Hey, welcome back. Today we're going to talk about electron dot formula, also known as the Lewis dot formula. Chemical bonding depends mostly on the number of electrons in the highest or outermost energy level. This level is called the valence energy level.
The electrons in the outermost energy level are referred to valence electrons. Chemists have... devise a shorthand system to indicate the number of valence electrons in the valence energy level. This is called the electron dot formula.
So if you look at a periodic table, you see these group numbers up at the top of the periodic table. So hydrogen has one valence electron, magnesium here has two valence electrons, and then we skip all of the numbers from three to twelve, and then you see that they just start at three, four, five, six, seven, and eight. So carbon has four valence electrons, not fourteen.
The most important thing when doing the electron dot formula is the order of the dots. So I have some examples here. First we'll start with lithium. If we go back to the periodic table, we see that lithium is in group 1, so it has one valence electron.
So we'll start with lithium. So that means you have one dot around your atomic symbol. So that is your electron dot representation for the lithium atom.
The next example is calcium. If you go to calcium on the periodic table, You see that it has two valence electrons. You go back here and you go one, two. You always want to make sure you're going around your atomic symbol like this. Our next example is nitrogen.
So we see that nitrogen has five valence electrons. So nitrogen, so you go one, two, three, four, and then you start going around again, five. Our last example is iodine.
So you go, you find iodine on the periodic table, and you see that it has seven valence electrons. So one, two, three, four, five, six, seven. Hopefully that helped you out with your electron dot representations.