Thursday January 6, 2011 (Review for Semester Final Exam – Day 1)

A.an ice cube melts into liquid water B.a pan of water boils C.water vapor condenses on the outside of a glass of iced tea D.hydrogen gas and oxygen gas react to produce water Which of the following is a chemical change?

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.

Assignment Currently OpenPage Date of Notes on Website Date IssuedDate Due Section Review /1511/16 TEKSCheck #2 11/16 Quiz – Ionic vs. Covalent Bonding 11/16 WS - Dot Notation and Lewis Structures 11/1711/19 WS – Ionic Bonding 11/1811/30 Chemical Bonding Review 1 11/1912/3 WS – Building Ionic Compounds 11/3012/7 Quiz – Building and Naming Ionic Compounds 12/2 WS – Building and Naming Molecular Compounds – Part 1 12/912/16 WS – Building and Naming Compounds 12/1012/17

Review for Semester Final Exam Day 1

1 You must know the difference between a physical change and a chemical change. When a physical change occurs, the chemical identity of the material does not change. For example, when an ice cube melts, it’s still water. All phase changes (melting, boiling, condensation, freezing, etc.) are physical changes. When a chemical change occurs, the chemical identity of the material does change. For example, when sodium metal and chlorine gas react, the product, table salt, is a completely different substance.

2 The term “halide” refers to an ion that is formed from one of the halogens. Can you find the halogens on the Periodic Table? Name the four halogens. fluorine chlorine bromine iodine Name three metal halide compounds. sodium chloride calcium fluoride potassium iodide

3 Mass is an indication of how much matter is contained within a material sample. For example, if a ring has a mass of 24.5 grams, that is the total mass of all of the atoms in that ring. Mass is reported in units of grams, milligrams, kilograms, etc. Volume is a measure of the space that a sample of material occupies. For example, if a cube has a volume of 8 cm 3, it occupies that volume of space in the classroom. Volume can usually be equated with size: the larger the size of an object, the greater its volume. Volume can be reported in units of liters, milliliters, cm 3, etc.

4 Remember that elements in the same vertical group on the Periodic Table share similar physical and chemical properties. Notice also that as you go down a group on the Table, the atomic mass of the elements in that group increases. For example which element has properties similar to chlorine and bromine but has a lower atomic mass? fluorine

5 Usually, if a group 1 alkali metal or a group 2 alkaline earth metal bonds with a group 17 halogen, a transfer of electrons takes place and the bond will be ionic in nature. This is because the electronegativity differences between these metals and the halogens in usually greater than 1.7. The resulting compound will have properties different from those of the elements that bonded to make it. For example, sodium is a highly reactive metal, while chlorine is a toxic gas. When they bond to make sodium chloride, it is safe enough to sprinkle on you food (table salt.)

6 Metallic bonding occurs with metals because of the loose nature of valence electrons within metal elements. If two or more metals are melted, mixed together, and re-solidified, an “alloy” is created. An alloy is a mixture of two or more metals. For example, brass is an alloy of copper and zinc, and it, of course, exhibits a metallic bonding structure.

7 If a solid material is heated to a sufficient temperature, the solid will usually melt to a liquid. If heating continues, the liquid will evaporate into a gas when the vaporization temperature is reached. When materials are heated, they therefore lose a bit of mass if gas particles escape due to evaporation.

8 A material is considered to be a “fluid” if it is in either the liquid or the gas phase. Liquid particles can easily flow, or slide past one another. Gas particles are flying around their container and frequently collide with one other. Solids are not fluids because their particles are held tightly in fixed positions and are not free to slide past each other or collide with each other.

9 All chemistry students know that animals on the planet Earth breathe oxygen. What some do not realize is that the oxygen we breathe is not elemental oxygen, O. Instead, we breathe molecular oxygen, O 2. O 2 is a “diatomic” molecule, which means that two oxygen atoms are bonded together to form the compound oxygen gas.

10 Thomas Rutherford discovered the small, compact region of the atom known as the nucleus. He used his famous gold foil experiment (sometimes called the alpha particle experiment) to make this discovery. Rutherford shot positively-charged alpha particles through a thin sheet of gold foil. He noticed that some of the particles passed straight through the foil, but some were deflected. This indicated that the deflected particle were passing close to, or actually striking, a small core of positive charge – remember that like-charged repel. He concluded that there was a very tiny, positively-charged region at the center of an atom, which he called the nucleus.