## Sunday, October 30, 2011

### VSEPR

Valence Shell Electron Repulsion Theory

Electrons do not like each other and when looking at molecular structures - electrons and unshared electrons (the two dots paired together) will space out evenly so they are as far apart as possible.

For help with VSEPR - read this.

## Friday, October 28, 2011

### Covalent Bonding

We are practicing ionic bonding and naming and learning how to bond and name things that are covalent.

If it is a - and -, the bond is covalent. The electrons are shared in the bond. To get the formula, you have to draw the Lewis Dot structures for the elements and connect the dots that don't have friends. You write the formula based on your drawing. To name it, use prefixes to indicate the number of atoms in the formula and the second one ends in -ide. For these it doesn't matter which element comes first.

## Tuesday, October 25, 2011

### Ionic Bonding

Students learned about ionic bonding. Ionic bonding happens between metals & nonmetals (positives & negatives). The electrons are given and taken in this ionic bond. To get the formula, you criss cross the charges. To name it, you say the name of the metal, then the name of the nonmetal with an -ide ending. If it is a metal from DForP block, then you use a roman numeral to indicate the charge of the metal.

After learning the basics, students in first period practiced with an activity called "speed dating." Students were metals ("boys") and nonmetals ("girls") and practiced dating, bonding, and naming the ionic bonds they would make with their partners. The funny thing is that being a male did not necessarily make your character a "boy." :) Students really got the hang of bonding, were able to work with and help a variety of partners, and had fun. We will continue this activity tomorrow in all class periods.

Now that we understand ionic bonding, students should find this cartoon amusing.

Ionic Bonds for Dummies

Here is a cool interactive where you can build models to simulate ionic bonding.

## Sunday, October 23, 2011

### Valence Electrons and the charge of ions

Yesterday students learned about valence electrons. Valence electrons are the outermost electrons and are the electrons that are used for bonding and participate in reactions. Valence electrons are only found in the S and P blocks. The max number of valence electrons is 8. Students practiced counting valence electrons and drawing Lewis Dot Structures.

Students also practiced identifying which noble gas an element wanted to be like. All elements want to be like two noble gases - it is just a matter of figuring out which is closer. Elements want to be like noble gases because they have full outer electron shells, or full valences. This makes them stable and non reactive which is why noble gases are sometimes called the inert gases.

Today students learned how to use valence electrons and dot structures to determine the charge of an atom. Atoms either want to gain electrons or lose electrons to become like those noble gases they envy.

• Ions are atoms or molecules that have a net charge, either positive or negative. There are two kinds of ions:
• Anions are negatively charged ions because they have negative net charges. This means that there is a greater number of electrons (-) than protons (+). For example, the anion, fluoride (F 1-), has a one negative charge because it has a total of nine protons and ten electrons. Thus, the net charge for fluoride is 1 negative.
• Cations are positively charged ions because they have  positive net charges. This is due to these ions having more protons (positive charges) than electrons (negative charges). For example, calcium (Ca 2+) is a cation ion with 20 protons and 18 electrons. The net charge for Calcium is 2 positive. (from here)
Students also learned how to identify the charges of metals with more than one oxidation state using Roman numerals. Metals in the D, F, and lower P get Roman numerals - basically all metals but the S block, Aluminum and Boron get roman numerals. The roman numeral tells you the charge. We have to use this system because those odd metals can actually be found in more than one form - some with 2 possible charges - some with more than four!

## Wednesday, October 19, 2011

### Atom Models and Periodic Trands

Students made a foldable reviewing all the dudes they need to know that influenced the development of the atomic model. Students tried it out without their notes and realized how little they remembered... and then used their notes to record the information. We also watched a BrainPop about the atomic models to help refresh their memories. Now that they have their foldables made, they can use them to study for the unit test and to study for the SOL.

Periodic Trends.

Electro- negativity is how badly atoms want electrons. The most electronegative atoms are Fluorine, Chlorine, and Oxygen. Ionization energy is how difficult it is to remove electrons. It is difficult to remove electrons from atoms that are electronegative.

Atomic radius increases as you move down the periodic table because atoms have more mass, but actually decreases from left to right because atoms are holding on to their electrons tighter (because they are more electronegative).

## Monday, October 17, 2011

### Electronic Configuration

Students learned about the orbitals SPDF and what regions of the periodic table those orbitals correspond with. The letters really have to do with an intense mathematical equation used to calculate the probability of finding an electron in the electron cloud.

The D block is dumb and that's why it starts with one number lower. Really they just have less energy and have the same amount of energy as the S and P block in the 3rd period. The F block are failures and that's why they are 2 lower... or they have a lot less energy.

Students learned the pattern of electronic configuration and how to use it. Basically its like giving directions to an element on the PT using set landmarks. It is a bit confusing, but once you get the pattern, its not too bad. We practiced with SPDF and electron configuration with arrows.Students practiced identifying the energy level, orbital, and location of elements on the periodic table. For example Carbon is a 2P2 because it is in the 2nd period, in the P block, and the 2nd one over in the P block.

Students practiced a bit and then they played Battleship to practice some more. The Periodic Table became the game board and students hid their ships on it, then guessed hits using the electronic configuration of the atoms. I think they really got the hang of it because I did not field many questions at that point.

## Friday, October 7, 2011

### Atoms and the Periodic Table

Atoms, or elements, are the smallest unit of matter. They retain their identity in chemical reactions and are combined to form compounds and everything in the universe.

Atoms have some basic parts. Protons and Neutrons are found in the nucleus and make up the atomic mass. To find the number of neutrons, you subtract the atomic number (number of protons) from the atomic mass number (protons plus neutrons).

Electrons are so tiny that they do not influence the atomic mass. They are found orbiting the nucleus in shells or orbitals. Atoms are neutral so the number of protons equals the number of electrons.

Students got a sample of beans and counted the number of protons, neutrons, and electrons to see which atom it matched with on the periodic table.

Mendeleev deisgned the periodic table by looking at the properties of elements on cards and arranging them different ways until he got a system that worked. No one told him how to do it, he just did it until it worked. He even left spaces for elements that were discovered in his lifetime. (More info about Mendeleev) His periodic table was set up according to atomic mass number. The current table, altered slightly by Moseley, is organized by atomic number (number of protons).

Next we discussed regions of the periodic table, colored them, and labeled them. Periods are horizontal rows (periods go at the end of a sentence) and there are 7 periods. There are 18 groups or families (vertical columns) and a few of them have special names. This a pretty excellent diagram. This website gives a lot of helpful information.

We finished class by playing a quick game Guess Who.

## Saturday, October 1, 2011

### Endo and Exo

Today students learned about endo and exothermic reactions.

Endothermic reactions absorb heat and get warmer (End Up).

Exothermic reactions lose or release heat and get colder (Exit down).

To test this out, look at a whack-a-pack and make observations. The pack starts off at room temperature and when you hit it, the reaction occurs. This is a chemical reaction for a few reasons - one you can hear it fizzing. Two it blows up so a gas is being formed (1 of the 4 ways you know a chemical reaction has occurred). And Three there is a temperature change (another of the four ways). The pack gets really cold which means it is releasing heat and this is an exothermic reaction.

Watch this little video to see how it works. These are available at Dollar Tree at Valentine's Day if you are interested.