Introduction/Background
     Elements in the periodic table are generally sorted into two categories: Metals and Non-Metals. Metals are found in the middle and on the left hand side of the periodic table (Groups 1A and 2A and all the B groups). Non-metals are found on the right hand side of the periodic table (Groups 3A-8A).

This separation is very important because metals and non-metals not only react differently but they also bond differently when they form compounds. If you know whether the elements in a compound are metals or non-metals, you can then define the compound as covalent or ionic in nature. When metals and non-metals form compounds they form ionic compounds. When non-metals and non-metals form compounds they form covalent compounds. Metals that are combined with other metals are called alloys. Metals are normally a shiny grayish - silver color. There are some exceptions to this such as gold. Can you think of another common exception? Click to reveal

Metals are also harder than non-metals and are good conductors of heat and electricity. Metals have a lot of value in industry because they can be hammered into a sheet because they are malleable and can be pulled into a wire because they are ductile. These physical properties of metals are all due to the arrangement of their electrons in rows that allows the metal atoms to “slide” past each other when necessary.

Figure 1: What would happen if you struck an ionic compound with a hammer? It would shatter or crunch as the bonds were broken apart.

Figure 2: What would happen if you struck a metal compound with a hammer? It would bend or reshape as the atoms slid past each other.

Key Concepts      The way the electrons are arranged in metals is also responsible for their reactivity. Metals generally undergo three types of reactions:          1) Metals combined with acids – This produces a salt (a metal plus a non-metal ionic compound) and hydrogen gas.          Ex. 2Na(s) + 2HCl(l) → 2NaCl(s) + H2(g)          2) Metals combined with Oxygen – This produces metal oxides.           Ex. 4Fe(s) + 3O2(g) → 2Fe2O3(s)          3) Metals combined with water – This produces metal hydroxides and hydrogen gas.          Ex. 2K(s) + 2H2O(l) → 2KOH(s) + H2(g)      Of the above reactions, the most commonly observed is the reaction of metals with oxygen while in the presence of water. Since the earth’s atmosphere contains oxygen gas, metals are almost always in constant contact with oxygen and this contact creates a continuous arena for reactions to occur. We observe these reactions in our everyday life without even realizing it. Every time you see a rust spot on a car or a green patina on a copper statue , you are observing the results of this type of reaction. These oxidation reactions are often called corrosion since the reaction of the metal ions to form metal oxides often changes the metal’s physical properties in a deleterious manner. That means that the new compound is not as strong or shiny as the old metal and generally means that whatever structure the metal was used in is now ruined.

Rusted Metal on an Old Car

Copper patina (corrosion) on the foot of a statue