Chemistry is the science that deals with the structure and composition of matter and the changes in the compositions of these materials. All the different branches of science, such as chemistry, biology, and physics, are based on observation and the Scientific Method.

The Scientific Method

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

Steps in the Scientific Method include:

• Purpose

First, state the problem. What are you looking for or trying to find in the experimentation? Ask a question that can be answered through the experimentation. For example, if the experiment deals with plant growth, a question would be, “Does nitrogen fertilizer really help plants grow higher and greener?” and the purpose would be to gain knowledge so that you may start the process at home, or that you are simply curious and want to find out.

• Background Information

Research the topic in which the experimentation is going to take place so that you can have a general idea and make the predictions and inferences. It is important to research the topic so that you have prior knowledge to analyze the data with after experimentation.

• Form a hypothesis

The hypothesis is a testable statement that may include a prediction. It is usually in the form of an if-then statement, but it does not have to have the words “if” or “then.” It should have a possible explanation to a phenomenon. The hypothesis should not be confused with a theory.

• Materials and Procedures

List the materials needed and have them ready for use. Conduct a procedure that would guide through the experimentation. It should be a systematic process to complete the experiment with ease and precision.

• Test the hypothesis

This is where the main experimentation comes in. In this step, you are observing different variables and testing the hypothesis. Making observations is important in the experimentations. Observations may include drawing pictures, taking notes, or simply describing what is going on in the experiment. The independent variable in the experiment is the variable that you control. For example, if an experiment deals with plant growth. The amount of time of sunlight given to the plant would be the independent variable because you can control the amount of time of sunlight to give the plant. The dependent variable is the variable that is dependent upon the independent variable. The dependent variable is the change that is caused by the independent variable. For example, the growth of the plant under the sun is the dependent variable because the plant changes its height due to the amount of time in the sunlight. The control variable is anything in the experiment that has not been changed. There could be multiples of dependent variables, but there is only one independent variable in the experiment.

• Recording and Analyzing the Data

Record the data from the observations made, by forming a data table and graph. Make sure that other people can understand the information from the experiment. Take note on what is quantitative and qualitative. Quantitative deals with numbers, hence the root, quantity. For instance, there were two eyes on the frog, or there were two legs and two arms on a frog. Qualitative deals with the quality of data from the experiment. For example, the frog was green and had brown spots on its back, or the frog’s heart was small and pink. Analyze the data by discussing what the data illustrated. If any question were provided, answer them with detail. If not, then create your own questions by going in depth and include information from the background research because this will help you test your knowledge about the topic. Analyze the graph from the data. Is there enough information to know whether the hypothesis is correct? Is the data correct and accurate? Are there any patterns present? These are key questions to help analyze the data from the experimentation.

• Conclusion

The conclusion is the summary of the experiment and states whether the hypothesis was proved or disproved. State whether the hypothesis was correct in the experiment. If it was, explain how the hypothesis was correct by summarizing what has happening in the experiment, using details and support from observations and data. State what you have learned in the experiment and how you can have done differently in the future. If the hypothesis was disproved in the experimentation, state it, and give the results from the data. State what you could have done differently so that you can improve the experiment in the future. Give possible reason why the experiment did not support the hypothesis. State unavoidable errors and other errors that could have occurred in the experiment, because when recording findings, this information may influence the result.

Measurements in Chemistry

Measurements describe quantities, which is a property that can be measured by a number and a unit that names the standard use.

For example: 10 and 25 are numbers

10cm and 25kg are quantities

A quantity is not the same as a measurement because the quantity that is represented by a liter is volume. A liter is a unit of measurement, while volume is quantity. Quantities require units and as in math, only like quantities can be added or subtracted.

For example: Add 2 hours and 27 minutes. The sum is not 27 hours or 27 minutes, so the units must be changed so they are the same: 120 minutes (2 × 60 minutes) + 25 minutes = 145 minutes. In science, scientists all over the world use the SI system. It is abbreviated from the French term, Le Système International d’Unités, which stands for The International System of Unites. This system is very popular because it uses the same numerical base as the decimal number system, in which every unit in the system is ten times the size of the next smaller units. In other words, it is the modern form of the metric system.

Scientific Notation

Many calculations in science involve very large numbers or very small numbers. These numbers involve large strings of zeros. To facilitate these calculations, a number between 1 and 10 is multiplied by some power of 10. This form is called the scientific notation and the parts include:

1.5 × 103 where 1.5 is the decimal part and 103 is the exponential part.

A power is a product obtained by multiplying together two or more equal factors, for example: x4. An exponent, also called an index, is the name given to the number that indicates the number of factors that have been multiplied together to produce the power.

For example: The exponent 4 indicates a4 = a × a × a × a.

Contrast the scientific notation with expanded notation, which is the form most people are used to using, where the numbers are written in their expanded form.

For example: 1.5 × 103 = scientific notation

1500 = expanded notation

The laws that govern the use of exponents (or indices) that are used frequently are:

Law of Multiplication: xm × xn = xm+n

For example: 103 × 104 = 107

Law of Division: xm ÷ xn = xm−n

For example: 107 ÷ 102 = 105

Law of Powers: (xm)n = xm×n

For example: (105)3 = 1015

Negative exponents are defined by the formula: x-m = 1/xm For example: 10-1= 1/10 = 0.1

Exponential notation, another name of scientific notation, also expresses any number as a product of a number between 1 and 10 and an integral power of 10.

For example: 275 = 2.75 × 100 = 2.75 × 102

0.00043 = 4.3 × 1/1000 = 4.3 × 10-4

The rule for converting decimal fractions to exponential notation is that it always have negative powers of 10 and the absolute value of the exponent is always one greater than the number of zeros immediately after the decimal point.