Reminder
When we last left off, we were comparing arrangement of electrons to stadium seating. If an element has all the seats in the row filled with none left over, that element is going to be stable. It will be most like other stable elements. Those are grouped together in the right-hand column on a periodic table. They are called noble gasses.
 | 8 in third shell |
| 8 in second shell |
| 2 in first shell |
Noble Gasses
|
Elements that have a whole row filled are happy. They're so happy they don't need anyone else. They don't want to give electrons away or get any new ones. Because they are loners and too full of themselves to hang out with the other elements, they are kinda like royalty, or nobility. These are known as the noble gasses. Helium is one noble gas you may know. It is non-flammable and stays in gas form. You could put it with acids or run electricity through it and it wouldn't blow up or change or anything. This is because noble gasses are happy just the way they are. Neon is another noble gas. You could run electricity through it and it would make a pretty glow, but nothing else. If you look at the atomic numbers of the noble gasses and look at those rows of stadium seats, you'll notice a pattern. Row one has two seats, and helium is number two. If you add the first row plus the second row, you have the number ten, the same as neon. Add another 8 and you have eighteen, the number of argon. The noble gasses are noble because their electron rows are filled. |  |
Families
Columns on a periodic table are called families. This is because they have similar traits. You've already met the noble family, but we're going to meet a few others.
Some families are naturally giving. They will even give when nobody wanted them to give anything. This would be like family number 1 on the periodic table. More about them in a moment. Some families are greedy takers. That would be like family 17 on the periodic table (7A). Some families are all metals, some are all gasses, but families share traits with other members of the family.
Look at element number 29. That's copper. It is in the same family as #47, which is silver, and #79, which is gold. All of these are metals with very similar properties. And all of them are found at Olympic medal ceremonies. Now that's a successful family!
The main trait that all elements in a family share is the same number of electrons in the outer orbital. In English, that means that their stadium seats look alike. Family #1 has one lone electron in it's outermost row. #2 has two electrons, and so forth. These electrons are what help make bonds with other atoms.
Family 1 - The Violent Givers
The first column down contains hydrogen, lithium, sodium and other elements. This family has one electron too many to be stable. They're pretty desperate to give up that electron. Because they're only one elecreon off from being noble, they react violently to give that electron away. Because they're not stable alone, you'll always find them paired up with another atom. If by chance you ever do find them alone, be afraid! Sodium (not salt, which is sodium chloride) has ripped water apart to give away the electron. Potassium will do this with so much enthusiasm that it can catch on fire when placed in water!
Family 2 - A little less violent
The second column down are also givers. They have two electrons in the outermost orbital so they can give two electrons away. This actually makes them more stable than their family #1 neighbors. Because they have two in their outermost orbital, those two keep each other a little bit balanced. It's further away from being noble, so it doesn't try as hard. You might recognize magnesium and calcium in this group.
Family 17 (7A), Violent Takers
While some families are generous and giving, other families are takers. This family is the column next to the noble gasses, and the closer something is to being noble, the more desperately it tries to become noble. These elements almost have their orbital filled, but are one electron short. This means they'll take that electron from anything they can find.Members of this family include fluorine, chlorine, iodine and others. Members of this family are rarely found alone. Often they hang out in pairs because they're a bit more stable that way. Because they're so unstable though, many of these are somewhat toxic alone.
Family 16 (6A), less violent takers
Like family 2, this group is less violent than it's near noble neighbors. It forms bonds easily, but tends to be less violent about it. It is two short of complete, but seems better at coping with it. Oxygen deals with this shortage by hanging out with other oxygens.
Families in the middle - dealing with disappointment
The other families are even further away from being noble. Family 13 (3A) has 3 too many, family 15 (5A) has three too few, and family 14 (4A) has four too many... or is that four too few? At any rate, only half of that back row is filled up. This means that these elements bond easily. They can take or can give electrons, and they aren't too picky about how they'll bond. This is a great thing for life, because carbon (#6) makes bonds easily because of it's family nature. Carbon is the basis for all life on earth.
Ions - The atom's way of coping with imperfection
Because not every element is fortunate enough to be a noble gas, they have to get rid of extra electrons or take extra electrons from another atom. Let's look at lithium, which is #3 on the periodic table. It's first orbital is filled. That's good, but it has one spare electron which is forced out into the second orbital. Three's a crowd for electrons, and the lithium would be much more stable if that little electron just went away. If it goes away, the atom has more protons than electrons, so it becomes positively charged. Any atom with a charge, either positive or negative, is called an ion. It's easy to figure out what ions different elements will make. All of family #1 has one too many electrons, so when it gives that electron away, it will have a charge of +1. (Givers are usually positive, even the violent givers.) Family #2 will end up with a charge of +2 because it gave away 2 electrons. Family 17 (7A) will steal one electron, becoming a -1. Family 16 (6A) will steal two, becoming a -2 ion. (Stealing is a negative thing!) What about those in the middle? Well, carbon can be considered a +4 or a -4.
When an atom becomes an ion, we need to write that down. When you separate salt into sodium ions and chlorine ions, it will separate like this:
This shows that even though the atoms have separated, the electron went with the chlorine. Here's another example:
Now that I've confused you, here's an easy way to think of ions. If it has a charge, it's an ion. So when you see + or - at the top right-hand corner of a chemical symbol, you can bet it's an ion.
Coming up next, reactions and formulas.
Or you could return to "Reading the Table."