Chemistry: Elements

Chemistry: How it all goes together

The periodic table lists all the known elements (they keep discovering new ones) in rows based on how many protons there are in the nucleus, and columns that repeat every 18 since those all share the same characteristics. The number of protons in the nucleus determines the basic characteristics of each element. If Carbon has 6 protons, for instance, and you could take one away, the characteristics would change and it wouldn't be Carbon anymore, it would have the characteristics of Boron. The number of protons, plus the number of neutrons denote the atomic mass. You usually find this number on the lower left hand side of the box the element is listed in. The atomic mass, minus the number of protons gives you the number of neutrons. There must be an equal number of electrons orbiting the nucleus as there are protons. Electrons have a negative charge, which balances out the positive charge of the protons. Electrons exist in "shells" or "orbits" outside the atom, which we will not discuss here. You can look that up elsewhere as we could talk all day and write several text books on that alone!

Elements are the smallest amount of something (they are atoms) that cannot be further divided without changing into something else. They are made up of protons, neutrons, and electrons. These in turn are made up of subatomic particles, such as muons, gluons, bosons, and such. Again, we will not discuss subatomic building blocks in this text.

When atoms react with each other, or combine, they form compounds that may have completely different characteristics from those individual atoms. For instance, table salt, sodium chloride, NaCl, is a combination of a reactive (think explosive) metal, sodium, and a poison gas, Chlorine. Together they make something we all need in our bodies to survive. Some elements will not combine. This depends on how many electrons are in the outermost shell or orbit. If there is not a complete 8 electrons, the atom will seek out another atom with one to spare. They share this electron and become a new compound. Atoms such as the Noble Gases (Helium, Neon, Argon, Krypton, Xenon, and Radon) have a complete outer shell and do not react with other elements at all. Hence the term "noble" gases.

But how does this puzzle explain matter?

The elements listed in the periodic table are arranged in rows and columns. Rows repeat every 18 elements and are stacked in columns where they are most alike. For instance, the first column on the left contains all reactive metals. These can react violently with substances such as water, and can explode upon occasion given the right conditions. They are highly reactive. The last column on the right, contains the Noble Gases. These are all gases at normal room temperatures, and because they have a complete outer orbit that has the maximum number of electrons, they don't react at all. There is no Kryptonite, because Krypton can't react with any other elements to form a solid. The point is, all the elements in a column share the same characteristics. We'll go over more of that in class.

There are two types of chemical bonds (covalent and ionic), that is to say that there are only two ways elements can combine to form "compounds." Compounds are more than one element bonded to one or more other elements to form something with totally different characteristics, such as water. Water, H2O, is a combination of two gases, hydrogen and oxygen. When put together, they form a combustible compound that can be burned. (see picture on the home page of the dirigible Hindenburg burning upon landing in Manchester Township, May 6, 1937. The light gas hydrogen was used to make it float in air like a carnival balloon, but when it came into contact with the oxygen in the atmosphere, it was then an combustible compound, and it caught fire and pretty much exploded. When hydrogen and oxygen burn, they produce water. H2O, which is one hydrogen atom and two oxygen atoms. So, two gases react and giving off energy in the form of heat and then combine to form water. See also our chapter on energy.

An atom is composed of three major parts; the nucleus is made up of protons and neutrons. Protons have a positive electrical charge, and neutrons have no charge. The third part is the electron, and it has a negative charge. Electrons orbit the nucleus in rings, each of which can only hold a certain number. There must always be the same number of protons and electrons for the positive and negative charges to balance out each other. IMPORTANT: The number of protons in an atom define it's characteristics. If, for instance you could take a proton away from, say, an atom of oxygen that has 16 electrons, and you take one away, it's not Oxygen anymore, it's Nitrogen. Different dude altogether! Take 4 protons away from Radon, a gas, and it turns into lead.

The diagram shown above is very, very simplistic illustration of an atom. In this illustration, the element Helium, a lighter than air gas is represented. The red circles are protons, you can see this by the plus sign. The green ones have no sign, so they don't have a charge at all. They are neutrons, and together with protons, make up the nucleus, or center of the atom. The yellow circles are the electrons that orbit the nucleus and balance the charges of the protons (the minus sign indicates a negative, or opposite charge as the protons).

Questions to think about:

1. How do atoms combine to form compounds?

2. What exactly is compound an why do they have different properties and characteristics?

3. What are negative and positive charges? Are they electric?

4. The 3 atomic particles listed above are on the beginning. What do we call the parts that make up protons, neutrons, and electrons?

5. Other than chemistry, atoms and their combinations must obey the rules of physics, just like everything else in the universe. Why is this?