Grade 10 - Chemistry - LO.1 - Science methods, laws, theories

We have in LO.1 Chemistry G10

First: the Concepts

Science.

Scientific methods.

Scientific law.

Scientific theory.

Relations between variables.

Uncertainty.

SI units.

Instrumentation (precision, accuracy, significant figures).

Types of variables.

Density.

Specific gravity.

Second: the References

Zumdahl: ch.1 sec.3,4,5

Third: the Videos links

Fourth: Skills

Use laboratory equipment to get measurement data . 

Represent data on data tables and graphs correctly 

Differentiate scientific from non-scientific reasoning . 

Develop a chart of main processes in scientific thinking . 

Demonstrate proper use of quantitative instrumentation . 

Conduct and analyze series of measurements . 

Evaluate scientific reports as to their use of quantitative instruments reporting and analysis of findings. 

Determine number of significant figures .

Measure and calculate densities of materials . 

Compare densities of solids, regular and irregular and liquid materials by their behavior and gross observation

Fifth: the materials as PPT., DOCX., and PDF

In the Drive from this link

Few Notes:

-Science: The systematic building which organizes knowledge in the form of facts, principles, concepts, scientific theories and an organized way of search.

Each branch of science is concerned with the study of certain phenomena.

-Chemistry: The science that studies the structure and properties of matter , changes that occur to it, reaction of substances with each other and the suitable conditions for it.

Chemistry had used in all fields of life (Medicine, pharmacy, glass industry, clothes dyeing… etc. )

The scientific method is the process by which scientists, collectively and construct an accurate that is, reliable, consistent representation of the world.

Recognizing both our perceptions and our interpretations of natural phenomena 

The scientific method steps:

1)Observation and description of a phenomenon or group of phenomena.

2)Formulation of a hypothesis to explain the phenomena

3)Use of the hypothesis to predict the existence of other phenomena, or to predict quantitatively the results of new observations.

4)Performance of experimental tests of the predictions by several independent experimenters and properly performed experiments.

A scientific law is a statement that describes an observable occurrence in nature that appears to always be true. 

In science, sometimes a law is called a 'principle.' The law or principle may describe the occurrence and predict it as well. However, a law does not make explanations about the natural occurrence.

Example:

-Newton's Law of Gravitational Force is written as g = GM / r2. This law describes gravitational force. 

-Laws are generally considered to be without exception, though some laws have been modified over time after further testing found discrepancies. 

-It is used in science, a theory is an explanation or model based on observation, experimentation, and reasoning, especially one that has been tested and confirmed as a general principle helping to explain and predict natural phenomena.

-Any scientific theory must be based on a careful and rational examination of the facts. A clear distinction needs to be made between facts (things which can be observed and/or measured) and theories(explanations which correlate and interpret the facts).

-A fact is something that is supported by unmistakable evidence. 

Relationship between variables

-It is very important to understand relationship between variables to draw the right conclusion. The relationship between variables determines how the right conclusions are reached. 

-There are several different kinds of relationships between variables. 

-Suppose you measure a volume of a gas in a cylinder and measure its pressure. Now you start compressing the gas by pushing a piston all while maintaining the gas at the room temperature. The volume of gas decreases while the pressure increases. You note down different values on a graph paper.

-If you take enough measurements, you can see a shape of a graph. 

-This is because gases follow Boyle's law that says when temperature is constant, PV = constant. Here, by taking data you are relating the pressure of the gas with its volume. Similarly, many relationships are linear in nature.

Accuracy and Precision

-Accuracy refers to the closeness of a measured value to a standard or known value. 

For example, if in lab you obtain a weight measurement of 3.2 kg for a given substance, but the actual or known weight is 10 kg, then your measurement is not accurate. In this case, your measurement is not close to the known value.

-Precision refers to the closeness of two or more measurements to each other. Using the example above, if you weigh a given substance five times, and get 3.2 kg each time, then your measurement is very precise. Precision is independent of accuracy. You can be very precise but inaccurate, as described above. You can also be accurate but imprecise.

For example, if on average, your measurements for a given substance are close to the known value, but the measurements are far from each other, then you have accuracy without precision. for understanding accuracy and precision imagine a basketball player shooting baskets. If the player shoots with accuracy, his aim will always take the ball close to or into the basket. If the player shoots with precision, his aim will always take the ball to the same location which may or may not be close to the basket. A good player will be both accurate and precise by shooting the ball the same way each time and each time making it in the basket. 

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