You have just learned that you have to take that most dreaded subject of all as part of your academic program. “CHEMISTRY.”
What will you do? Change your Major or program? Hire a tutor? Run away…???
Hi, I’m Ron P. and I’m a tutor here on Wyzant.
Please join me as we discuss how to answer one of the most elementary (pun intended) questions in the science of Chemistry.
“Which is the lightest element in the periodic table?”
While this question may seem simple to answer, it actually demonstrates the use of one of the most basic, yet most important skills used in the subject and science of Chemistry.
Chemistry seems to be one of the most daunting and intimidating subjects for HighSchool and Undergrads to attempt to tackle. This is probably because of the perceived intricacies involved and all of the memory required to master the subject.
Certainly, if a person attempts to master the subject of chemistry through rote memorization the task would be quite arduous, if not insurmountable for all except those gifted with an eidetic memory. Even then, would that person have a thorough “understanding” of the material that was memorized?
Yes, chemistry does require some memory. But what if I told you that there is a way that the memory requirements can be reduced a bit? What if I told you that there is actually a “key” that leads chemists to many (not all) of the answers that they might ask throughout their academic and professional careers? Would that be of some help?
This key is sort of like a secret key or “cheat” code in your favorite video game, that helps you successfully navigate to higher levels in the game. The difference is that the chemistry cheat code is actually something that is available in most science classrooms, textbooks, and online. It is available to everyone. In fact, the use of this key is highly encouraged.
This being said, let’s dig into it.
The “key” that I am talking about is the Periodic Table of Elements. While there are a number of different versions to the Periodic Table, the differences are largely how the information is being presented. Valid Periodic Tables will, for the most part, provide the same information, and be arranged according to the same set of rules and convections.
As can be seen in the image below, the table contains a lot of information. It may seem like all of that information has no apparent organization, but the truth is that it’s quite well organized. The key is to understand how and why the information is organized in this manner. From that understanding, you can understand how to unlock the “secrets of the table.”
While there are many things you will want to learn about the table, and how to use it properly, there are a few basic facts that you will need to understand in order to get started. These “basic” organizational elements will also help you to answer our original question.
While the history and development of the Periodic Table of Elements is quite interesting, that history is beyond our current discussion. Suffice it to say that although many scientists have worked on its development, Dmitri Mendeleev is usually credited with its invention.
The current table contains 118 known elements (more or less) and is being regularly reviewed and updated. While elements may be added, and new information about known elements may also be added, the basic organizational rules and conventions remain the same.
The table not only provides important information about each specific element listed but also allows users to recognize “trends” in the properties of the elements with regard to ionization energy, atomic radius, electronegativity, reactivity, etc.
What we are primarily interested in is the basic information the table provides (directly) about each of the various 118 elements. The first 3 properties about the table that should be evident are:
1. The table is organized into columns (vertical) and rows (horizontal).
2. Elements are listed in order of increasing atomic number (number of protons in the atomic nucleus).
3. The columns and rows form cells (boxes) into which vital information about a specific element is written.
Along with these three properties, we will also need to know a few Terms or Definitions in order to understand what we are talking about.
Definitions:
Atomic Number – the number of protons in the nucleus of an atom of the element. The number of protons defines the element and determines its chemical behavior.
Atomic Symbol – the abbreviation chosen to represent the element.
Atomic Weight – for naturally occurring elements (1 thru 92) the atomic weight is the average mass of the isotopes of the element and is represented in atomic mass units (AMU).The atomic mass is a weighted average of all of the isotopes of that element, in which the mass of each isotope is multiplied by the abundance of that particular isotope.
For elements 93 thru 188 (which are not naturally occurring, but created in a lab) usually, the atomic weight of the longest-lived isotope is listed.
While there are more properties and conventions in the Periodic Table, these three are a good place to start, and they will allow us to answer our initial question.
1. If you look at the table you notice that it is organized into 18 columns called “groups” and 7 rows called Periods.
a. Groups (columns) contain elements with the same number of “valence electrons” which are located in the outermost shell or orbital and are the electrons that are taking part in chemical reactions.
b. Periods (rows) contain elements with the same number of atomic shells (orbitals).
This arrangement allows the user to predict how, and with what other elements each might react or combine.
2. If you look at the table you will notice that the elements are listed in order of increasing Atomic Number, starting with Hydrogen (1) in the upper left-hand corner and running to Oganesson (118) in the lower right-hand corner.
a. There is a relationship between Atomic Number and Atomic Weight (Mass). You may notice that as Atomic Number increases so does Atomic Mass.
3. Each element and its vital information is listed in its own cell or box. The information listed usually includes Atomic Symbol, Atomic Number, Atomic Weight (mass), and often the Name of the element.
Now that we have discussed these three characteristics of the Periodic Table of Elements we can at last return to our original question:
Which is the lightest element in the periodic table?
With your new knowledge and a quick look at the Periodic Table of Elements, you can easily determine the lightest element.
So, you can see that the Periodic Table of Elements truly is the “key” to unlocking the secrets of the science of Chemistry.” It has many other characteristics which allow the student and scientist to unlock even more useful information about the elements. For the one who masters its secrets (skills), the table can be a very powerful tool indeed.
If you wish to learn about the table or to study it in-depth, you can explore the American Chemical Society (ACS) website. I have provided their information in the Reference section below. Or, you can schedule a tutoring session with me, here on Wyzant.
And remember – “You can do this.”
Sincerely
Ron P.
