Transcript No Slide Title

THE VARIATION
OF ATOMIC
PROPERTIES
•
•
•
•
Charina Cameron
Jenn Lau
Stephanie Coldwell
Lyndsay Vidito
Atomic Radius
• The
size
of the atom.
First Ionization Energy
• First ionization energy is the energy
required to remove an electron from
an atom.
NOTE: Electronegativity is "...the ability of
an atom in a molecule to attract shared
electrons to itself." (Zumdahl, 1995,
Chemical Principles, p. 571)
PROCEDURE "A" QUESTIONS
1) How does the portion of the graph for elements 3 to 10
compare with the portion of the graph for elements 11 to 18?
• The pattern is the same. The trend
is that you are always starting at a
peak and then diminishing in
radius inversely. The portion from
11 to 18 is higher up in atomic
radius but follows the same trend
in decreasing in atomic radius as
the atomic number increases.
PROCEDURE "A" QUESTIONS
2) How does the portion of the graph for elements 19 to 36
compare with the portion of the graph for elements 11 to 18?
• There are approximately twice as
many elements and the comparison
is between the third and forth period
elements. The expected peak (if the
pattern repeated) at element 25 or 26
does not occur because this is the
middle of the transition elements.
Elements in the middle of a period
have a smaller atomic radius than
the ones at the beginning (group IA).
PROCEDURE "A" QUESTIONS
3) If the data for the transition metals were missing and the data for
elements 20 and 31 were joined directly with a broken line, how
would the portion of the graph for elements 19 to 36 then compare
with the portion of the graph for elements 11 to 18?
removed
• The portions would be almost
identical but the atomic radius
numbers would be higher so the
curve would be shifted higher.
The transition elements are
numerous and have smaller
atomic radius than the Alkali
metals.
PROCEDURE "A" QUESTIONS
4) If there is a periodic variation (i.e., regular repetition) between
atomic radii and atomic numbers of the elements, how would you
describe it?
• For any period, the atomic
radius is highest for its alkali
metal and decreases
gradually until it is smallest
for the noble gas in that
period. Also, as you go down
a group, the atomic radius
increases.
PROCEDURE "A" QUESTIONS
5) How does the portion of the graph for elements 3 to 10
compare with the portion of the graph for elements 11 to 18?
• The pattern is the same, but the overall
trend is slightly lower. This means that
less ionization energy is needed to
remove the valence electrons from the
elements of period three than from
period two. The trend is that more
ionization energy is required to remove
valence electrons from the noble gases
than from the elements in the beginning
of the rows. This is why noble gases are
so inert.
PROCEDURE "A" QUESTIONS
6) How does the portion of the graph for elements 19 to 36
compare with the portion of the graph for elements 11 to 18?
• Overall the ionization energies are
lower. They are highest for the
inert gases and lowest for the left
side of the periods. However,
from 19 to 36, 10 transition
elements are inserted which
extend the flat part of the curve in
the middle of the period where
ionization energies are lower.
PROCEDURE "A" QUESTIONS
7) If the data for the transition metals were missing and the data for
elements 20 and 31 were joined directly with a broken line, how
would the portion of the graph for elements 19 to 36 then compare
with the portion of the graph for elements 11 to 18?
• The portions remaining would be
almost identical but the ionization
energies would be shifted to
lower levels. Groups IIIA to
VIIIA would have a similar
ionization energy pattern. The
transition elements inserted
between groups IIA and IIIA are
numerous (10) and have lower
ionization energies so they flatten
and lengthen the curve.
removed
PROCEDURE "A" QUESTIONS
8) If there is a periodic variation between first ionization energy and
atomic numbers of the elements, how would you describe it?
• For any period, the first
ionization energy is highest
for the noble gas (Group
VIIIA) and lowest for the
alkali metals (Group IA).
The ionization energy then
increases from the alkali
metals to the noble gases in a
period.
CONCLUDING QUESTIONS:
1) What do you estimate to be the missing value of the
atomic radius of manganese? Of selenium?
• We estimated that the atomic radius of
manganese was about 0.12 nm. On the Alchem
periodic table of the elements, the atomic radius
is given as 0.140 nm.
• For selenium, we estimated the atomic radius
to be 0.115 nm which is the same as what is
given on the periodic table.
CONCLUDING QUESTIONS:
2) What do you estimate to be the missing value for
the first ionization energy of manganese? Of
selenium?
• We estimated that the first ionization energy
of manganese was about 750 kJ/mol of atoms.
• For selenium, we estimated the first
ionization energy to be about 1100 kJ/mol of
atoms.
CONCLUDING QUESTIONS:
3) Would you expect the atomic radius to be larger or
smaller for element 37 than for element 36? Give the
reason for your answer.
•
We would expect that the atomic
radius for element 37 to be larger than
that of element 36. The trend is for the
elements at the beginning of the period
(Alkali metals, such as Rb) to have
bigger atomic radii than the elements at
the end (e.g., Kr). Therefore, the atomic
radii diminish as one goes to the right in
the periodic table.
CONCLUDING QUESTIONS:
4) What should be the approximate value for the first
ionization energy of element 37?
•
We would expect that the first
ionization energy should be about 400
kJ/mol of atoms for element 37. The
trend is for the elements at the beginning
of the period (Alkali metals, such as Rb)
to have lower first ionization energies
than the elements at the end (e.g., Kr).
Therefore, the first ionization energy
increases as one goes to the right in the
periodic table.
CONCLUDING QUESTIONS:
5) Which one of all the elements whose atomic numbers are larger
than 36 should have the largest first ionization energy, and what will
be the approximate value of its first ionization energy?
•
We would expect that the noble gases
would have the highest values for the
first ionization energies. Of the two inert
gases above element 36, we would expect
xenon to have a higher value because the
first ionization energy appears to
decrease as you go down a group. Since
element 36 has a value of 1351 kJ/mol of
atoms, we would expect element 54 to
have a value of about 200 less. We
predict a value around 1150 kJ/mol of
atoms for this element's first ionization
energy.
THE END