|
|
|
|
|
Several elements are considered endangered
because there is a risk of these elements
becoming unavailable for commercial uses in
the next 100 years. helium, zinc,
gallium, indium, and tellurium are included
in the list of these endangered elements.
|
66 Identify three
endangered elements listed in the
passage that are classified as
metals.
| Answer-->
zinc (Zn),
gallium (Ga), indium (In)
Not helium or tellurium |
67 Explain, in
terms of electrons, why gallium
and indium have similar chemical
properties.
| Answer-->
same number
of valence electrons
the
number of out shell
electrons are the same |
68 Compare the density of a
sample of helium at STP with the
density of a sample of tellurium
at STP.
| Answer-->
helium is less dense than
tellurium
Use table S,
|
69 Explain, in terms of
electron shells, why the atomic
radius of an atom of indium is
greater than the atomic radius
of an atom of gallium when both
atoms are in the ground state.
| Answer-->
In has 1 more occupied
electron shell than Ga.
(these electrons are located
further from the nucleus) |
|
Questions
70-73 e
|
|
|
|