CHEM 101 LATEST EXAM PREP
QUESTIONS AND ANSWERS PDF 2026
▶ isotopes. Answer: Atoms with the same number of protons but different
numbers of neutrons
Properties determined by # of protons
▶ ions. Answer: atoms with a charge
-caused by different number of electrons
(-) = anion (electrons actually missing but taking away negative so # will go
up)
(+) = cation (CATion = PAWsitive) (electrons actually gained but is adding
a negative so # will go down)
▶ How many electrons in O^-2. Answer: 8
O two more e- = 10e-
16
▶ How many e- in sodium?. Answer: 11 <-- 11 protons, 11 electrons if
neutral
Na
22.99
Na has a +1 charge on periodic table, so = 10e-
▶ electron shells. Answer: n=3 18e-
n= 2 8e-
n = 1 2e-
go from bottom up
highest up shell = valence electrons
▶ ionic compounds. Answer: cations and anions (pos and neg)
written Cation Anion
, ex: write the formula for salt made of calcium + F
= Ca^+2 F^-1 so CaF2 (need to balance charges)
formed by metals + nonmetals
▶ ionic bond. Answer: between + and - charge
▶ covalent bond. Answer: between non metals
atom bonded to another atom of the same type
share electrons in order to get to 8 valence e- (except H and He get 2)
▶ naming covalent compounds. Answer: prefix: 1 mono, 2 di, 3 tri, 4 tetra,
5 penta, 6 hexa, 7 hepta, 8 octa, 9 nona, 10 deca
ending in "ide"
▶ transition metals. Answer: always + but some elements can have
multiple charges
▶ naming ionic compounds. Answer: (cation) (anion + ide)
NaCl = Sodium Chloride
Copper (II) Chloride = CuCl2
TiCl4 = Titanium (IV) Chloride
**transition metals usually have charge written as roman numeral
▶ common bonding patterns. Answer: hydrogen = 1 bond
carbon = 4 bonds
nitrogen = 3 bonds, 1 LP
oxygen = 2 bonds, 2 LP
Halogens = 1 bond, 3 LP
▶ when drawing lewis structures, the atom that can form the most bonds is
usually in the center. Answer: ex: CCl4 ---> the C is in the middle, the Cl
surround it
▶ Polyatomic ions. Answer: NH4+ = ammonium
OH- = hydroxide
NO3- = nitrate
NO2- = nitrite
HCO3- = bicarbonate
CN- = cyanide
QUESTIONS AND ANSWERS PDF 2026
▶ isotopes. Answer: Atoms with the same number of protons but different
numbers of neutrons
Properties determined by # of protons
▶ ions. Answer: atoms with a charge
-caused by different number of electrons
(-) = anion (electrons actually missing but taking away negative so # will go
up)
(+) = cation (CATion = PAWsitive) (electrons actually gained but is adding
a negative so # will go down)
▶ How many electrons in O^-2. Answer: 8
O two more e- = 10e-
16
▶ How many e- in sodium?. Answer: 11 <-- 11 protons, 11 electrons if
neutral
Na
22.99
Na has a +1 charge on periodic table, so = 10e-
▶ electron shells. Answer: n=3 18e-
n= 2 8e-
n = 1 2e-
go from bottom up
highest up shell = valence electrons
▶ ionic compounds. Answer: cations and anions (pos and neg)
written Cation Anion
, ex: write the formula for salt made of calcium + F
= Ca^+2 F^-1 so CaF2 (need to balance charges)
formed by metals + nonmetals
▶ ionic bond. Answer: between + and - charge
▶ covalent bond. Answer: between non metals
atom bonded to another atom of the same type
share electrons in order to get to 8 valence e- (except H and He get 2)
▶ naming covalent compounds. Answer: prefix: 1 mono, 2 di, 3 tri, 4 tetra,
5 penta, 6 hexa, 7 hepta, 8 octa, 9 nona, 10 deca
ending in "ide"
▶ transition metals. Answer: always + but some elements can have
multiple charges
▶ naming ionic compounds. Answer: (cation) (anion + ide)
NaCl = Sodium Chloride
Copper (II) Chloride = CuCl2
TiCl4 = Titanium (IV) Chloride
**transition metals usually have charge written as roman numeral
▶ common bonding patterns. Answer: hydrogen = 1 bond
carbon = 4 bonds
nitrogen = 3 bonds, 1 LP
oxygen = 2 bonds, 2 LP
Halogens = 1 bond, 3 LP
▶ when drawing lewis structures, the atom that can form the most bonds is
usually in the center. Answer: ex: CCl4 ---> the C is in the middle, the Cl
surround it
▶ Polyatomic ions. Answer: NH4+ = ammonium
OH- = hydroxide
NO3- = nitrate
NO2- = nitrite
HCO3- = bicarbonate
CN- = cyanide
