Periodic Table of Elements
The periodic table is a useful table that helps scientists obtain information before experimenting or testing anything. There are three main groups on the periodic table metal, nonmetal, and metalloids. Each element can be classified into one of these categories.
The scientific definition of an element is “a pure substance that cannot be separated into any simpler substance by physical or chemical means” (Holt, 2002, 753). A pure substance is a substance in which there is only one type of particle. This includes elements as well as compounds (Holt, 2002, 758). The first group on the periodic table is metals. Metals are elements that are shiny, as well as good conductors of thermal energy and electric current.
Most metals are malleable and ductile. Some examples of metals are lead, copper, tin, and iron. Until the end of the 13th century, only seven metals were known: gold, copper, silver, lead, mercury, iron, and tin. These metals are called metals of antiquity (Levi, 1984, 39). The second group on the periodic table is nonmetals. Nonmetals are elements that are dull and poor conductors of thermal energy as well as electric currents.
Some examples of nonmetals are bromine, sulfur, carbon, and neon. The last major group on the periodic table is metalloids. Metalloids are considered the “in between” elements and have properties of both metals and nonmetals. Sometimes this group is referred to as semi conductors. Some examples of common metalloids are boron, silicon, and antimony (Holt, 2002, 756). The three main categories metals, nonmetals, and metalloids can be broken up into other categories such as halogens and noble gases.
Halogens are one of the more specific, smaller categories shown on the periodic table, which places left of the noble gases. Halogens have a high tendency to be very chemically reactive, which is why they are never found, in pure form, in nature. The group of halogens contains astatine (At), iodine (I), bromine (Br), chlorine (Cl), and fluorine (F). Noble gases are any of the seven elements that make up a more specified group of non-metals. These seven non-metals are helium (He), neon (Ne), argon (Ar), krypton (Kr), xeon (Xe), radon (Rn), and element 188, Ununoctium (Uuo).
All of the pure, noble gas elements are clearly found in the air and make up approximately 0.96% of Earth’s atmosphere, but noble gas compounds make up only a fraction of the atmosphere on Earth (Halka, 2010, 84). Some elements have been known for thousands of years but we have no idea who, or even how, they were discovered. “Some of the oldest elements are lead, antimony, iron, arsenic, carbon, copper, gold, tin, mercury, sulfur, and silver” (Chemicool, 2012, WWW). Lead is relatively heavy, soft, and malleable.
Lead is also a very toxic metal. In 3500 B.C.E., the ancient Egyptians had already started working with lead.
Phoenicians and Romans mined lead in Spain where it was used to manufacture lead pipes. Romans also used lead in facial powders, mascaras, coinage, paints, and plumbing systems. Nowadays, most plumbing systems are made of aluminum, copper, and/or plastic to prevent lead poisoning to the body (Halka, 2010, 58). Until the 1970’s, lead was a major component in most paints because it improved the durability, heat resistance, and prevents decomposition in the product. By the 1950’s, it became acknowledged that the effect of lead absorption into the human system caused people to become extremely ill.
As a result, most paint manufacturers adopted a policy limiting the lead content in indoor paints to less than 1%. In 1973, the legal upper limit became 0.5% and later in 1978, only five years later, it was further reduced to only 0.06%. This drastic reduction indicated the severity of lead inside the human body (Halka, 2010, 64).
After the discovery of lead, history tells us that the next major breakthrough was the invention of gunpowder. It remarkably changed the course of warfare and thus world history was completely changed. According to myth or legend, a Chinese cook unintentionally invented gunpowder 2,000 years ago by inadvertently mixing the incorrect amounts of sulfur, charcoal, and 7.5 parts saltpeter or potassium nitrate (KNO3) (Halka, 2010, 117). Around 1000 C.
