CHEM 220 INORGANIC CHEMISTRY MIDTERM
EXAM QUESTIONS AND CORRECT ANSWERS
GRADED A+ 2025
Trends in atomic radius in period 3
Atomic radius decreases from Na to Cl, nuclear charge increases, electrons are
added to the same shell so nuclear attraction increases pulling the shells in
Why can't atomic radius be measured for argon?
Argon exists as single atoms (monoatomic) and does not form any bonds
best electrical conductor
Aluminium as it has 3 delocalised electrons
Sodium flame colour
yellow
Magnesium flame colour
bright white
, Aluminium flame colour
white
Silicon flame colour
White
Phosphorus flame colour
White or yellow
Sulfur flame colour
Blue
how alkaline a solution will be depends on
the strength of the lattice - stronger lattices don't break easily. They decompose to
form less OH- ions. Since the conc of OH- is less, the pH is also less.
Proof of amphoteric nature of aluminium oxide
Al2O3 + 6HCl -> 2AlCl3 + 3H2O
Al2O3 + 2NaOH (+3H2O) -> 2NaAl(OH)4
EXAM QUESTIONS AND CORRECT ANSWERS
GRADED A+ 2025
Trends in atomic radius in period 3
Atomic radius decreases from Na to Cl, nuclear charge increases, electrons are
added to the same shell so nuclear attraction increases pulling the shells in
Why can't atomic radius be measured for argon?
Argon exists as single atoms (monoatomic) and does not form any bonds
best electrical conductor
Aluminium as it has 3 delocalised electrons
Sodium flame colour
yellow
Magnesium flame colour
bright white
, Aluminium flame colour
white
Silicon flame colour
White
Phosphorus flame colour
White or yellow
Sulfur flame colour
Blue
how alkaline a solution will be depends on
the strength of the lattice - stronger lattices don't break easily. They decompose to
form less OH- ions. Since the conc of OH- is less, the pH is also less.
Proof of amphoteric nature of aluminium oxide
Al2O3 + 6HCl -> 2AlCl3 + 3H2O
Al2O3 + 2NaOH (+3H2O) -> 2NaAl(OH)4
