Elements, Compounds, and Mixtures

Elements:

Elements are the ingredients all things. An element is a pure substance that cannot be broken down chemically or physically.  An element is a substance that it is not made up other things.  This means that every atom in the element hydrogen (H) is a hydrogen (H) atom. This is not true of pure substances like water.  Water is made of two different elements (hydrogen and oxygen).

There are 118  known elements.  92 elements can be found naturally in earth's crust.  The elements are arranged on the Periodic Table of Element (created in 1869 by Dmitri Mendeleev).  The table is arranged according to its atomic number (the number of protons in the nucleus in each atom of that specific element).

 How to Read the Table.  Look at the atomic number (the upper left in each box) of the desired element(s). Example..lets say nitrogen (N) & gold (Au). All the atoms in the element nitrogen (N) have 7 protons in their nuclei, while all atoms in the element gold (Au) have 79 protons in their nuclei.

                             Periodic Table of Element

             Compounds:

Put different elements together (ex.. hydrogen & oxygen) in certain proporations (chemically bonded of course) and you get a compound.  A compound is a sustance that can be broken down into other sustances (chemically of course) that make up the compound.  You won't find compounds on the Periods Table of Elements because the Table only lists elements. For example: You won't find water on the Periodic Table because water is not an element.  It's made of two different elements (hydrogen & oxygen  H2O).

Here is a list of common compounds.  Notice that each compound is made of a combination of different elements.

                  Salt                                                                      Sugar (sucrose)

NaCl -elements Sodium (Na) & Chlorine (Cl)                       C12H22O11 - Carbon (C), Hydrogen (H), & Oxygen (O)

                                                                                                                           Sulfuric Acid

      Baking Soda

                                                                              H2SO4 -elements Hydrogen (H), Sulfur (S), & Oxygen (O)

 CHNaO_{3 --Carbon (C), Hydrogen (H), Sodium( Na), & Oxygen (O)}

Mixtures:

Mixtures are made up of different compounds and/or other mixtures. The mixture's substances can be removed from the mixture physically, unlike in compounds which can only be broken down chemically.  Mixtures can be Homgenous (have the same uniform appearance and composition throughout) or Heterogenous (have visibly different substances thought them).

               Milk                              Air                                         Salad                           Granite (rock)