Electron Configurations

Electron Configurations Init: 10/07/09 by Daniel R. Barnes

SWBAT . . . . . . make electron configurations

CA Chemistry Standard 1g*: Students know how to relate the position of an element in the periodic table to its quantum electron configuration and its reactivity with other elements in the table

You should already have learned by now that atoms are made mostly of . . . empty space

However, that space isn’t quite empty. There are ELECTRONS whizzing around the space surrounding an atom’s nucleus empty space However, electrons don’t orbit a nucleus exactly the same way that a planet orbits the sun. The truth is far more bizarre than that. Electrons in an atom occupy energy states called “orbitals”, but there are some serious differences between an electron “orbital” and the orbit of a planet. At any given time, a planet has a definite location in space, and it also has a definite speed and direction of motion. An electron, on the other hand, has neither. An electron merely has probabilities of being in certain locations and probabilities of moving with certain velocities.

The lowest electron energy state in an atom is the “1s” orbital. The 1s orbital is often represented as a spherical region of space. The 1s orbital doesn’t truly have an outer boundary, but we draw one anyway. 1s The meaning of the yellow line is this: When an electron is in the 1s orbital, it is 90% likely to be inside the yellow line. It has a 10% probability to be outside of this “boundary”. The essence of the 1s orbital is that the electron is more likely to be found closer to the nucleus than farther from it. This is represented by the red color being most intense in the center and fading to black toward the outside.

. . . and extremely unlikely, though still possible, to be this far away from that positive “nut” in the middle of the atom. The electron is very likely to be here, in the center, near the nucleus . . . . . . not quite as likely to be here, at a medium distance from the nucleus . . . . . . very unlikely to be here, far from the nucleus . . . The meaning of the yellow line is this: When an electron is in the 1s orbital, it is 90% likely to be inside the yellow line. It has a 10% probability to be outside of this “boundary”. The essence of the 1s orbital is that the electron is more likely to be found closer to the nucleus than farther from it. This is represented by the red color being most intense in the center and fading to black toward the outside.

The 1s orbital can only hold two electrons. The third and fourth electrons in an atom exist in the “2s” orbital. The 2s orbital is just like the 1s, only larger. 1s 2s

The 1s and the 2s orbitals don’t like next to each other. They share a common center point. Let’s superimose them on top of each other, like they’re supposed to be. 1s 2s

An atom with more than four electrons will have one or two electrons in the atom’s 2p orbitals. “p” orbitals are made of two lobes each. Some people think a p orbital looks like a peanut. 1s 2s 2p

1s 2s 2px

2py 1s 2s 2px

1s 2s 2px 2py

2pz 1s 2s 2px 2py

1s 2s 2px 2py 2pz

This is what an atom with ten electrons looks like. 1s2 2s2 2p6 Its electron configuration would be written as you see above.

With the “boundaries” erased, it looks more like this . . . It’s not exactly the neat little solar system like Rutherford envisioned, is it? Instead, it’s a hazy cloud of probability. It’s a misty ghost with an indistinct existence. 1s2 2s2 2p6

the end

Electron Configurations