June 14th, 2015
The Composition of Chemistry
Chemistry is made up of so many different things, but at the core of it all is the understanding of the periodic nature and properties of atoms and molecules. The concepts of chemistry are based around these ideas as everything in chemistry is created from atoms. The understanding of the makeup of atoms has come a long way since the beginning. Now we know that atoms are made up of a nucleus, which houses the protons & neutrons, and outer shells, which hold electrons. The charges from the protons and electrons even each other out to make the charge of an atom neutral. Sometimes though, in certain reactions, atoms give up or take in certain charged particles to make themselves positive of negative ions. Neutrons have no electrical charge while protons have a positive charge and electrons have a negative charge. Elements on the periodic table are identified by how many protons they have in their nucleus. This is how each element gets their atomic number. Atoms are organized on the periodic table by the atomic mass and atomic number, as well as in like groups of elements which behave in similar ways. A molecule is the smallest particle of a substance which still exhibits the properties of that substance. Molecules are two or more atoms held together by chemical bonds and have no electric charge.
Mendeleev is the father of the periodic table, and he organized it in a very precise and methodical way. He researched different types of elements and organized them together in groups on the table in relation to their types as well as the way in which they react with others (families or groups). Halogens and alkali metals are extremely reactive, whereas noble gases do not react at all. Noble gases are chemically inert; they are stable and will not combine with other elements to form compounds. They do not combine with other elements because they have the maximum number of valence electrons; therefore they have a full outer shell and do not take part in chemical reactions. These are the safest elements. Alkali metals, on the other hand, are very reactive and can cause dangerous explosions when combined with other elements. Halogens are very reactive nonmetals. Alkali metals are in the first period on the periodic table, they have 1 valence electron. Halogens are in the 7th period of the main elements and have 7 valence electrons. Both are highly reactive and want to complete their outer shell so they often combine to do so.
When molecules form from atoms of similar families (for example H20 and H2S) they share some characteristics, but do not necessarily act the same. While H2O and H2S have almost identical molecular structures and are both bent, H2O is the only one affected by hydrogen bonds. H2S has a much lower boiling point (as it is affected by the London dispersion forces) and is not