Atoms, Molecules, and Elements

Atoms, Molecules, and Elements
Take a look out the window. Consider that everything that you can and cannot see is composed of atoms. Some of these may be bonded with other atoms to form molecules. All matter is composed of atoms that are too small to see. Weather the matter is liquid, gas or solid, pure or a mixture. It is the basis for elements that make up what we know today as our periodic table.
Demetri Mendeleev was trying to organize the elements into a table by weight when he noticed that as the weights increase occasionally the properties of one element would resemble those of an element he already listed so he placed these elements in a column under the ones they resembled chemically ( Capri, PhD, 2003). Each chemical in the vertical rows on the periodic table are considered families or groups because they have properties that are similar to each other.
All the chemicals in group 1A of the periodic table are considered alkali metals. Alkali metals are similar in that each of them has only one atom in the outermost shell and they are very reactive when combined with other elements. All elements in column 7A are halogens. Halogens are also highly reactive oxidizing agents that are called “salts”. All halogens have 7 electrons in their outer shells, giving them an oxidation number of -1 ( Bodner Research Web, n.d.). Noble gases can be found in Column 8A. These elements are all considered to belong in this column because they are all gases that are considered unreactive due to their shells being closed. The RSC.org ( n.d.) website states “and can all be found in the smallest of quantities the atmosphere itself”. These gases according to the Chemical Elements.com (1996-2009) website, “have the maximum number of electrons possible in their outer shell (2 for Helium, 8 for all others), making them stable.” Due to Mendeleev’s structure in his periodic table, the position of the elements due to their similar characteristics shows their reactive or non-reactive qualities.
The Halogens are all atomic elements because they can all be found in nature. If you were to combine two or more of these nonmetals, you would get a molecular compound such as . The first being Ammonia and the later of course water. A molecule is a chemically bonded unit of atoms with distinct chemical properties. Most molecules are combinations of two or more atoms of different elements. Chlorine exists in nature as a diatomic molecule. This arrangement allows two chlorine atoms to share their outermost orbit electrons, achieving stability, compared to the single atom. The Clark (2000) website states, “While most molecular substances are insoluble, the combination of ammonia and water above produces a situation where some of the ammonia, reacts with the water to produce ammonium ions and hydroxide ions. .” This reaction doesn’t complete itself and only 1% ammonia will react to form the ammonium ions.
Each electron has a certain number of electrons that exist in the energy levels called shells of the elements. These shells can also be broken down into subshells The electronic structure of atoms tells the chemist which energy level or subshell, and orbital are occupied by electrons in any particular atom. Knowing this electronic structure of atoms can aid chemists by helping them determine how the elements will bond together and why they behave in different ways. Each subshell hold a certain amount of electrons and the s subshells hold 2, the p subshells hold 6 and d subshells hold 10 electrons (Tro, N. J. (2009).
The understanding of atoms is one that can be overwhelming when you consider that everything in the physical world can be broken down into atoms. From this understanding it takes us into the world of combing atoms to form compounds. Taking the content of the compounds or the chemical formula and forming molecules, Molecular matter follows the lead of its molecules and iconic matter follows the lead of its ions. The periodic table can seem challenging to learn however, if you understand Mendeleev’s concepts of organization in the rows and columns, it is quite easy to grasp.

References:
Capri, Ph.D, A. (2003). The Periodic Table of Elements. Vision Learning. Retrieved 5/14/2011 from http://www.visionlearning.com/library/module_viewer.php?mid=52
Bodner Research Web. (n.d.). The chemistry of Halogens. Retrieved 5/5/2011 from http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch10/group7.php
RSC.org. (n.d.). Group 18- The Noble Gases. Retrieved from http://www.rsc.org/chemsoc/visualelements/pages/data/intro_groupviii_data.html
Chemical Elements.com. (1996-2009). Periodic Table:Noble Gases. Retrieved from http://www.chemicalelements.com/groups/noblegases.html
Clark, J. (2000). MOLECULAR STRUCTURES. ChemGuide.com. Retrieved from http://www.chemguide.co.uk/atoms/structures/molecular.html
Tro, N. J. (2009). Introductory chemistry. (3rd ed.). Upper Saddle River, NJ: Pearson/Prentice Hall.