Download This activity will make use of the following website

This activity will make use of the following website:
http://acswebcontent.acs.org/games/pt.html
Below are general directions for using this interactive website.
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We will be using the plot data tab on the top of the periodic table. Click on that tab, and
you will be re-directed to a graphing screen, with a periodic table on the bottom.
Clicking on the properties tab results in a drop down screen, where you can change the
property being graphed. Notice that the graph plots the property on the y-axis, and
atomic number (Z) on the x-axis.
Clicking on an element from the PT below the graph, shows where that element is
plotted on the graph. You can also move your mouse across the graph, to highlight
specific elements.
You will use the groups tab, to highlight elements in the same group on the graph.
To clear the graph of group data, just click between the periodic table / electron
configuration / plot data tabs.
Clicking on the red element data box brings up a small box of element information.
Using the website graphs to guide you in understanding why the properties of atomic radius,
electronegativity, and first ionization energy change predictably through the periodic table.
As you explain why these properties change predictably, use the following key ideas in your
explanations:
 The number of protons in the atom’s nucleus
 The number of electrons in the atom
 Where the electrons are located among the energy levels
(valence vs. “core” electrons)
 How the nucleus can be “shielded” by core electrons
Refer back to these ideas, every time you have to
explain why a property changes!
Part 1. Atomic Radius
1. Atomic radius is one-half of the distance between the nuclei of two atoms of the same element
when the atoms are joined.
Measure the atomic radius of the bromine atom in Br2 shown here.
Use a ruler, and measure in cm.
Atomic radius of bromine: ______________
2. Examining the radius graph from the website, identify the trends in atomic radius:
answer will be increases or decreases or remains the same
Across a period, left  right:
___________________________________
Down a group, top  bottom: ___________________________________
Going across a period, from element to element on the PT,
atomic property
increasing / decreasing /
the same
the number of protons is________
the number of electrons is ________
the valence electrons are filling in ________ energy levels
Going down a group on the PT,
atomic property
increasing / decreasing /
the same
the number of protons is________
the number of electrons is ________
the valence electrons are filling in ________ energy levels
Explanation time!
Since different patterns exist across and down on the PT, there must be
atomic properties that experience different changes, going across versus going down. Explain how
electrons and protons are affecting the property of atomic radius, both down a group and across a
period in the PT.
Part 2. First Ionization Energy
1. First ionization energy is the energy required to remove the first electron from an atom.
2. Examining the first I.E. graph from the website, identify the trends in first ionization energy:
Across a period, left  right:
___________________________________
Down a group, top  bottom: ___________________________________
Going across a period, from element to element on the PT,
atomic property
increasing / decreasing /
the same
the number of protons is________
the number of electrons is ________
the valence electrons are filling in ________ energy levels
Going down a group on the PT,
atomic property
increasing / decreasing /
the same
the number of protons is________
the number of electrons is ________
the valence electrons are filling in ________ energy levels
Explanation time!
Since different patterns exist across and down on the PT, there must be
atomic properties that experience different changes, going across versus going down. Explain how
electrons and protons are affecting the property of first ionization energy, both down a group and
across a period in the PT.
Part 3. Electronegativity
1. Electronegativity is defined as the ability of an atom of an element to attract electrons when the
atom is in a compound.
2. Examining the electronegativity graph from the website, identify the trends in electronegativity:
Across a period, left  right:
___________________________________
Down a group, top  bottom: ___________________________________
Going across a period, from element to element on the PT,
atomic property
increasing / decreasing /
the same
the number of protons is________
the number of electrons is ________
the valence electrons are filling in ________ energy levels
Going down a group on the PT,
atomic property
increasing / decreasing /
the same
the number of protons is________
the number of electrons is ________
the valence electrons are filling in ________ energy levels
Explanation time!
Since different patterns exist across and down on the PT, there must be
atomic properties that experience different changes, going across versus going down. Explain how
electrons and protons are affecting the property of electronegativity, both down a group and across a
period in the PT.
Analysis Questions for Periodic Trends Activity
Names: ___________________________ , ___________________________
1. Which property of a nucleus, is most responsible for producing a high electronegativity value?
2. How can this property increase among elements down a group, yet electronegativity
decreases? Don’t just answer with a single word…explain clearly for full credit.
3. One way to define atomic radius, is to say that the atomic radius is the average distance that the
furthest electron in an atom can be found, away from the nucleus. If, going from element to
element across a period, the valence electrons (which are the furthest electrons from the nucleus)
are being added to the same energy level, then why doesn’t the atomic radius remain constant for
elements across a period? Explain clearly.
4. Define second ionization energy.
5. Why is there a huge jump between the first and second ionization energies for Sodium, but only a
small jump for Calcium?
6. True or false: A greater number of protons in the nucleus of an atom, guarantees a stronger hold
(attractive force) on valence electrons.
7. An ionic bond between two atoms forms when a valence electron from one atom, is transferred to
the other atom. Based on what you learned, which two atoms on the periodic table would require
the least amount of energy to form an ionic bond? This bond would also be the strongest, as it
would require the greatest amount of energy to return the electron.