E., the Chinese utilized the phenomenon to make fireworks. The first fireworks were invented using bamboo stuffed with saltpeter and a wick. It had been known that they tied these to arrows and delivered to the enemies in battle as a substitute of an early form of a “gun” (Halka, 2010, 116). Gunpowder and fireworks are both considered explosives, but it was not until after the Crusades were underway in the 13th century that the Europeans were finally introduced to small explosives.
Arabian scientists formed “fire arrow” projectiles against the infidels. Word about this was soon brought to Europe, most likely, by the famous Italian writer/traveler Marco Polo. Italians were the first Europeans to find an artistic use for gunpowder that produced beautiful fireworks for entertainment at festivals, parties, and special events (Halka, 2010, 117). There were many significant people when talking generally about elements. Certain people are credited for identifying certain elements, such as Marie Curie and Ferdinand-Frederic-Henri Moissan, while others, such as Dmitri Mendeleev and Glenn Seaborg, were known for the layout of the periodic table.
Marie Curie was credited with discovering radium. Marie had lots of family issues including many deaths in her immediate family causing her financial support to never be constant and stable. At the time, a woman receiving an education was completely unheard of, but despite the odds always being against her, she taught herself to read and write through books and later the Floating University, as a substitute for college. This illegal university met at night in attics fleeing at any noise that could’ve been the Russian Police (Poynter, 1994, 14). Ferdinand-Frederic-Henri Moissan was yet another early scientist who had a huge impact on world history. There have been many attempts to isolate certain components of hydrofluoric acid, nicknamed “Fatal Fluorine”.
In 1850, Paulin Louyet, a Belgian chemist, attempted to isolate fluorine gas and died trying at the age of 32 (Halka, 2010, 14). “Even if chemists succeeded in safety preparing a small quantity of fluorine gas, the gas would immediately react with its surroundings, so obtaining pure samples remained elusive until 1886” (Halka, 2010, 15). This statement was very popular until the early 1900’s when Ferdinand-Frederic-Henri Moissan of France, finally proved them wrong. He had finally isolated the fluorine gas after poisoning himself several times in his first attempts. He accomplished this by dissolving potassium fluoride in liquid hydrofluoric acid, excluding H20 (water) completely, safely preparing the fluorine gas.
Right before Ferdinand-Frederic-Henri Moissan died in 1907, he received the 1906 Nobel Prize for Chemistry for his development of the electric furnace as well as his isolation of fluorine. Another chemist that truly revolutionized the elements’ industry was Dmitri Mendeleev. He is well known for developing the format of the periodic table. In 1869, he invented the periodic table of elements; at this time, atomic numbers had not yet been discovered. As a result, there were no “gaps” in the periodic table. The sequence Mendeleev created started reasonably with sodium, fluorine, potassium, chlorine, rubidium, bromine, and so on (Halka, 2010, 59).
In total, there are millions of people noteworthy in the field of elements, but three people truly developed the industry. The last major change in the periodic table came in the middle of the 20th century. American physicist Glenn Seaborg (1912-1999) and his colleagues discovered two new elements with atomic numbers greater than that of uranium (92). Seaborg rearranged the table to accommodate the new elements. Seaborg’s colleagues are carrying on his legacy by currently looking to discover new elements in their labs (Levi, 1984, 23). When elements are combined they can produce materials that take on different qualities than their constituent materials.
Alloys are made of metals combined with one or more other metals/nonmetals. Alloys can be brass, steel, and iron/carbon aircrafts. Steel consists of small amounts of carbon added to iron. Brass is an alloy of copper and zinc that is more malleable than either of the two elements separated. It also has good acoustic properties that make it ideal for musical instruments such as trumpets and tubas. On its own, iron is strong, but brittle.
Adding carbon makes it more flexible. Some materials need to have properties that certain metals, alone, do not provide. For example, aircrafts need to be made of alloys that can withstand high temperatures and high stresses. Such alloys may contain more than ten different elements to achieve the desired results (Levi, 1984, 42). Lead and bismuth are the heaviest elements on the periodic table with stable isotopes.
