Alphabet for the Universe

What is an element?

An element is a substance made from only one type of atom. Oxygen gas is made up of only oxygen atoms, and Magnesium metal is made from only magnesium atoms. Basically, these elements cannot be broken down into any simpler form.

If you look around, you will find examples of elements everywhere. The lead in your pencil is made of only carbon. Diamonds are also made from carbon, as is the black charred substance on burnt toast! Carbon is a complex and immensely important element.

You may own silver, gold or platinum as jewelry. Aluminum foil may be tucked in your kitchen drawer, copper is likely to be present in your electrical wires or water pipes, and iron might be causing your car to rust. Elements can be seen everywhere in our daily lives.

Compounding into new forms

Individual elements can be combined in millions of different forms. Elements bond with different elements to make compounds. When this happens, the properties of the compound are usually vastly different than each individual element. A classic example is sodium, which is a highly reactive metal that can be set on fire in water. It reacts with a green, poisonous gas called chlorine, to produce sodium chloride.

Sodium chloride is also the chemical name for table salt; a relatively harmless substance that makes your chips taste great. Table salt is clearly different than the two elements used to make it, and it is this varying combination of different elements that makes the universe incredibly diverse.

The Periodic Table

All elements are arranged on the Periodic Table in a specific order. You can tell a great deal about an element simply by its position on the table. Elements are arranged in order of increasing atomic number from the lightest to the heaviest natural element, Hydrogen and Uranium, respectively. I specify "natural" element, since there are now over 115 elements. Scientists have artificially made every element after Uranium in laboratories.

Elements are also arranged in groups, with the first column being group one, the alkali metals. Group two, the alkali Earth metals, is place in the second column. The middle section is known as the transition metals. Group three is the column starting with Boron and containing Aluminum. The next column is group four, five, six, and seven - known as the Halogens. Group eight finishes with Helium's column, known as the noble gases.

These groups tell us how many electrons (sub-atomic particles) are contained in the outer shells of the elements. Electrons orbit the nucleus of an atom, which is made up of the sub-atomic particles called protons and neutrons. They orbit in clouds or shells. How many electrons are in the outer shell determines the element's behavior, how it reacts and bonds with other elements.

Lithium, Sodium and Potassium are all in group one. They all have one electron in their outer shell. This means that they are extremely reactive as their outer shell is not full, so they try to bond to non-metal elements (at the top right hand side of the table). They need to get rid of their one electron.

Chlorine, on the other hand, belongs to group seven and is desperate to gain an electron, which will complete its shell and make it stable. It reacts and bonds with sodium, resulting in sodium chloride, where sodium "gives" its electron to chlorine.

Group eight elements already have full outer shells, which means they are already in a stable state; therefore, they don't have to lose or gain electrons, resulting in them being inert. They are stable and non-reactive.

The rows of the periodic table are known as periods and dictate how many shells the elements have. If you look at Magnesium, you can tell it has two electrons in its outer shell as it belongs to group two, and it has three electron shells as it is in period three. The elements in their respective groups also react in similar ways. You can see trends in their behavior, which is another reason for their grouping.

Dmitry Mendeleev

The periodic table is a work of genius by Dmitry Mendeleev. He was a Russian scientist whose work on the periodic table defined its modern form. His work on the periodic table and the properties of elements has shaped our understanding of the universe.

When he was alive (1834-1907) there were only 63 known elements. He managed to arrange these elements into groups, depending on their atomic weight and similar properties. He then left gaps in the table where unknown and undiscovered elements were to be placed; accurately describing their appearance, reactivity and properties based on the properties of elements around them. When these elements were discovered, his predictions and descriptions were staggeringly accurate.

What's in a name?

All of the elements on the periodic table have chemical symbols that are recognized internationally. Many of these symbols come from Latin or Greek names. Fe comes from the Latin Ferrum, which we know as Iron. Au, also Latin, means Aurum, which is known as Gold. My favorite is Pb, which stands for Plumbum, also known as Lead. This is how the word "plumbers" originates, from the water pipes that were made from lead in earlier times.

Hydrogen is by far the most common element in the universe. It makes up the majority of a star's mass. Oxygen, Iron, Aluminum, Silicon, Sodium, Potassium, Carbon and Magnesium are the most common elements within the Earth's crust. Our bodies contain all of these elements in various forms.

The most important element for life forms is unquestionably Carbon. Carbon is essential to all known life, and we could not exist without it. Your body is mainly a combination of Carbon, Oxygen, Hydrogen, Iron, Calcium, Phosphorus and Nitrogen. But there's even a trace of Arsenic in you, among other elements. It is the combination of only 92 elements that creates an incredibly diverse universe.

David Canavan has an MSc in Behavioral Ecology and teaches science, math and ICT at Garden International School. David is fascinated by science and loves animals, especially the dangerous kind; the more dangerous the better. You may contact David at davidc@gardenbangkok.com .