Please speak up if you believe your
answer is more correct than answers
listed below! Be sure that you can write electronic configurations
and understand trends is periodic properties.
20
From graph--estimate 23 g/cm^3. This gives 141 g/mol
24
As n increases, the number of electrons per shell increases according
to 2n^2.
Therefore each period does not have the same number of elements.
26
a 112
b 115
c 118
30
H+ < He < H < H-
Helium has +2 for the nuclear charge which contracts its electronic
orbitals.
H+ is the smallest because it only has a nucleus.
38
1.603 x 10^18 ions
44
a [Ar]3d8
b [Ar]3d9
c [Ar]3d3
each of these loses the 4s electrons.
50
a -75 degrees (very approximately)
b -71 degrees (but water is exceptional due to H bonding--to be
studied later)
52
a 1
b 1
c 3
d 4
e 2
f 2
60
Using the volume of a sphere, 4/3 pi r^3 we calculate16.3 cm^3/mol
(remember that 1 pm is 10^-12 m). The calculated volume is less
than the actual volume of 24 cm^3/mol because we have neglected
the empty spaces between spheres. Another opportunity to practice
those conversions!
62
5249 kJ/mol
Calculate the energy required to go from n=1 to n=infinity (ionized).
Z=2 for the Helium nucleus and you'll need Avogadro's number to
convert to moles.
This value agrees well with the actual value, because the Rydberg/Bohr
model works well for 1 electron atoms and ions.