Periodic Table of Elements

Of course, in everyday life, we're always hearing about unique elements like hydrogen, oxygen, carbon, chlorine. When it comes to our everyday schedules, it's easy to say that these elements are all very different from each other within the physical universe. After all, we breathe in oxygen and get our pools filled with chlorine. They can't possibly be similar, right? Well, you'd be surprised. It turns out that there are some very similar trends that occur between certain elements. Thus, we can't exactly say every element is unique or unrelated to other elements when, in fact, they are.

In order to make a framework for these trends and shared properties, we got the periodic table of elements. If you've taken a chemistry(or even just a science) course, you've most likely been able to see this table(pictured above). This table allows for a more easy and intuitive interpretation of the periodic trends that occur throughout all known elements in the physical universe.

Obviously, the periodic table is 2-dimensional, so it consists of rows, formally known as periods, and columns, formally known as groups.

The group on the leftmost side(starting from Li down to Fr), known as Group 1, are known as Alkali Metals. The group to its right, Group 2, are Alkali-Earth metals. Groups 3-12 on the main periodic table are called transition metals. The top period on the bottom two rows are known as lanthanides while the bottom period are known as actinides. Groups 13-16 are named by their topmost element. For example, Group 13 is the Boron Group, Group 14 is the Carbon Group, and so on through Group 16, the Oxygen Group. Group 17 are Halogens while Group 18 are Noble Gases.

If you notice the box on the bottom left of the image, that is the way to interpret each individual element "card" within the periodic table. The top left signifies the atomic number, which is the total number of protons within an atom of that element. If the atom is neutrally charged, then this is also the total number of electrons within an atom of the element the card refers to. The symbol at the center is an abbreviation of the name of the element(except for Potassium, which is abbreviated as K because P is taken by Phosphorus). Lastly, the number below the symbol is the atomic mass(mass of one element) of the element. Note that is in atomic mass units, not kilograms or grams or any SI mass unit. That should make sense because if the former was true, you'd expect every atom of hydrogen to have a mass of 1 kg, and it's safe to say that that doesn't happen.

The atomic mass is also the molar mass of the element. The molar mass is the mass(usually in grams) of one mole of atoms of that element. If that doesn't make sense, don't worry because the Stoichiometry section explains the concept of moles in greater detail.

You can get the number of neutrons in an element by taking the atomic mass and subtracting the atomic number from it. Most of the mass in an atom comes from the nucleus as the electrons are far less massive than protons and neutrons. Both protons and neutrons are about 1 amu each(this is why hydrogen which has one proton has an atomic weight of 1 amu).

When it comes to valence electrons, the periodic table can tell you everything you need. Here's the table you need to configure the number of valence electrons for most elements. Note that the group numbers on the periodic table at the top of the page are at the top.