South Pasadena • Chemistry
Name
Period
Date
9 · Atomic Structure
PERIODIC TRENDS
WORKSHEET
1. Consider the elements silicon (Si), phosphorous (P), and arsenic (As).
(a) Complete the following chart:
Silicon
Phosphorous
Short-Form Electron
Configuration
Arsenic
# of Protons
# of Layers of electrons
Atomic Radius (pm)
(b)
111
Ionization Energy
786.5
(kJ/mol)
Compare silicon with phosphorous.
98
114
1011
947.0
When we go from Si to P, we are moving [ across a period | down a family ].
There are
protons in Si and
protons in P.
Because P has [ more | the same number of | fewer ] protons as Si,
the outer electron in P feels [ a stronger | the same | a weaker ] attraction to the nucleus,
so P has [ a larger | the same | a smaller ] atomic radius than/as Si.
It requires [ more | the same | less ] energy to remove the outer electron in P (compared to Si),
so P has [a larger | the same | a smaller ] ionization energy and electronegativity than/as Si.
In general, as we move [ across a period | down a family ],
the atomic radius [ increases | remains the same | decreases ] and
the ionization energy and electronegativity [ increases | remains the same | decreases ].
(c)
Compare phosphorous with arsenic.
When we go from P to As, we are moving [ across a period | down a family ].
There are
layers of electrons in P and
layers of electrons in As.
Because As has [ more | the same number of | fewer ] layers of electrons as P,
The outer electron in As is [ further from | the same distance from | closer to ] the nucleus
and feels [ a stronger | the same | a weaker ] attraction to the nucleus,
so As has [ a larger | the same | a smaller ] atomic radius than/as P.
It requires [ more | the same | less ] energy to remove the outer electron in As (compared to P),
so As has [a larger | the same | a smaller ] ionization energy and electronegativity than/as P.
In general, as we move [ across a period | down a family ],
the atomic radius [ increases | remains the same | decreases ] and
the ionization energy and electronegativity [ increases | remains the same | decreases ].
2. Compare oxygen (O), fluorine (F), and chlorine (Cl). (Use this as a model for explanations.)
(a)
Between O and F,
has fewer protons than
, so the outer electron is [ more | less ] attracted to the nucleus.
Therefore, it has a [ larger | smaller ] atomic radius and [ higher | lower ] ionization energy.
(b)
Between F and Cl,
has fewer layers of electrons than
, so the outer electron is [ further from | closer to ]
and is [ more | less ] attracted to the nucleus.
Therefore, it has a [ larger | smaller ] atomic radius and [ higher | lower ] ionization energy.
3. Make the following comparisons and provide an explanation for each (using the model in question 2).
(a) Which has a larger atomic radius: cobalt (Co) or nickel (Ni)?
(b)
Which has a lower ionization energy: strontium (Sr) or barium (Ba)?
(c)
Which has a smaller atomic radius: antimony (Sb) or bismuth (Bi)?
(d)
Which has greater electronegativity: bromine (Br) or iodine (I)?
4. Compare the radii of the following.
(a) Ar vs. Ar+
Ar has [ more | the same | less ] protons and [ more | the same | less ] electrons than/as Ar+,
so it has [ more | the same | less ] repulsions with other electrons, and
and therefore a [ a larger | the same | a smaller ] radius than/as Ar+.
(b)
Ar vs. Ar–
Ar has [ more | the same | less ] protons and [ more | the same | less ] electrons than/as Ar–,
so it has [ more | the same | less ] repulsions with other electrons, and
and therefore a [ a larger | the same | a smaller ] radius than/as Ar–.
(c)
Ar vs. Cl– and K+
Ar, Cl–, and K+ have the same number of [ protons | electrons ]
but different numbers of [ protons | electrons ], listed in order:
<
<
Listed in order of increasing attractions to the nucleus:
<
<
.
Listed in order of increasing radius:
<
<
.
.