
CHEM 121 FINAL EXAM | UPDATED QUESTIONS AND ANSWERS UPDATED .Buy Quality Materials!
Resonance structure
one of the two or more equally valid electron dot structures of a molecule or polyatomic ion. (Not isomer because the atoms stay in the same spot)
It cannot move the atoms after the initia...
CHEM 121 FINAL EXAM | UPDATED QUESTIONS AND
ANSWERS UPDATED .Buy Quality Materials!
Resonance structure
one of the two or more equally valid electron dot structures of a molecule or polyatomic
ion. (Not isomer because the atoms stay in the same spot)
It cannot move the atoms after the initial structure, no mirroring either.
Lewis Structure Rules
-least electronegative is central atom
-hydrogen and halogens (F,Cl,Br, and I) occupy ends
-Complete octets of all outer atoms
-place extras on central atoms
Isomer
Compounds with the same formula but different structures. (not a resonance structure
because the atoms are in different spots)
hypervalent species
- The central atom in lewis's structure has an expanded octet. It has more than 8
valence electrons.
- Atoms with a possible extended octet: Al, Si, P, S, Cl, Ga, Ge, As, Se, Br, Kr, In, Sn,
Sb, Te, I, Xe, Tl, Pb, Bi, Po, At.
- Only expand the octet it it reduces the total formal charge
resonance hybrid
the actual structure of a molecule that is intermediate between two or more resonance
structures.
No lone pair in these
IS NOT A LEWIS STRUCTURE
curved arrow notation
Shows where the electrons go in different resonance structures.
formal charge
valence electrons - 1/2(bonding electrons) - nonbonding electrons = Formal charge
Assumes that all electrons in a bond are charges equally between species.
Oxidation State
Assumes that electrons go to the most electronegative atom in chemical species.
Oxidation State Rules
1. Elements in their elemental form are zero oxidation state (Ex. Na, He, O2, H2, N2,
P4, S8, O3 = 0 oxidation state).
2. Group 1 metals are +1, Group 2 metals are +2 in compounds.
3. Hydrogen is +1 when bonded to nonmetals and -1 when bonded to metals. (When H
is at the end of the formula its -1. E.g. LiH) (if H is at the start of he formula it gets +1,
e.g. HCl)
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