Friday, February 1

We started todays class with the lab that we had started on Thursday. In this lab we were to carefully observe the line spectra of four unknown elements and to identify the four elements by comparing their line spectra to those of known elements. Mr. H told us about a website, http://astro.u-strasbg.fr/%7Ekoppen/discharge.html, where you can compare your spectra with the elements online.

After that we spent a few minutes going over the blog from Thrusday the Brooke did.

Next we started working on page 3 from the packet. Before we began, Mr. H warned us that this unit was going to be on of the most difficult units because it is the hardest to visualize.

The Quantum Mechanical Model of the Atom

Features of the Theory:

· Very mathematical

· Electrons are located in regions of space know as orbitals

· Each individual electron of an atom is described by 4 quantum numbers

· Each orbital holds at most 2 electrons

As we went through the rest of page 3 we added that information to our notebooks as well. The main idea was that each individual e- is described by four quantum numbers, which are n, l, ml, and ms. The first number is the principal quantum number. It is represented by the letter n, describes the energy level and size, and has the possible values of 1,2,3,… The second quantum number is represented by the letter l and determines the shape of the orbital. The quantum numbers n and l are related; l can take on any integral value starting with 0 and going up to a maximum of (n-1). This means that the possible values are 0, 1, 2, …, (n-1). Each principal energy level is has one or more sublevels. These sublevels are denoted by the second quantum number. In general, in the nth principal level, there are n different sublevels. Another method is to use the letter s, p, d, or f to indicate the sublevels l = 0, 1, 2, or 3. Each sublevel contains one or more orbitals, which differ from one another in the value assigned to the third quantum number, ml. This quantum number is used to describe the spatial orientation of the orbitals. For a given value of l, ml can have any integral value, including 0, between l and –l. The fourth quantum number, ms, describes the direction of electron spin. The ms value doesn’t describe the orbital; it describes the electrons in the orbitals. There are only to possible values for ms, +1/2 and -1/2.

After finishing those notes Mr. H instructed us to continue on to page 4.

The ways to remember orbital types:

Smartà spherical

Peopleà pinched cylinders

Don’tà dorky

Failà frog-shaped

(see chart below)

Lastly Mr. H said that we are learning about this stuff because it explains the line spectras and the elements in the periodic table, even the 14 that came after 1926, which Mr. H thinks is cool in a geeky way.