Electronic Configuration of Silicon

Ah, the good Ol' Periodic Table of the Elements. Thought finishing Chemistry class would be the end of this bad boy? No way. It's a useful tool for many, many professions.

The electronic configuration of an atom lists how many electrons are in each of its electron orbits. The outer shells are particularly important to an electrical engineer.

Let's look at Hydrogen, or H on the chart. It's electron configuration would be 1s^1, for having one electron in its outer shell (also it's only shell). Helium would then be 1s^2, filling up that first orbit. Those elements with full orbits are often called Noble Gases because they're highly stable (they don't crave any electrons because their outer shell is full, so they're less likely to bond with other elements spontaneously).

Moving on to Lithium, we have 1s^2 2s^1, meaning it's first orbit is full, and its second orbit has one electron. Other elements can be written in shorthand (because we often just care about the free electrons in the outer shell) using the noble gas preceding the element on the periodic table. This shorthand looks like this:
[He] 2sd^1

A nice chart labeling all the different letters for different orbits:

So, Silicon would be 1s^2 2s^2 2p^6 3s^2 3p^2
or simply [Ne] 3s^2 3p^2

These places have some great charts or lists for quick look-ups:
http://www.chemicalelements.com/show/electronconfig.html
http://www.science.co.il/ptelements.asp