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The Periodic Table

The vertical columns of elements represented in the periodic table are called groups, and the horizontal rows are called periods. There are seven periods in the periodic table. The groups are usually designated by roman numerals followed by the letter A or B as shown in the periodic table.
The groups IA through VIIA are called the representative elements. These elements have either s or p orbital valence electrons. The last group in the periodic table is the noble gas group otherwise known as the zero group. The groups ranging from IB through VIII are called transition metals, and finally the metals from lanthanum through hafnium and metals from actinium onward are called the inner transition metals.

We will discuss some of these groups.

Group IA

The Group IA contains hydrogen, lithium, sodium, potassium, rubidium, cesium, and francium. The Group IA elements are also known as alkali metals, with the exception of hydrogen which is not a metal. Alkali metals are very reactive.

All of them react with water to form alkaline solutions.

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The reactivity of alkali metals to water increases from top to bottom of the periodic table.
For example, potassium reacts much more rapidly than lithium. They can also form oxides
(For example, lithium can form oxides such as Li2O.) and a variety of other compounds, since they are highly reactive. Alkali metals are good electrical and thermal conductors. All of them have one valence electron in their outer most shell, which is in the s orbital in the ground state. The Group IA elements usually exhibit an oxidation state of +1. They have a valence shell configuration of ns1.

Group IIA

The Group IIA elements are called alkaline earth metals. The alkaline earth metals consist of beryllium, magnesium, calcium, strontium, barium, and radium. Their oxides are basic. They have a valence shell configuration of ns2, and exhibit an oxidation state of +2. These elements are not as reactive as alkali metals.

Metallic character decreases from left to right along a period, and increases from top to bottom of a group.

Group IIIA

The Group IIIA elements consist of boron, aluminum, gallium, indium, and thallium. They have a valence shell configuration of ns2np1. They usually have oxidation states of +1 and +3.

Group IVA

The Group IVA is the carbon family. Carbon is the most versatile element, and thus it has its own separate subject. Yes, you guessed right – organic chemistry. Carbon can exist in many different forms by itself such as graphite and diamond. These forms of carbon are very contrasting in the sense that graphite is relatively soft whereas diamond is very hard. The Group IVA elements have a valence shell configuration of ns2np2.
The carbon family consists of carbon, silicon, germanium, tin, and lead. All these form oxides which look like CO2 (e.g., SiO2, PbO2). They also form monoxides. As medical enthusiasts, you probably have heard of carbon monoxide, and its harmful effects. CO is a colorless and odorless gas, and it has even higher affinity for hemoglobin than oxygen in the red blood cells.

Group VA

The Group VA is the nitrogen family. The group consists of nitrogen, phosphorus, arsenic, antimony, and bismuth. Nitrogen is a diatomic, colorless, and odorless gas, and is not a very reactive element. The Group VA elements have a valence shell configuration of ns2np3.

Group VIA

The Group VIA elements are oxygen, sulfur, selenium, tellurium, and polonium. They have a valence shell configuration of ns2np4. Oxygen (O2) is a diatomic gas, and it also exists in an allotropic form called ozone (O3). Sulfur forms acidic oxides (e.g., SO2, SO3).

Group VIIA

The Group VIIA is more commonly known as the halogen family of elements. They are fluorine, chlorine, bromine, iodine, and astatine. They have an outer configuration of ns2np5. Halogens are highly reactive nonmetals, and form diatomic molecules. Halogens form hydrogen halides which are very acidic. These hydrogen halides can dissolve in water to form aqueous acids (e.g., HCl).
Fluorine - yellow gas
Chlorine - greenish-yellow gas
Bromine - reddish brown liquid
Iodine - dark colored solid


The elements of the Group VIIIA, otherwise known as noble gases are extremely unreactive. They are found as non-combined forms in nature. Because of this, they are called inert gases. They have an outer configuration of ns2np6.

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