chapter2_nddg


 * Chapter 2: Units and Measurements

Scientific Method-** is the logical approach to solving problems by observing and collecting data, formulating hypotheses, testing hypotheses, and formulating theories that are supported by data.


 * Qualitative-** descriptive observations of the reaction of the properties of the reactant(color, texture, etc.)


 * Quantitative-** numerical measurement or weighing of anything


 * System**- a specific portion of matter in a given region of space that has been selected for a study during an experiment or observation.

In an experiment the conditions that remain the same are called **constants** and what tested that changes is called a **variable**.
 * Hypothesis-** testable statement that surves as a basis for making predictions and for carrying out further experiments. (if-then statements work)

A **model** in science is more than a physical object; it is often an explanation of how phenomena occur and how data or events are related. Models can be visual, verbal, or mathematical. If a model explains many phenomena, it may become a theory.

A **theory** is a broad generalization that explains a body of facts or phenomena.


 * Stages in the scientific method**
 * **Observing**
 * -C**ollecting data

-Experimenting

-Measuring

-Communicating
 * Formulating a hypotheses**
 * -**Organizing and analyzing data

-Classifying

-Inferring

-Predictions

-Communicating

-Predicting
 * Testing**

-Experimenting

-Communicating

-Collecting data

-Measuring -Constructing models
 * Theorizing**

-Predicting

-Communicating

-Communicating
 * Publish Results**

A **quantity** is something that has magnitude, size, or amount. A quantity is not the same as a measurement. For example, the quantity represented by a teaspoon is volume. The teaspoon is a unit of measurement, while volume is a quantity.


 * //__Scientist all over the world agreed on a single measurement system called Le Systeme International d’Unites, SI. SI units are defined in terms of standards of measurement.__//**

Combinations of SI base units form **derived** **units**.
 * Weight** the measure of the gravitational pull on matter.


 * Volume** is the amount of space occupied by an o bject.


 * Density** is the ratio of mass to volume, or mass divided by volume.


 * Conversions Factor** is the ratio made up of two equal but different units that are used in dimensional analysis.


 * Dimensional Analysis** is a mathematical way to convert different units and get an answer. Often used in stoichiometry to convert grams to moles and then sometimes to another substance


 * Prefix Chart** ||
 * Tera ||  ||
 * T ||
 * 10^12 ||
 * 1000000000 ||
 * Giga ||  ||
 * G ||
 * 10^9 ||
 * 1000000000 ||
 * Mega ||  ||
 * M ||
 * 10^6 ||
 * 1000000 ||
 * kilo ||  ||
 * k ||
 * 10^3 ||
 * 1000 ||
 * Hecto ||  ||
 * h ||
 * 10^2 ||
 * 100 ||
 * Deka ||  ||
 * da ||
 * 10^1 ||
 * 10 ||
 * N/A ||
 * 10^0 ||
 * 1 ||
 * Deci ||  ||
 * d ||
 * 10^-1 ||
 * 1/10 ||
 * Centi ||  ||
 * c ||
 * 10^-2 ||
 * 1/100 ||
 * Milli ||  ||
 * m ||
 * 10^-3 ||
 * 1/1000 ||
 * Micro ||  ||
 * m ||
 * 10^-6 ||
 * 1/1000000 ||
 * Nano ||  ||
 * n ||
 * 10^-9 ||
 * 1/1000000000 ||
 * Pico ||
 * p ||
 * 10^-12 ||
 * 1/1000000000000 ||
 * Femto ||
 * f ||
 * 10^-15 ||
 * 1/1000000000000000 ||
 * Atto ||  ||
 * a ||
 * 10^-18 ||
 * 1/1000000000000000000 ||
 * Pico ||
 * p ||
 * 10^-12 ||
 * 1/1000000000000 ||
 * Femto ||
 * f ||
 * 10^-15 ||
 * 1/1000000000000000 ||
 * Atto ||  ||
 * a ||
 * 10^-18 ||
 * 1/1000000000000000000 ||
 * Atto ||  ||
 * a ||
 * 10^-18 ||
 * 1/1000000000000000000 ||
 * 1/1000000000000000000 ||


 * Accuracy vs Precision** Accuracy is producing the correct answer only once without confirmation and precision is producing that same answer multiple times to prove that it is not just coincidence to prove that it is accurate. It is more important to be precise than accurate.


 * Percent error** is found by subtracting true value from experimental value and dividing by the true value. Then multiply by 100. it is used to find how close you were to the accepted answer. For example if the experimental value is 42 and the true is 37 the percent error is 13.5%

Rounding sig figs- Rounding is all the same except for 5. it will always round to the even number. 16.5 à 16 and 17.5 à 18
 * Significant Figures** (sig figs) are measurements that consist of the digits known plus one that is estimated. The answer can only have as many sig figs as the measurement with the least sig figs in it. If one of the measurements in the equation only has 2 sig figs then the final answer can only have 2 sig figs.


 * Scientific Notation** is a form of notation in which the value is very large, and the scientists change it around to make it more managable. The first value in Scientific Notation is greater than 1 but less than 10. An example of Scientific notation is 3.47*10^14 or 3.47E14


 * Density** is the mass to volume ratio. D=m/v


 * Archimedes' principle** is used to calculate the volume of an irregularly shaped object. He discovered that the amount of water displaced is the same as the objects mass.