British Sign Language Glossaries of Curriculum Terms

BSL Chemistry Glossary - electron arrangement - Definition

This (drawing represents) is an atom and I am going to talk to you about three things:

• The first is ‘energy shell/level';
• the second is the ‘electron arrangement' and
• thirdly the ‘outer electron'.

This is an element and in this instance we've chosen ‘Argon'.

Here in the middle we have the nucleus, which contains protons and neutrons. In these outer shells there are electrons. These energy levels have different numbers of electrons - the first energy level can contain up to a maximum of 2 electrons; if there are more these are found in the next energy level, which can hold up to 8 electrons; again if there are more these are found in the next energy level which means there are then a series of energy levels. The ‘outer electrons' are found in this outermost shell, furthest away from the nucleus.

Let's have a look at another element.

This element is Lithium and here's the chemical symbol ‘Li' - let's have a look at a drawing of it. The ‘3' you can see next to the symbol (bottom left) refers to the number of protons (3) and the number of electrons (3).

Here we have a shell containing 2 electrons but what about the 3rd? That moves out to the next shell - now we can see all three.

This outer shell can contain up to 8 electrons, but it only has one which means that Lithium is very reactive with other substances. We can write this in the following way - Li 2, 1 - the 2 refers to the number of electrons in the innermost ring and the 1 refers to the number of electrons in the next ring. The ‘1' means that if you look at the Periodic Table on the first page of your Data Booklet you'll find Lithium on the far left in the first column/group and that's because it has ‘1' outermost electron.

Let's look at another example - Silicon. Here's the chemical symbol - ‘Si'. The numbers here are much larger - 28 and 14. Let's have a look at the shells/electron arrangement. The first shell as we know can only contain up to a maximum of 2 electrons, if there are more they're found in the next shell out, which can hold a maximum of 8. That's 10 altogether if we add the 2 inner ones. But we need 4 more and these are found in the next shell. Now we have all 14 and 3 energy shells with 4 outer electrons in the outermost shell. We write down this electron arrangement like this: ‘Si 2, 8, 4' Silicon has 2 electrons in the innermost ring, then 8 and then 4 in the outermost ring. If you go back to your Period Table you will find Silicon in the 4th column - Group 4.