Elements and the Periodic Table

Everything that you see around you is composed of one or more of the known elements. But what are these elements?

An element is a fundamental substance that can't be broken down further through chemical or physical means. This means that there is a base unit of elements, ans that is the atom. Atoms cannot be chemically changed, and are the tiniest unit of an element. We'll talk more about atoms in a later post.

What we're focusing on here, is being able to read the periodic table of elements.

Every element has it's own atomic symbol. Some match up well to the English names, and some don't make much sense at all. The ones that don't make much sense are usually passed down from their Latin names. Here are some elements and their symbols.

Element Name              Element Symbol
Carbon                         C
Argon                           Ar
Cobalt                          Co
Sodium                         Na (from the Latin word for sodium, natrium)
Platinum                        Pt
Arsenic                         As
Potassium                     K

Notice that all chemical symbols have 1-2 letters and have only 1 capital letter. This helps make sure that you can distinguish what's inside of something and you don't mistake one or more elements for others.
Now, Let's take a closer look at the table.

You may notice that some elements are written in different colors. This indicates their state at standard temperature and pressure, that is, whether they are solid, liquid, or gas. In this table, black lettering indicates solid, yellow lettering means liquid, and white means gas.

This is Carbon. As you can see, it's symbol is C, but what do these other numbers mean?
First we'll start with the number in the top right corner, 6. This is what's referred to as the atomic number. The atomic number is unique for every element, no 2 elements share the same atomic number. "That's all fine and dandy," you might say, "but what's the point?" Well, my friend, the atomic number for every element corresponds to the number of protons in the nucleus of an atom of that element. As you can see, the periodic table is organized in ascending order of atomic number, except for the 2 rows at the bottom that have been removed to preserve groupings on the periodic table.
The other number, 12.01, is the atomic mass. The atomic mass is the weight of the atom, calculated by adding the number of protons to the number of neutrons in the atom. "But wait," you say, "how does that give us a decimal?" Elements come in different forms known as isotopes. Different isotopes of an element have different numbers of neutron in their nucleus. The atomic mass on the periodic table is the average mass of all atoms of that element. For instance, carbon has 2 somewhat common isotopes: Carbon 12 (6 protons and 6 neutrons)  and Carbon 13(6 protons and 7 neutrons). The abundance of carbon 13 is 1% of that of carbon 12.  Therefore in the average mass of carbon is more than 12, but not by much, hence the decimal.

The periodic table is organized into rows and columns. The rows are called periods and the columns are called groups. The groups are numbered across the top row of the table. The periodic table is organized in such a way that groups on the table usually have very similar properties, we'll explore this a little more in the next post.