Lead is a soft, bluish-white solid with about the high density of 11.34g/cm3. Bismuth is a reddish-white solid with about a density of 9.78g/cm3 (Halka, 2010, 53). Fluorine is the 13th most abundant element found in the Earth’s crust with minerals containing the fluorine ion (F-).
Fluorine gases are extremely difficult and hazardous to work with, so only specially trained people under careful, controlled conditions can handle it in gas form (Halka, 2010, 9). Argon is formed by the radioactive decay of unstable potassium isotopes. Being that potassium is an abundant element on Earth, sizeable amounts of argon can be produced. In fact, argon comprises about 1% of Earth’s atmosphere, making it the most abundant noble gas in the atmosphere and the third most abundant gas in the atmosphere (Halka, 2010, 85). Chlorine is element number seventeen. It is the 20th most abundant element found in Earth’s crust and common in most seawater.
In nature, it is most commonly found in the form of chloride ion (Cl-). Sodium chloride, also known as common table salt (NaCl), has been used since prehistoric times to preserve meats and flavor foods. In its purest form, chlorine is an odorous, pale-green gas in the form of gaseous diatomic molecules with the formula of (Cl2). Because chlorine gases, and other forms of chlorine, are such powerful oxidizing agents, chlorine is used in many countries around the world to disinfect municipal drinking water supplies and to treat water in swimming pools (Halka, 2010, 21). Each element gets its name from somewhere and each element has its own statistics and facts that characterize it.
These are some of the more common elements named after places. Americium (the Americas), Californium (California), Europium (Europe), Francium (France), Holmium (Holmia – Latin for Stockholm), Lutetium (Lutetia – Latin for Paris), Magnesium (Magnesia, Greece), and Polonium (Poland) are all elements named after places on Earth. Elements can also be named after people. Sometimes the element is named after the person itself, used as a tribute to a famous deceased or a religious god. Bohrium (Niels Bohr), Curium (Pierre and Marie Curie), Einsteinium (Albert Einstein), Helium (Helios, Greek god of the sun), Mendelevium (Dmitri Mendeleev), Nobelium (Alfred Nobel), Selenium (Selene, Greek goddess of the moon), Tellurium (Tellus, Latin for Earth), and Thorium (Thor, Scandinavian god of thunder) (Levi, 1984, 31).
The periodic table contains many elements with differing properties. The name gold derives from the Sanskrit jval “to shine”, the Teutonic world “gulth” for shining metals, and the Anglo-Saxon gold of unknown origin. The chemical symbol, Au, derives from the Latin aurum for Aurora, the Goddess of Dawn. It was known and highly valued since prehistoric times (Holden, 2004, WWW). The name hydrogen derives from the Greek root “hydro-” meaning water and “genes” for forming, since it burned in the air to form water. An English physicist, Henry Cavendish, discovered hydrogen back in 1766.
This element has been known since prehistoric times. The chemical symbol, Pb, is derived from the Latin word for lead, “plumbum” (Holden, 2004, WWW). In the element selenium, different ionic states produce different color hues. The isotope of Se2- creates a reddish brown hue, but only Se0 makes the gorgeous pink desired in the production of clear glass. The making of clear glass is a complex procedure, because the average human eye can see up to 40,000 different hues.
This causes glass-making companies to often combine cobalt to counteract the pink hues of selenium. This method is based on the principle of complementary colors. The ratio dosage is difficult to control because selenium prefers to vaporize, losing about 90% of selenium added, rather than mixing with the glass melts. Each element on the periodic table has its own boiling and melting points. In Celsius, Carbon melts at 3527 and boils 4027. Nitrogen melts at -210 and boils at -196.
Oxygen melts at -218 and boils at -183. Fluorine melts at -219 and boils at -188. Finally, neon melts at -248 and boils at -246. Cobalt melts at 1495 degrees Celsius with a density of 8.9g/cm3 (Levi, 1984, 31).
