Name:_______________________________________
Period:______
WS 5.5
Electron configuration and orbital notation self test Chemical behavior is determined by electron position. It’s a simple statement, but it says a lot. Another way of saying it is “Chemistry is all about where the electrons are”. That’s why we’ve been spending the last week focusing on electrons. However, somehow it always seems to bog down in some weird world of 1s2 2s2 2p6, and the Pauli Principle, and we forget our goal: if we know where the electrons are we know how the substance will behave. Why Neon is stable, and sodium is very unstable, and in fact why all the elements and the substances they form behave the way they do. Let’s pick an element. We know that oxygen contains ___ protons. And since it is not charged, it contains _____ electrons. We know that ____ of the electrons occupy the first shell, and the other six are in the second shell. We know that the first shell consists of a _____ orbital that holds _____ electrons, and so we say that the electron configuration of that first shell is 1s2. For the second shell we have six electrons, and we have learned that the first two will occupy a ____ orbital, and the next four go into ____ orbitals. Thus the electron configuration of oxygen is____________________. We can go into more detail, and show the exact orbitals that the electrons are in, which even show the direction the electrons are spinning in. An atomic orbital is simply a ______ of electrons, and the Pauli Principle tells us that electrons prefer to pair up with _________ spins. The first shell of oxygen contains one orbital, which we draw with a box like this:_______, showing that the electrons are paired up with opposite spins. The second shell begins with one more orbital for the two electrons of the 2s subshell, for a total of four electrons so far. We have ______ more electrons in oxygen, and they will occupy the three p orbitals. We remember to apply _________’s rule and spread these electrons out as far as possible in those three boxes. Thus we can draw the electron configuration of oxygen with its orbital notation right above it:
Note that this tells us that oxygen has four electrons in its outer (second) shell, and the two of them are unpaired….we also know from HONC that oxygen likes to form two bonds…a coincidence?? Let’s work out the electron configuration of nitrogen and see if we get three unpaired electrons: Nitrogen has _____ electrons, so the electron configuration with orbital notation is (be sure to spread out your p electrons): Does this orbital notation show 3 unpaired electrons?? If this makes sense, continue to the “how to ace it” guide.. If not, see me so we can do more examples. 23