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Atomic Mass vs Atomic Number
300
Potassium
250
Sodium
200
Atomic Mass
Lithium
150
Bromine
Chlorine
100
Fluorine
Krypton
Argon
50
Neon
Helium
0
0
5
10
15
20
25
30
35
40
Atomic Number
Ionization Energy vs Atomic Number
Helium
2500
Neon
2000
Ionization Energy
Fluorine
Argon
1500
Krypton
Chlorine
Bromine
1000
500
Lithium
Sodium
Potassium
0
0
5
10
15
20
Atomic Number
25
30
35
40
Electronegativity vs Atomic Number
4.5
Fluorine
Electronegativity (Pauling Scale)
4
3.5
Chlorine
Bromine
3
2.5
2
1.5
Lithium
Potassium
1
Sodium
0.5
Helium
Argon
Neon
Krypton
0
0
5
10
15
20
Atomic Number
25
30
35
40
ANALYSIS QUESTIONS:
1. Based on your graphs, what is the trend in atomic radius across a period? Down a family?
The noble gas family elements have the lowest atomic radii. The halogens family elements have
the second-lowest atomic radii. The alkali metal family elements have the highest atomic radii.
The farther to the left of a period an element is, the higher its atomic radius will be.
2. Based on your graphs, what is the trend in ionization energy across a period? Down a
family?
The alkali family elements have the lowest ionization. The halogen family elements have the
second-highest ionization, and the noble gas family elements have the highest ionization.
The farther to the left of a period an element is, the lower the ionization will be.
3. Based on your graphs, what is the trend in electronegativity across a period? Down a
family?
The noble gas family has the lowest electronegativity. The alkali family elements have the
second highest electronegativity, and the halogen family elements the highest. The
electronegativity is lowest towards both ends of a period, and higher in the middle.
4a) What is happening to the number of protons and the number of energy levels as you
move across the periodic table from left to right? How and why does this affect atomic
radius.
As you move across the periodic table, the atomic radius decreases. Electrons are being
added to the same energy level, but at the same time, protons are being added to the
nucleus. This creates a higher effective nuclear charge, which means that the force of
attraction pulling the electrons to the nucleus is stronger, resulting in a smaller atomic
radius.
b) What happens to the number of energy levels as you move down a column on the
periodic table. How and why does this effect ionization energy?
As you move down the periodic table, ionization energy decreases. Electrons become
further from the nucleus which makes it easier to remove the outermost one. The inner
electrons in elements with lower energy levels block the proton’s force of attraction
toward the nucleus, so it’s easier to remove the outer electrons.
c) What happens to the effective nuclear charge as you move across a period on the
periodic table? How does this effect ionization energy and electronegativity?
As you move across the period table (left to right) the nuclear charge increases. With
increased nuclear charge, you also get increased attraction that the atom has for electrons
in it’s outer shell, which means increased electronegativity. Ionization energy will decrease
because the attraction to the nucleus will decrease.
5a) Which group contains elements which are easiest to ionize? Explain why this is the
case.
The alkali family is the easiest to ionize because these elements have the least amount of ionization
energy. That means their valence electrons can be taken easily. The atoms of these elements are
relatively large and have their outer electrons farther away from the nucleus, making it easier for
them to lose electrons and form positive ions.
b) Explain why the third ionization energy of Ca would be much higher than the 1st and
2nd ionization energy Ca.
The third ionization energy of Ca would be much higher than the first and second because it becomes
progressively more difficult to remove electrons. An atom of calcium will be less willing to let go of its
third valence electron that its first and second. Removing a negative electron from a positive calcium ion
is more difficult that removing a negative electron from a regular calcium atom.
6. Which element would have the highest electronegativity in each set below? Explain why
this is.
a) Ca, Be or Mg
b) B, Li, or F
a.) Beryllium would have the highest electronegativity because it’s smaller than the other two,
and therefore its nucleus is closer to the surface and can take electrons far more easily than the
other two elements.
b.) Fluorine would have the highest electronegativity in this set, and it’s actually the element
with the highest electronegativity out of all the elements, and in general, elements in the
halogen element group have high electronegative values.
7. Write (or type) the electron configuration of each atom (high-light the valence electrons)
and its corresponding ion below each sketch (atomic radii are given in angstroms (1 x 10 -10 M).
8. Over the blank periodic table provided, write or type the number of valence electrons and the
expected ion charge for the transition metal block and for the families to the left and right of the
transitions metals (the alkali metals have been done as an example).
Note: Carbon and boron do not normally form ions and are thus blanked-out