periodic+trends

In most single replacement reactions we will study, one metallic element will replace another. This means that one of the metals is more //reactive// than the other. This is called **chemical activity.**
 * The chemical properties of the elements relate to their positions on the periodic table.
 * In other words, an element's location on the table can be used to predict the chemical activity of that element.

__Chemical activity__ is defined as an element's "willingness" to undergo a chemical reaction.
 * Elements like sodium, that oxidize readily in air and react violently in water, are considered highly **chemically active**.
 * Others like helium or neon are completely **inert** (have little or no chemical activity).

The general __trend in chemical activity for the metals__ is as follows:
 * the copper group (Cu, Ag, Au) contains the least chemically active metals
 * chemical activity increases from the right side of the table (near the metalloid line) to the left side (the alkali metals)
 * chemical activity increases from the top of the periodic table to the bottom of the periodic table