What is representative element

How many types of elements are there? There are more than different types of atom - one for each element. Differences between the atoms give the elements their different chemical properties. In , there were known elements.

However, those above are highly unstable and have been made in only tiny quantities. Are halogens reactive? The halogens are all elements that are found in group 17 of the periodic table. The halogens include fluorine, chlorine, bromine, iodine, and astatine. All of these elements are considered to be reactive nonmetals.

Because these atoms are so close to having a full set of eight valence electrons, they're very reactive. Is calcium a representative element? Who discovered halogens? Scheele called the element "dephlogisticated muriatic acid", which is how chlorine was known for 33 years. In , Humphry Davy investigated chlorine and discovered that it is an actual element.

What are the main elements? Where are the transition elements? The transition metals are a group of metals that are found in the middle of the periodic table. They all have similar properties. The second set are Group B elements and are also known as transition metals. Representative elements are the most abundant elements on earth.

The Roman numerals above each group dictate the usual number of valence electrons. Groups are further divided into Representative Elements and Transition Metals. Groups 1A and 2A on the left and 3A through 8A on the right are classified as Representative Elements, while those elements in between are classified as Transition Metals. The layout of the periodic table demonstrates recurring chemical properties. Elements are listed in order of increasing atomic number the number of protons in the atomic nucleus and arranged so that elements with similar properties fall into the same columns.

Elements are listed with, among other information, their element symbol, atomic number and atomic mass. The P Block elements or the elements in columns 3A through 8A on the right of the periodic table include:. One of the main uses of the periodic table is to predict the chemical properties of an element based on its location. The name alkaline metal comes from the fact that the oxides of the heavier members of the group react with water to form alkaline solutions.

The nuclear charge increases when going from group 1 to group 2. Because of this charge increase, the atoms of the alkaline earth metals are smaller and have higher first ionization energies than the alkali metals within the same period.

The higher ionization energy makes the alkaline earth metals less reactive than the alkali metals; however, they are still very reactive elements. Their reactivity increases, as expected, with increasing size and decreasing ionization energy. Due to their high reactivity, it is common to produce the alkaline earth metals, like the alkali metals, by electrolysis. Even though the ionization energies are low, the two metals with the highest ionization energies beryllium and magnesium do form compounds that exhibit some covalent characters.

Like the alkali metals, the heavier alkaline earth metals impart color to a flame. As in the case of the alkali metals, this is part of the emission spectrum of these elements. Calcium and strontium produce shades of red, whereas barium produces a green color.

Magnesium is a silver-white metal that is malleable and ductile at high temperatures. Passivation decreases the reactivity of magnesium metal. Upon exposure to air, a tightly adhering layer of magnesium oxycarbonate forms on the surface of the metal and inhibits further reaction. The carbonate comes from the reaction of carbon dioxide in the atmosphere. Magnesium is the lightest of the widely used structural metals, which is why most magnesium production is for lightweight alloys.

At room temperature, barium shows the most vigorous reaction. The products of the reaction with water are hydrogen and the metal hydroxide. The formation of hydrogen gas indicates that the heavier alkaline earth metals are better reducing agents more easily oxidized than is hydrogen.

As expected, these metals react with both acids and nonmetals to form ionic compounds. Unlike most salts of the alkali metals, many of the common salts of the alkaline earth metals are insoluble in water because of the high lattice energies of these compounds, containing a divalent metal ion.

The potent reducing power of hot magnesium is useful in preparing some metals from their oxides. For this reason, a CO 2 fire extinguisher will not extinguish a magnesium fire. Additionally, the brilliant white light emitted by burning magnesium makes it useful in flares and fireworks.

The elements in group 12 are transition elements; however, the last electron added is not a d electron, but an s electron. Since the last electron added is an s electron, these elements qualify as representative metals, or post-transition metals.

The group 12 elements behave more like the alkaline earth metals than transition metals. Group 12 contains the four elements zinc, cadmium, mercury, and copernicium. Each of these elements has two electrons in its outer shell ns 2. In their elemental forms and in compounds, cadmium and mercury are both toxic.

Zinc is the most reactive in group 12, and mercury is the least reactive. This is the reverse of the reactivity trend of the metals of groups 1 and 2, in which reactivity increases down a group. The increase in reactivity with increasing atomic number only occurs for the metals in groups 1 and 2. The decreasing reactivity is due to the formation of ions with a pseudo-noble gas configuration and to other factors that are beyond the scope of this discussion.

The chemical behaviors of zinc and cadmium are quite similar to each other but differ from that of mercury. Zinc and cadmium have lower reduction potentials than hydrogen, and, like the alkali metals and alkaline earth metals, they will produce hydrogen gas when they react with acids.

Zinc is a silvery metal that quickly tarnishes to a blue-gray appearance. This change in color is due to an adherent coating of a basic carbonate, Zn 2 OH 2 CO 3 , which passivates the metal to inhibit further corrosion.

Dry cell and alkaline batteries contain a zinc anode. About half of zinc production serves to protect iron and other metals from corrosion. This protection may take the form of a sacrificial anode also known as a galvanic anode, which is a means of providing cathodic protection for various metals or as a thin coating on the protected metal.

Galvanized steel is steel with a protective coating of zinc. A sacrificial anode , or galvanic anode, is a means of providing cathodic protection of various metals. Cathodic protection refers to the prevention of corrosion by converting the corroding metal into a cathode. As a cathode, the metal resists corrosion, which is an oxidation process. Corrosion occurs at the sacrificial anode instead of at the cathode.

The construction of such a system begins with the attachment of a more active metal more negative reduction potential to the metal needing protection. Attachment may be direct or via a wire. To complete the circuit, a salt bridge is necessary. This salt bridge is often seawater or ground water. Once the circuit is complete, oxidation corrosion occurs at the anode and not the cathode. The commonly used sacrificial anodes are magnesium, aluminum, and zinc. Magnesium has the most negative reduction potential of the three and serves best when the salt bridge is less efficient due to a low electrolyte concentration such as in freshwater.

Zinc and aluminum work better in saltwater than does magnesium. Aluminum is lighter than zinc and has a higher capacity; however, an oxide coating may passivate the aluminum. In special cases, other materials are useful.

For example, iron will protect copper. Mercury is very different from zinc and cadmium. Many metals dissolve in mercury, forming solutions called amalgams see the feature on Amalgams , which are alloys of mercury with one or more other metals.