Atoms, Molecules, and Elements

Topics: Chemistry, Periodic table, Chemical element Pages: 2 (511 words) Published: July 20, 2014
Atoms, Molecules and Elements
Atoms, molecules and elements are the building blocks of everything we can see, hear, and touch. Though not visible to the naked eye, it is the combination of millions of these tiny substances that make us who and what we are today. Many elements make up the world around us, and each element reacts differently to its surroundings. The definition of reactivity as pertained to chemistry states, “The relative capacity of an atom, molecule, or radical to undergo a chemical reaction with another atom, molecule, or compound” (Reactivity, 2014). The reactivity of some elements or gases is greater than that of others. When Dmitri Mendeleev created the periodic table he arranged the elements based on their relative atomic mass. Alkali metals are very reactive when mixed with other elements and are placed in Group 1A of the periodic table. There are also extremely reactive nonmetal elements called halogens and are known to be in group 7A in the periodic table. Both the alkali metals and the halogens (nonmetals) on considered to be main group elements. When the number of outer shell electrons is closer to one or seven the higher the elements reactivity. Alkali metals contain a single electron in their outer shell which makes them highly reactive and halogens contain only seven electrons in their outer shell. Noble gases, such as helium, are not reactive because they are chemically stable and will not combine with other elements. H₂S and H₂O are molecules formed from atoms that share similar properties. While the molecular structure of these compounds looks similar they are actually very different. When H₂O is combined a liquid is formed whereas H₂S forms a gas. What is meant by the electronic structure of an atom? This describes how the electrons are organized around the nucleus of an atom. The protons and electrons of an atom both have an electrical charge. While a proton has a positive charge, an electron has a negative charge and when...

References: Reactivity. (2014, July 7). Retrieved from
Science Southwestern Advantage. (2011). Nashville: Southwestern/Great American Inc.
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