Tuesday January 11 , 2011

1. TuesdayJanuary 11, 2011 • (Review for Semester Final Exam – Day 4)

2. Bell RingerTuesday, 1-11-11 No Bell Ringer Today.

3. Announcements Please remember these two important points: You cannot remediate your semester final exam. After the first semester ends, you cannot go back and improve your grade on any six-weeks of the first semester.

5. Review for Semester Final Exam Day 4

6. 31 To determine the Lewis Dot symbol for any element in the s-block or the p-block, simply follow these guidelines: • Group 1 elements have 1 valence electron, so only 1 dot is put around their symbols. • Group 2 elements have 2 valence electrons, so 2 dots are put around their symbols. • Group 13 elements have 3 valence electrons (13-10), so 3 dots are put around their symbols. • Group 14 elements have 4 valence electrons (14-10), so 4 dots are put around their symbols. • Group 15 elements, 5 dots. • Group 16 elements, 6 dots. • Group 17 elements, 7 dots. • Group 18 elements, 8 dots.

7. 32 When a chemical formula begins with H (hydrogen), the compound is usually an acid. If the formula also ends in O (oxygen), it is an oxyacid. Between the H and the O, there will be a non-metal, from which the acid takes its name. Examples include: HNO3 nitric acid H2SO4 sulfuric acid H3PO4 phosphoric acid

8. 33 When determining the chemical formula for an ionic compound made from two polyatomic ions, follow the procedure shown in the following example: ammonium phosphate NH41+PO43- cross the oxidation numbers: (NH4)3PO4

9. 34 The Group 1 alkali metals (lithium, sodium, potassium, rubidium, cesium, and francium) have the following properties: they are grayish in color when they are cut, they show a shininess inside like most metals, they are malleable (able to be formed into flat sheets) they are very reactive when dropped into water; they fizz, spark, give off a white vapor, or spark tiny flames when put into water, they produce an alkaline solution (hence the name), and give off hydrogen gas (the aforementioned vapor)

10. 35 Recall that you can separate the components of a mixture by physical methods, like magnetism, filtering, and boiling (remember our Lab on mixture separation.) There are two types of mixtures: homogeneous and heterogeneous. Homogenous mixtures contain very tiny solute particles that are all the same size. Heterogeneous mixtures, on the other hand, contain much larger particles that are of different shapes, sizes, and/or colors.

11. 36 Scientists’ knowledge of the structure of an atom has progressed over the years. Here is an overview of the different atomic models from earliest to most recent: When the atom was first discovered, scientists believed that it was a solid sphere, like a pool ball. It was then discovered that the outer region of an atom is mostly empty space, and that extremely tiny, negatively-charged particles called electrons whirl about this outer region. It was believed that the electrons moved about randomly. The outer region was named the “electron cloud.” Scientists then believed that the electrons where placed throughout the cloud, similar to the way blueberries are placed throughout a blueberry muffin. It was finally determined that the electrons could only occupy fixed orbits within the cloud, which allowed scientists to understand that the electron cloud had a definite structure.

12. 37 Physical properties of matter are classified as intensive or extensive. Intensive properties do not depend on the amount of matter present – these properties include color, melting point, boiling point, density, and ability to conduct electricity and heat. Extensive properties do depend on the amount of matter that is present - such properties include volume, mass, and the amount of energy in a substance.

13. 38 Some chemicals used in the laboratory can be hazardous. Here are some examples of symbols used to identify these materials: Pressurized

14. 39 What is the mass of the object being measured on this triple-beam balance?

15. 40 Boiling point is defined as the temperature at which a liquid vaporizes into a gas. In other words, if the material is below its boiling point, it will exist as a liquid. If it is above its boiling point, it will exist as a gas. Room temperature is considered to be about 72o F. For example, if a liquid material has a boiling point less than room temperature, it will be a gas at room temperature.