Periodic Table Chemistry Example 2

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Example 2

medium
Arrange the following elements in order of increasing atomic radius: Na\text{Na}, Mg\text{Mg}, K\text{K}, Al\text{Al}.

Solution

  1. 1
    Atomic radius decreases across a period (left to right) due to increasing nuclear charge.
  2. 2
    Atomic radius increases down a group due to additional electron shells.
  3. 3
    Na, Mg, Al are in Period 3 (radius: Al < Mg < Na). K is in Period 4, Group 1.
  4. 4
    Order: Al < Mg < Na < K.

Answer

Al<Mg<Na<K\text{Al} < \text{Mg} < \text{Na} < \text{K}
Periodic trends in atomic radius follow two rules: radius decreases across a period and increases down a group. These trends result from the balance between nuclear charge and electron shielding.

About Periodic Table

A systematic arrangement of all known chemical elements organized by increasing atomic number into rows (periods) and columns (groups), where elements in the same group.

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More Periodic Table Examples

Example 1 easy

Using the periodic table, predict whether silicon (Si) is a metal, nonmetal, or metalloid. Justify y

Example 3 easy

Which group of the periodic table contains the noble gases? Why are they chemically inert?

Example 4 medium

An element is in Group 17 and Period 3 of the periodic table. What do the group and period tell you

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