with Dr. Doumit

The Explosion 2H2 (g) + O2 (g)  2H2O (g) An example of a combustion reaction! Hydrogen Balloon ignited by a flame.

Properties of Copper Pennies are coated with copper. Which are physical properties of copper and which are the chemical properties? What are two additional properties? Observing Chemical Change

Breaking and Making Bonds Describe what happens to the bonds in each of the steps as oxygen reacts with magnesium. Observing Chemical Change

Describing Chemical Reactions Chemical Formulas The formula of a compound identifies the elements in the compound and the ratio in which their atoms or ions are present. What are the missing chemical formulas in the table?

Modeling a Chemical Equation Like a skateboard, a chemical equation has a basic structure. How many complete skateboards can be made from the parts pictured? Describing Chemical Reactions

Molecules of nitrogen (N 2 ) and hydrogen (H 2 ) react to form ammonia (NH 3 ). How many H 2 and N 2 molecules are needed to yield two molecules of NH 3 ? Describing Chemical Reactions

Balancing Chemical Equations What are the four steps in balancing chemical equations? Describing Chemical Reactions Step 1 Step 2 Step 3 Step 4

Describing Chemical Reactions Types of Reactions What is each type of reaction represented?

Activation Energy A chemical reaction needs a push to the “top of the mountain” to get started. Where has enough activation energy been added to start the reaction? Controlling Chemical Reactions

Graphs of Exothermic and Endothermic Reactions Each of the graphs shows the amount of energy before and after the reaction. On each graph, determine whether energy is absorbed or released. Controlling Chemical Reactions

Catalysts Adding a catalyst speeds up a chemical reaction. How would the energy graph change for the same chemical reaction if a catalyst were used? Controlling Chemical Reactions

Crookes Tube (Cathode ray tube) Deflection of electrons on a magnetic field.

If a magnetic field is placed across the beam (with the north pole indicated by tape in front), the beam is deflected downward as shown (by Steve Grabowski) in Figure If the magnetic field is reversed (so that the north pole is in the back) the beam is deflected upward as shown in Figure

Why it Works A magnetic field does not exert a force on a stationary electron. However, a magnetic field does produce a force on a moving electron. The electron's motion, the magnetic field, and the force are all at right angles to each other.

The Point Properties of the electron can be determined by observing its behavior in electric and magnetic fields. The electron is negatively charged. The force produced by a magnetic field on a moving beam of electrons can be described by the right-hand rule, in which the thumb indicates the direction of the force, the index finger indicates the direction of the motion of the electrons, and the rest of the fingers indicate the direction of the magnetic field. Careful analysis of electric and magnetic fields on an electron beam determines the charge to mass ratio of the electron.