2/7/11

Announcements: Study for upcoming quizzes. if you missed Friday's(2/4/11) quiz, make that up as soon as you can!

Homework: journal page 27 #2, 29, 30, & 31

Today we learned more about limiting reactants; what they are, how to find out which one is the limiting one between two reactants, and also, a little more on how to draw the reaction with the product and its excess.

A limiting factor is something that you only have a limited supply, and then have a greater amount of something(s) else, so you can only make a certain amount of the product.

To find the limiting factors, its exactly the same as Stoichiometry, you are just take it one step farther because you are searching for something different in the end. but as a review, you must convert two different reactants into one common reactant. So to start, you will sometimes or usually have one reactant in its state of mass, you then convert it into moles, followed by moles of the common reactants. Sometimes, from here you can convert to the mass, but it really depends on the following question. You then do the same thing to the second reactant, so you should have two equations in the end. Finally, you get your two usual outcomes, just like Stoich, but with those two answers you decide which one is smaller, and the reactant that you started that equation, with the smaller answer, is the limiting reactant.

Below is a picture of an example that shows this process with actual reactants.

Since 0.065 is smaller than 0.5, that makes O2 the limiting factor

Here are some more examples of limiting reactants we did in class.

For drawing out a limited reaction, you start with the equation you are given and the two reactants that you need to determined which is the limiting reactant. You draw out your given amounts of each, and then pair them up for the out come. Which ever one does not have excess, that is the limiting reactant.

This is a picture to help show a drawn out version of limiting reactants.

NEXT SCRIBER: Alyssa P

Wednesday 9/29/10

Modern View-electrons can be in ground or excited states and can jump between levels. When electrons drop levels (high to low) they give of a beam of light! Its like bees in a beehive and bees are electrons moving around the nucleus like a cloud. Similar to the picture above

Niel Bohr from 1914 discovered that electons(-charge) "ORBIT" around positive nucleus in different- ORBITALS(levels). Electrons can jump up and down these levels. As seen above.

Rutherford discovered all atoms have tiny positive centers(nucleus).

Ernest Rutherford from the early 1900's shot alpha particles(+ charge) through gold foil as shown in the picture above. Most of them went through but some deflected and these some were - charged particles!

Joseph John Thomson or J.J. from 1897 studied cathode ray tubes. He would excite the gas in the tubes with electricity. He would hold a magnet to the sides of the tube noticing a bend in the light (+ side attracted beam, - side repelled beam). He discovered that atoms must have a negative(-) charge and if that, then with overall neutrality, they must also have a positive(+) charge. This is demonstrated in his model above.John Dalton was an english schoolteacher from the early 1800's. He thought that each element was mad of elements, an atom of one element would be identicle to an atom of the same element. Also atoms do not include the existence of the nucleus, dosen't explain the existence of ions or isotopes, and dose not talk about subatomic particles (electrons, protons, and neutrons). His view of the atom looked something like the picture above.

Today we started off class by finishing the notes from yesterday on the Atomic scientists (Dalton, Rutherford, Thomson, and Bohr). You may look at yesterdays scribe for what they look like and foe more help.

After that Mr. Paek gave a lecture on the four scientists, their major contributions, what they discovered about the atom, and their actomic model. As shown above^ NOTE: start from the bottom picture and read up!!

no homework! lab test due by next friday!

Next Scriber: Maddy M.