Cobalt conducts thermal energy and is unreactive with oxygen in the air. Iron melts at 1535 degrees Celsius with a density of 7.9g/cm3. Iron conducts electric currents as well as thermal energy and combines slowly with oxygen in the air to form rust (Lady Liberty). Nickel melts at 1455 degrees Celsius with a density of 8.
9g/cm3, similar to cobalt. Nickel conducts electric currents as well as thermal energy just like iron but, just like cobalt, is unreactive with oxygen in the air (Holt, 2002, 83). Carbon’s chemical symbol is “C”. It is a nonmetal, combustible, and a solid. It comes in four allotropes: diamond, white carbon, graphite, and buckminsterfullerene. Carbon is found everywhere and is not credited to one single person for discovery.
It has six protons, six neutrons, and six electrons. The density of carbons allotrope diamond is 3.5g/cm3 and 2.2g/cm3 for the allotrope of graphite. Mars, Venus, and Jupiter’s moon Io, have been a recent topic of interest to many scientists.
Certain elements have been found on all three planets/moon that give us hope that there are other life forms outside of Earth’s atmosphere. The Martian atmosphere is a mix of xeon isotopes differing of that from Earth. Xeon is also used for exotic propulsion and thrust. Exotic propulsion is what the Voyager I ran off, travelling at 38,000 miles per hour (Halka, 2010, 98). On the surface of Venus, there have been recent discoveries of lead and bismuth “snow”. This greenhouse planet is too warm for the type of snow seen on Earth, but at higher altitudes, conditions seem to be cool enough for both elements’ sulfides to condense from the atmosphere and fall to the ground (Halka, 2010, 56).
This sensation of “snow” on Venus was first observed in 1995 as bright, reflective areas in mountainous regions of the planet. A lander mission to Venus would be required in the future, collecting soil samples and retaining photographic evidence would be necessary to confirm this testimony (Halka, 2010, 57). Chlorine’s atoms have been detected on Jupiter’s innermost moon Io. This small moon is not massive enough for gravity to hold onto its entire atmosphere, so much of it escapes into space. Future hovercrafts may be sent by NASA to investigate the gravity of Jupiter and its effect on Io, causing the atmosphere to remain somewhat stable (Halka, 2010, 24). The current research of elements is always evolving, whether it’s scientists attempting to create new chemical bonds, to struggling to produce a more modern format of the periodic table, or to even trying to generate new lab-developed elements with higher atomic numbers.
While the discovery of the element 117 has not been yet reported, it’s reasonable to assume that it will be discovered fairly soon. Since it will lie between astatine in the periodic table, it should therefore be a halogen and a solid, like iodine and astatine. If scientists/chemists succeed in synthesizing weighable quantities of element 117, it should prove to be the most metallic halogen, since the trend in the periodic table is for the metallic nature of elements to increase upon descending a column (Halka, 2010, 110). In January of 2004, a team of American and Russian scientists announced the creation of two new super dense elements. The high density of each element is cause by its large atomic mass and high atomic number. Both fill the gaps in the lower end of the periodic table.
The first element was Ununtrium (Uut) and the second was Ununpentium (Uup). The two elements have not officially been approved because other laboratories must confirm the existence of them (Saucerman, 2005, 15). We don’t know what the future will hold in the field of elements. New elements are being approved and discovered every day. Elements such as Ununtrium and Ununpentium will most likely be ratified as official elements sometime in the near future as soon as another chemist lab authorizes their actuality. Now that new elements have been found on Io, Mars, and Venus, missions may be sent in the future to further investigate.
From the uses of lead in paints, to selenium isotopes and cobalt in glass, the periodic table is a vital part of science. Scientists such as Marie Curie, Ferdinand-Frederic-Henri Moissan, Dmitri Mendeleev, and Glenn Seaborg have paved the path for chemists and changed world history forever. Chemists are creating and discovering new chemical bonds, isotopes, and uses for elements every single day.