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What is Dalton's Atomic Theory?

 Dalton's atomic theory is John Dalton's theory on what atom's are made out of as well as  how they function when compounded, or combined. John Dalton came up with this theory in 1803, and
later Dalton's atomic theory became the foundation of chemistry, because his model displayed the basic knowledge of atoms during the 19th century very well.  Below, we have split up Dalton's atomic theory into the main assumptions that he made so that it will be easier for you to understand.
Dalton's Atomic Theory
  1. All matter is made up of atoms, which are tiny particles that are essential to making up an element.  He also used the Law of Conservation of Mass to determine that every atom is unable to divide itself as well as unable to be destroyed. Dalton also believed that they were spherical particles.

  This is a picture of what Dalton believed
 the atom to look like.  As you can see, it is
 a sphere, and it is not very complex.
    2All atoms of the same element share the same properties, or characteristics, the most   important            being  the atomic mass of the atom.  For example, any atom of Carbon has an atomic mass of12.01.


    3.  Elements can become compounds, which are created when two or more atoms of different elements combine.  When this happens, the properties of each atom change, such as the number of electrons, in order to be able to be combined with the other element.                                                   
    This is a picture of a compound.  As you can see,
    there are two "white" atoms combined with one "red" atom.
        4.  Chemical reactions are  changes in atoms that occur when atoms are rearranged, and not created or destroyed.  This shows that an element can't be transformed into another atom, and matter can't be produced or destroyed.
                                                                    Here is an example of a chemical reaction. 
                                                                    In this picture, four Hydrogen atoms and two
                                                                    Oxygen atoms are rearranged to produce two
                                                                    water molecules (two hydrogen, one oxygen)
    These two pictures (above and below) show Dalton's element symbols.  Dalton created a symbol composed  of a circle containing a different design for each element.  However, scientists decided that these symbols were irrelevent, because they didn't accurately show the structure of the element.




    For another explanation of Dalton's Atomic Theory, here's a link to a video that visually explains it - http://videos.howstuffworks.com/hsw/23467-atomic-structure-the-dalton-model-of-the-atom-video.htm