While every element on the periodic table has a unique atomic structure, similarities in these structures yield elements with similar attributes. Most of these attributes are linked to the atomic orbital formation within them. In this introduction, I’m going to be working left to right, across the periodic table. Also note that when I refer to group, I am referring to that column of the periodic table.
Group One ~ The Alkali Metals
This category includes the first group of the periodic table except for helium, which is a non-metal. The alkali metals are noted for being highly reactive, and they rarely occur naturally. Because they have only one valence electron, these elements are unstable and quickly combine with other elements to complete their electron shell. Reactions involving these elements are often extremely exothermic, so great care must be taken in their storage and use. Most of these metals must be stored in oil, because they react violently with water and oxidize when left in the air. These elements are most often found bonded to elements from group 17, the halogens, forming common compounds known as salts. The most common would be NaCl, also known as table salt.
Group Two ~ The Alkaline Earth Metals
This category includes the second group of the periodic table. Like the alkali metals, the alkaline earths are highly reactive and do not generally exist naturally. However, many may be familiar with their oxides, such as lime (a common ingredient in mortar and plaster) and magnesia (used to preserve books and cure heartburn). Like alkali metals, these are often stored in oil to prevent oxidation.
Groups Three-Twelve ~ The Transition Metals
Through this section of the periodic table, the elements are filling up the ‘d’ orbitals of their atomic structure. Metals are generally stable in the environment, and while they do tend to lose their valence electrons easily, the reactions often require energy. Because of this, many metals make good catalysts for other reactions. All of the metals, aside from mercury, are solid at room temperature, and most have high melting and boiling points. However, metals are often malleable solids, allowing them to change shape at lower temperatures. Metals with higher malleability such as gold, silver and mercury tend towards the right while harder metals are on the left. Because the valence electrons move freely, metals are usually good conductors of heat and electricity.
Groups Thirteen-Sixteen ~ Poor Metals, Metalloids and Non-Metals
This section of the periodic table doesn’t split cleanly by group. As the p’ orbitals fill up, elements change so quickly from one to another that they are better characterized in diagonal strips than by vertical groups. Of these four groups, the bottom left encompasses the poor metals, the upper right holds the non-metals, with the metalloids (boron, silicon, arsenic, germanium, antimony, tellurium and polonium) forming a stair step between them. In general, this is where elements shift from solids (metals) to gases in their natural states, with the metalloids being somewhere in the middle. The poor metals are called such because they characteristically have lower melting and boiling points than the transition metals and are generally softer. Otherwise, they share many of the characteristics of the transitional metals.
The metalloids are ambiguous. While some of them exhibit metallic characteristics, such as antimony, others are decidedly non-metallic like boron. However, they do share several characteristics. Many of the metalloids are useful as semi-conductors, a crucial component of computer chips.
The non-metals are generally gases or brittle solids in their natural states. The most noteworthy is carbon, which is the building block of all life on earth. Others, such as nitrogen and oxygen, comprise the majority of our atmosphere. As a group, the non-metals are poor conductors of heat and electricity, and have much lower melting and boiling points than metals.
Group Seventeen ~ The Halogens
Like group one, they are all highly reactive, because they require only one electron to complete their valence shells. Because they are so reactive, several of them are highly toxic, particularly fluorine and chlorine. As such, these gases don’t usually exist normally in the atmosphere in large quantities. Other than these chemical properties, halogens differ greatly from one another. While fluorine and chlorine are gases at room temperature, iodine is a blue-black solid and bromine is a liquid.
Group Eighteen ~ The Noble Gases
The final group on the periodic table consists of those elements that have completed their octet of electrons in their valence shell. As such, these gases rarely react with elements other than themselves, and are therefore very hard to detect naturally. While they all exist naturally in the atmosphere, the only one with a noteworthy presence is argon, which makes up a little under one percent of the air we breathe.
The Bottom Rows ~ The Rare Earth Metals
This leaves those two rows of elements below the main body of the periodic table, known as the rare earth metals. While they are actually part of the transition metals, what separates the rare earths is they are actually these elements fill in the f’ orbitals in their electron structure. Many of the rare earths readily form oxides when left in the air, so like the alkali and alkali earth metals, they must be carefully stored. In fact, these elements were known only in theory until 1945, when the process of ion exchange and solvent extraction allowed these elements to be harvested in their pure forms. Most of the rare earth metals have a silvery gray luster, and often look so similar they are difficult to distinguish. Many of them are also radioactive. Otherwise, they share many characteristics with the transition metals next to them.
