Check out the blackboard. That box on the left has all of the information you need to know about one element. It tells you the mass of one atom, how many pieces are inside, and where it should be placed on the periodic table.

In the next section we're going to cover electron orbitals or electron shells. This may be a new topic to some of you.

# Electrons In The Shells

Take a look at the picture below. Each of those colored balls is an electron. In an atom, the electrons spin around the center, also called the nucleus. The electrons like to be in separate shells/orbitals. Shell number one can only hold 2 electrons, shell two can hold 8, and for the first eighteen elements shell three can hold a maximum of eight electrons. As you learn about elements with more than eighteen electrons you will find that shell three can hold more than eight. Once one shell is full, the next electron that is added has to move to the next shell.

So... for the element of ALUMINUM, you already know that the atomic number tells you the number of electrons. That means there are 13 electrons in a aluminum atom. Looking at the picture, you can see there are two electrons in shell one, eight in shell two, and three in shell three.

# Aluminum Trifluoride

Fluorine (F) can also bond with aluminum (Al). Aluminum has three extra electrons and will easily let the fluorine atoms use them. Because aluminum has three, that means three fluorines can bond. The make the formula AlF3, also known as aluminum trifluoride. Each of the fluorine atoms gets an electron to fill their shell, and the aluminum loses three, giving it a filled shell too (remember, aluminum has three extra electrons). The name trifluoride means three fluorine atoms are involved.

# Aluminum Trichloride

Chlorine (Cl) can also bond with aluminum (Al). Aluminum has three extra electrons and will easily let the chlorine atoms use them. Because aluminum has three, that means three chlorine atoms can bond. They make the formula AlCl3, also known as aluminum trichloride. Each of the chlorine atoms gets an electron to fill its shell, and the aluminum loses three, giving it a filled shell too (remember, aluminum has three extra electrons). The name trichloride means three chlorine atoms are involved.

# Aluminum Phosphide

Aluminum (Al) and phosphorus (P) can also bond. Aluminum happens to have three extra electrons. Luckily, every phosphorus atom is looking to gain three electrons. It's a perfect match! Something to notice though, look how they have a bond with six electrons. That bond is known as a triple bond. When a bond has two electrons it is a single bond. When a bond has four electrons it is a double bond. Well take a look at the dots and see what a triple bond looks like!

- Chem4Kids: Periodic Table
- Chem4Kids: Atoms
- Chem4Kids: Compounds
- Chem4Kids: Electrons
- Chem4Kids: Boron
- Chem4Kids: Chemical Bonds
- Geography4Kids: Electromagnetic Spectrum