To access the remainder of this piece of premium content, you must be registered with Firehouse. Already have an account? Login
Register in seconds by connecting with your preferred Social Network.
Complete the registration form.
The numbers at the top of the vertical columns on the Periodic Table indicate the number of electrons in the outer shell of the elements in that column. The exception to this is the transition elements between the two towers on either end of the table. Unlike the primary elements, the numbers above the transition metal columns do not indicate the number of electrons in the outer shell of these elements. The transition elements can have differing numbers of electrons in their outer shells.
Vertical columns on the Periodic Table contain elements that have similar chemical characteristics in their pure elemental form. These elements have the same number of electrons in the outer shell. This is why they have similar chemical behaviors. These similar elements are sometimes referred to as families. Some of the more important families include: the alkali metals in column one, the alkaline earth metals in column two, the halogens in column seven, and the noble or inert gases in column eight.
The alkali metals in column one begin with lithium and continue through sodium, potassium, rubidium, cesium and francium, which are liquids at normal temperatures. The alkali metals are water reactive. They react violently with water, producing flammable hydrogen gas and enough heat to ignite the gas. These elements are so reactive that they do not exist in nature as the pure element. They are found as compounds of the metal such as potassium oxide and sodium chloride. Some isotopes of cesium and all isotopes of francium are radioactive. These elements are somewhat rare, so you are not likely to see them on the street.
The alkaline earth metals in column two are less reactive than the alkali metals in column one. Beryllium does not react with water at all. The others have varying reactions with water. Alkaline earth metals are all solids. They have to be burning or in a smaller physical form before they become water reactive. Magnesium, for example, is extremely water reactive when it is involved in fire. The application of water to a magnesium fire will cause violent explosions which can endanger responders. If it is necessary to fight fires involving magnesium, water should be applied from a safe distance with the use of unmanned appliances. Other elements in column two are also water reactive to varying degrees. These include calcium, strontium, barium and radium, which is radioactive.
The halogens in column seven are non-metals. They may be solids, liquids or gases. Fluorine and chlorine are gases at normal temperatures and pressures. Bromine is a liquid to 58 degrees Celsius and produces vapor rapidly when above that temperature. Iodine is a solid; astatine is a radioactive solid but you are not likely to encounter it. Halogens are all toxic and are strong oxidizers; fluorine is a much stronger oxidizer than oxygen. In fact, fluorine is the strongest oxidizer known.
In the pure elemental form, halogens do not burn but they will accelerate combustion much like oxygen because they are oxidizers. Some halogen compounds are components of fire extinguishing agents called halons. Halons are being phased out because of the damage they cause to the ozone layer of the earth's atmosphere.
Elements in column eight are all gases. They are non-flammable, non-toxic and non-reactive. Family eight elements are sometimes referred to as the inert or noble gases. Normally they do not react chemically with themselves or any other chemicals. Helium is used for weather balloons and airships. Neon is used for lighting and beacons. Argon is used in electric light bulbs. Krypton and xenon are used in special light bulb for miners and in light houses. Radon is radioactive and is used in tracing gas leaks and treating some forms of cancer.
The noble gases have a complete outer shell of electrons, two in helium and eight in the rest. It is because of the complete outer shell of electrons that the noble gases do not react chemically. All of the other elements on the periodic table try to reach the same stable electron configuration. The reason why chemical reactions occur is because the elements are trying to reach stability.
Column eight elements are all non-flammable and non-toxic gases. However, they can displace the oxygen in the air and cause asphyxiation inside of buildings or in confined spaces. Most of the noble gases are present in the air like nitrogen and oxygen. Inert gases are commonly shipped and stored as compressed gases or cryogenic liquids.