Name:_____________________________________________________________________________________________________________
Periodic Trends Discovery (Unit 4.6-4.7)
You already know the patterns of atomic number, atomic mass and valance electrons on the periodic table. Today, you
will learn how to use the periodic table to make predictions about atomic size, electronegativity, and ionization energies.
In this activity, you will look at a few periodic trends that can help you make those predictions. Knowing these trends will
help you tremendously when we talk about bonding in the next unit.
PART A
Directions: On the periodic table at the end of this packet, label the atomic number for each element in the first row
of its box. In the second row for each element’s box, label the number of principal energy levels.
1) What happens to the number of protons as you move from left to right across a period?
2) What happens to the number of energy levels as you move from left to right across a period?
3) What happens to the number of energy levels as you move down a group?
PART B
Directions: In the graph below, the element’s atomic number is plotted on the x axis and its atomic radius is plotted
on the y axis. On the periodic table at the end of this packet, label each element’s atomic radius in the third row of its
box.
Name:_____________________________________________________________________________________________________________
When answering the questions below, remember that atomic radius is the distance from the nucleus to the
outermost electron.
1) In general, what happens to the atomic radius as you go down a group on the periodic table?
2) Using your knowledge of the structure of the atom, explain the trend in atomic radius you identified in #1.
3) In general, what happens to the atomic radius as you move from left to right across a period?
4) Using your knowledge of Coulombic attraction strength, explain the trend in atomic radius you identified in #3.
PART C
Directions: In the graph below, the element’s atomic number is plotted on the x axis and its ionization energy is
plotted on the y axis. On the periodic table at the end of this packet, label each element’s ionization energy in the
fourth row of its box.
When answering the questions below, remember that ionization energy is the amount of energy required to remove a
valance electron from an atom.
1) In general, does it require more or less energy to remove a valance electron as you go down a group?
2) Using your knowledge of Coulombic attraction strength, explain the trend in ionization energy you identified in #1.
3) In general, does it require more or less energy to remove a valance electron as you move across a period?
4) Using your knowledge of Coulombic attraction strength, explain the trend in ionization energy you identified in #3.
Name:_____________________________________________________________________________________________________________
PART D
Directions: In the graph below, the element’s atomic number is plotted on the x axis and its electronegativity is
plotted on the y axis. On the periodic table at the end of this packet, label each element’s electronegativity in the fifth
row of its box.
When answering the questions below, remember that electronegativity is the ability of an atom’s nucleus to attract
an additional electron.
1) There is no data point for which group of elements? What do you think that means about these elements’ desire to
attract additional electrons?
2) In general, is an atom more or less likely to attract additional electrons as you go down a group?
3) Using your knowledge of Coulombic attraction strength, explain the trend in electronegativity you identified in #2.
4) In general, is an atom more or less likely to attract additional electrons as you move across a period?
5) Using your knowledge of Coulombic attraction strength, explain the trend in electronegativity you identified in #4.