SAT Subject Test in Chemistry › Periodic Trends
The following is a modified true/false question. In it, you must decide if each individual statement is true (T) or false (F). If both are true, then you must also decide if the second statement is a correct explanation (CE) of the first statement.
I: Atoms in the alkaline earth metal group have smaller ionic radii than their atomic radii
BECAUSE
II: atoms in this group usually lose electrons in order to become ions, resulting in the ion lacking the outermost energy level present in the atom.
T, T, CE
F, F
F, T
T, F
T, T (II is not a correct explanation of I)
The alkaline earth metals are the elements in group II, such as beryllium and magnesium. They want to have a complete octet in their outermost energy level, so they tend to lose two electrons to form the ionic state, which gives them the electron configuration of the noble gas in the previous energy level and thus a smaller ionic radius. Therefore, both statements are true and the second correctly explains the first.
The elements with the smallest atomic radii tend to be found in which part of the periodic table?
The upper right corner
The inner transition metals
The upper left corner
The bottom left corner
The bottom right corner
Atomic radius tends to increase down a group due to the addition of new energy levels; however, it decreases across a period due to increased shielding and increased nuclear mass. For these reasons, the elements with the smallest atomic radii would be in the upper right corner of the periodic table.