Lab Experiment: Physical and Chemical Change

Today in chemistry we did a lab experiment on physical and chemical changes.

Physical changes:
-any change not involving a change in the substance's chemical identity
-occur when objects undergo a change that does not change their chemical nature
-involves a change in physical properties (i.e texture, shape, size, color, volume, mass, weight,
and density)
-REVERSIBLE
-an example of a physical change:
                                          formation of ice.
 

Resource: www.flickr.com

Chemical changes:

- bonds are broken and new bonds are formed between different atoms.

                            　　　　　　　　　　　↑

This breaking and forming of bonds takes place when particles of the original materials collide with one another

-when chemical change occur, the atoms are rearranged and the reaction is accompanied by an energy change as new products are generated.

-IRREVERSIBLE

-an example of chemical change:

                                        burning wood.

                                                        Resource: Yahoo! Image.

Leif Tung

Unit Conversion prepartion

              Schedule for the day :)

 


1. Start off correcting our homework on overhead.

2.Had  a practice quiz on unit conversion. 

3. Ms. Chen gave us precious time to study for the rest of the class.
 








How to prepared for an A+
      
       -Warm up by watching this video on Unit Conversion
       -Go over corrections on previous homework
       -Memorize the SI Prefixes table
       -Finish the last home on Unit Conversion
       -Try more practice quiz questions on this website              

Do last homework on Unit Conversion





Memorize this table

 
 Watch fun video on Unite Conversion




More Practice Quizes

                                                                     



Matter

Today, we had learnt about matter.

What is matter?

Matter is a general term for all physical objects are made and takes up space, in other words everything has volume.

Matter is divided into 2 separated parts. One is Pure Substances and Mixtures.

Now, let's talk about PURE SUBSTANCES first.

Pure substances have only one set of properties. They are generally divided into Element and Compound.

• 
  
  
  The Element is the simplest form which CANNOT be decomposed such as gold(Au); it is made of atoms. Atoms have 3 different properties such as metal, non-metal and metalloid.
• 
  
  
  The Compound is consist of two or more different chemical elements. For example, the formula for trifluoroacetic acid is written as C₂HF₃O₂. Then, the smallest particle is a molecule that is either ionic or covalent.
  
  
  • 
    
    
    An ion has a total number of elements that is not equal to the total number of protons, giving it a either positive or negative electrical charge. For example, Aluminum(Al^+3) and Carbonate(CO₃^-2).
  • 
    
    
    A covalent bond is a form of chemical bonding that is characterized by the sharing of pairs of electrons between atoms, and other covalent bonds.

Next up, MIXTURES!

Mixtures are more than one set of property and substance and they are physically combined by means of Homogeneity and Heterogeneity.

Homogeneity

is uniform in composition or character and appears to have only one component.
Heterogeneity
is not uniform and visibly consisting of different components. Ex. water+oil

Now, do you have a idea of physical change?

• A physical change does not involve any chemical change which means no new substance is formed. An example such as a kid broke a glass bottle accidentally

Bonds are broken and new bonds are formed in a chemical change. Some reactions may also cause certain chemicals undergo a change in state. An example of chemical change: combustion of methane to produce carbon dioxide and water.


(1)



A few more properties of matter:

1. Solid-is characterized by structural rigidity and resistance to change in shape easily and experiences small changes in volume when heated. (1)                                                                                       
2. Liquid-able to flow and take the shape of a container.(2)
3. Gases-are widely separated from one another and take the shape of the container.



(2)

(3)



Kevin Wang

scientific notation

Resource: Youtube.  Leif Tung

Chemistry 11: Scientific Notation, even more Uniting Rates.

Today in chemistry class we've learned about scientific notations and more uniting rates.

So, what is scientific notation?  Does it benefit us?  How?
Notice when you're solving math problems such as 125+521, you probably won't need to use scientific notation, you don't even need to use cauculator I believe.  But, since you're in a science class, you probably will meet such problems that encouters a huge quantities of ZERO.  In that kind of situation, scientific notation makes it easier for us to solve this kind of problems!  Scientific notation makes it simple to express very large and very small numbers using powers of 10 and to perform cauculations with these numbers.  Thus, scientific notation has helped advanced knowledge and has led to practical uses of this knowledge through technical development or in science.

Here is an example:
Ex. Express 25100000000 into scientific notation
       As you can see the number has quite a lot of ZEROs.  But we can use scientific notation to get rid of those ZEROs.
       1.locate the decimal points.  　25100000000.← 。
       2.and move the decimal points either left or right to make the number > 1 but <10.
                                                                       ←　　→                   = 2.5100000000
       3.count the number of places the decimal has moved.       2.5100000000   x   10
                                                                                                           10987654321 
       4.then place a x 10 beside the number, and whatever the number of places the decimal points was moved is the same as exponent.                                  ↑ 10 decimal places was moved
                                                                               2.5100000000 x 10^10
       5.See?!  After this procedure we've made 25100000000 a lot more easier to read!


Even more uniting rates.
     As we've learned before, 1km = 1000 m,   1m = 100cm.  But what if you receive such questions like 1m^2 =  ______ cm^2 ,  or  1m^3 = ______ cm^3 ?  Challenging, eh?
Let's take a look at this question: Convert 1m^2 to cm^2
                          we all know 1m = 100cm, now think about it, 10^2 = _____?  Yes, it's 10 x 10, therefore, it's the same meaning to cm^2, so what is 100 x 100?  It's 10000, so the answer to that question is 1m^2 = 10000 cm^2.  And now we can use the same idea to solve any kind of question like this.  
     For example:
                  Convert 8.1 m^3 to km^3.               1 km = 1000 m  → 10^3 m
                                                                             1 km^3 = 10^3 x 3 = 10^9 m^3   
                                      8.1 m^3  x  1 km^3      =   8.1 x 10^-9 km^3
                                                         10^9 m^3
                                                              ↑
                                                            flip it

                                                                                                                                  Leif Tung