Example: The Noble Gases (column 8A). The noble gases have 8 electrons in their outer shell and are very happy (or as you might say---STABLE) because of it. They have no desire to bond with any other atom. They are so happy that every other atom that does not have a full outer shell wants to be just like them.
A full outer shell means 8 electrons in the outer shell for most elements. 2 electrons in the outer shell (or first energy level) for very small atoms.
To help visualize the # of electrons in the outer shell we will use electron-dot structures.
A somewhat important atom named Oxygen (O) happens to have 6 electrons in it’s outer shell. Click to see an electron-dot structure of Oxygen. (Caution: Electron-dot structures are very artistically difficult.)
O An electron-dot structure of Oxygen (O). Oxygen is in Column 6A. It has 6 electrons in it’s outer shell so that is why there are 6 dots surrounding the chemical symbol for oxygen.
CLICK AGAIN TO SEE MORE ELECTRON-DOT STRUCTURES OF SOME OF YOUR FAVORITE ELEMENTS.
AuCa Al C As S Cl Ne Gold--Column 1BCalcium—Column 2AAluminum—Column 3A Carbon—Column 4A Arsenic—Column 5ASulfur—Column 6A Chlorine—Column 7ANeon—Column 8A (and very happy)
To gain a full outer shell an atom can either lose or gain electrons. Click to see examples with Sodium (Na.)
Sodium can gain 7 electrons from another atom to have a full outer shell. Sodium nucleus + seven electrons Sodium now has a charge of (-7).
Sodium can lose 1 electron to another atom to have a full outer shell. Sodium nucleus subtract one electron Sodium now has a charge of (+1).
Answer the following question in your head: Do you think it is easier for Sodium to have a full outer shell by gaining 7 electrons or losing 1 electron?
You are a very smart person so of course you answered, “What is— Lose one electron.” You are correct for $500 imaginary dollars. It requires less energy for Sodium to lose one electron then to gain 7 electrons.
Answer the following question in your head. You need to change the channel on the TV and the remote control is by your side. Do you get up and push the buttons on the TV or use the remote to change the channel? Why?
If you are like an atom, you use the remote control to change the channel because it requires less energy. An atom will always do what requires the least amount of energy. And now you and an atom have something in common!
Another way to look at it is to remember that atoms like stability. An atom’s first priority for stability is to have a full outer shell. Atoms strive to achieve this while only minimally disrupting other components of stability that are important, but not as important as having a full outer shell. An example of another component of stability is atomic charge. The closer to zero the atomic charge is, the more stable the atom. So, when sodium is faced with the opportunity to achieve a full outer shell by gaining 7 electrons and taking on a charge of –7, or losing one electron and taking on a charge of +1, it chooses to lose one electron in order to maximize its stability.
Question #1 (Answer in your online lab notebook) Is oxygen (O) more likely to gain 2 electrons or lose 6 electrons to have a full outer shell? O
Question #2 What will Yttrium (Y) most likely do to complete it’s outer shell? Y
Question #3 What will Flourine do to complete it’s outer shell? F 9 19
TRICK QUESTION—Think about it in your head. What will carbon (C) do to fill it’s outer shell. C
Since Carbon has 4 electrons in it’s outer shell it has many bonding options and can go either way. Perhaps this is why there is 4 times as many molecules containing carbon as all the other elements combined.
Question #4 Sodium (Na) is a nice looking bachelor who likes sports, cleaning bathrooms, singing in the rain, and has 1 electron in his outer shell. Which of the following ladies will Sodium be the most happy with? Rb Lady #1— Rubidium (Ruby for short.) Cl Lady #2—Chlorine (Has green hair.) Si Lady #3—Silicon (Very computer saavy.)
Don’t you wish match- making was that easy? Well, in the real atom world it can be more complicated than question #4. Often, more than 2 atoms join together, and there are different ways they can join.
Chemicals bonds can also be represented by dashes, observe the following: O HH OO NN Single Bond—Water (H 2 O). Double Bond—Oxygen (O 2 ) This is the form of oxygen we breath. Triple Bond—Nitrogen (N 2 )
We are going to explore ionic, covalent, and metallic bonding in the next assignment.