Chapter 2 & 3
A pure substance is something that is consistent throughout. This means that in this substance all the atoms or molecules are the same.
Mixtures are collections of more than one type of molecule and/or atom. This can include solutions, such as salt water, suspensions which tend to be cloudy, and mechanical mixtures, such as raisin bran where the parts are readily visible and can be separated.
Physical and Chemical Changes
Chemical change is any change that results in the formation of new chemical substances. At the molecular level, chemical change involves making or breaking of bonds between atoms. These changes are chemical changes: iron rusting (iron oxide forms) gasoline burning. Physical change rearranges molecules but doesn't affect their internal structures. Some examples of physical change are:
:whipping egg whites (air is forced into the fluid, but no new substance is produced) :magnetizing a compass needle (there is realignment of groups ("domains") of iron atoms, but no real change within the iron atoms themselves).
Tek: 4.A, 5.A, Youtube.com
Extensive & Intensive Property.
Solid, Liquid, & Gas.
Unit Conversion and Dimensional Ananlysis
Example (from book)- If you want to convert a temperature in degrees Celsius to a temperature in kelvins, you focus on the relationship between the units in the two temperature scales.
Tek:2.G,8.E, the chemistry book
Scientific notation expresses numbers as a multiple of two factors: a number between 1 and 10 which is raised to a power, or exponent. A simple way to sum this up is for you to take an outrageous number like (ex. from book) 1,392,000 which would be come 1.392*10^6. What I did there was I moved the decimal to the first integer and then I counted how many spaces I moved to the left to figure out what my exponent is. It's the same thing if you moved to the right, the only difference is the exponent will be negative.
When you add or subrtract numbers written in scientific notation, you must be sure that the exponents are the same before adding or subtractiing. Suppose you have (7.35*10^2m+2.43*10^2m) all you would do is add 7.35 and 2.43 and your final answer should be (9.78*10^2m). If the exponents aren't the same you would have to find the first factor that is between 1 and 10 and use that exponent. For example (2.70*10^7+1.56*10^6+1.65*10^8), you would leave the first figure alone and change the other two. On the (1.56*10^6) you would raise the power one higher so that it equals 7. On the (1.65*10^8) you would decrease the power to 7 and move the decimal one place to the right it should now look like (1.65*10^7)+(1.65*10^7)=5.91*10^7.
When you multiply or divide you multiply or divide the first factors. Then you add or subtract the exponents. For example(2*10^3)*(3*10^2) your going to multiply 2*3 and then your going to add 3+2=5 so your answer will be 6*10^5. Another example is where you do (9*10^8)/(3*10^-4), your going to divide the 9/3=3 and then your going to subtract 8-(-4)=12 and then your final answer will be 3*10^12
So for 0.00040230 there would only be five significant numbers because there are three nonzero numbers, a final zero, and a zero between two non-zero numbers. The rest of the zeros are placeholders.
A graph is a visual display of data. People use all kinds of graphs the most common are circle graphs, bar graphs, and line graphs. When interpreting a graph you must first identify the independent and dependent variables. Look at the ranges and consider what measurements were taken. Decide if the relationship is linear or nonlinear.
Tek: 2.H, 2.I
Law of Conservation of Mass
It was made by Antoine Lavoisier (1743-1704).
>The Glencoe Chemistry Matter And Cange Book