An element is a substance that has an entity by itself, that is only one kind of atom. Other substances may be split chemically to yield its components, but with elements, they cannot be split by ordinary chemical reactions. According to the latest count, there are 92 natural elements with 20 artificially made. Artificial elements are created by bombarding isotopes of some elements with radiation. A student can study elements using the periodic table of elements.
The periodic table of elements is a comprehensive summary of all the elements that have been recognized. It contains information such as atomic number, atomic mass, electronic configuration, melting and boiling points, groups and periods. The idea for the development of the periodic table of elements was started by Dmitri Mendeleev. With the introduction of new concepts, the table was revised until it became what it is today.
Basically, an element can either be a metal or non-metal. Metals are described as elements with valence electrons that range from one to three. Valence electrons refer to the outermost shell of the atom of an element. For an element to achieve stability, the valence electrons must be equal to eight. Non-metals are described as either gases in room temperature or elements having valence electrons of five to seven. This information can only be seen as oxidation states in the periodic table. Oxidation states can be used to determine the proportion of elements during chemical reactions. There are four types of chemical reactions: combination, decomposition, replacement and double replacement. Combination is simply the addition of two elements to form a substance. Decomposition breaks down a compound to its respective components. Replacement displaces a component of a compound by another component which is more active than the component replaced. Double replacement exchanges one component of each two compounds with each other. Chemical reaction requires energy to happen, this energy is called activation energy, either to break or combine. To form compounds, two types of bonds commonly happen: ionic and covalent. Ionic bond usually happens with donation of electron form a metal to a non-metal to form a valence shell of eight electrons. Covalent bonds involve sharing of electrons between non-metals to form the required valence shell.
Posted 2010-12-14 and updated on Dec 14, 2010 7:03am by crisd