Remember that according to the Aufbau principle electrons are added to low energy orbitals first and then, as the low energy orbitals are filled up, electrons go into higher and higher energy orbitals. Group 1A (IA) Elements Have One s Electron Later we'll take a look at how elements in the same row are related.
In this section, for example, you'll learn that elements in the same column of the Periodic Table have similar chemical properties. It turns out that the shape of the Periodic Table actually helps to tell us about the chemical properties of the different elements that exist in our world. Now, what's the first thing you thought when you saw the Periodic Table? If you're like most people, the first thing you thought was probably something like, "Wow – that's a funny shape! Why is the Periodic Table shaped like that? Why is it lower in the middle? Why is it higher on either end? Why is there that odd-looking disconnected piece at the bottom? The Periodic Table doesn't look like a table at all!" In this chapter, you'll begin to see why the Periodic Table has such a funny shape. In this lesson, you will learn why the Periodic Table (as shown below) has such an unusual shape.
Scientists use the Periodic Table to summarize information about all of the known elements that exist in our world. Finally, you have seen examples of the Periodic Table. Hydrogen has 1 proton (and 1 electron if it's neutral), helium has 2 protons (and 2 electrons, if it's neutral), and lithium has 3 protons (and 3 electrons, if it's neutral). And you have learned that atoms of different elements have different numbers of protons. Remember, you have learned that there were 118 different kinds of atoms, and that each was known as an element. We're finally ready to discuss the chemical properties of the simplest chemicals out there – we're finally ready to discuss the elements. It probably seems like all we've been spending a lot of time learning about protons… and neutrons… and electrons… and electrons… and more electrons… so you might be wondering – when do we actually get to study chemistry? When do we get to study reactions? When do we get to study explosions? When do we get to study plastics, and medicines that can be made by combining different kinds of chemicals? The answer is now. 4 Group 4A-8A Continue to Add p Electrons to the Outermost Energy Level.3 Group 3A (IIIA) Elements Have s and 1 p Electrons.2 Group 2A (IIA) Elements Have Two s Electrons.1 Group 1A (IA) Elements Have One s Electron.