Friday, March 27, 2015

PROPERTIES OF MATTER

Matter is anything that occupies space and has mass. There are three states of matter:

  •  solid
  •  liquid
  • gas. 

Matter can be classified according to two properties:

  •  physical (properties observed without changing the composition of the substance)
  •  chemical (properties that describe the tendency of a substance to undergo chemical reactions that change its chemical composition)
Physical properties can be described as:

  • intensive or 
  • extensive. 
What is an intensive property?
Intensive properties are the same for all samples and do not depend on sample size. Examples: color, physical state, melting and boiling points, optical density. 

What is an extensive property?
Extensive properties depend on the amount of material. and include mass and volume. 
The ratio of two extensive properties, mass and volume, is an important intensive property called density.


What is a physical change?
A physical change involves the conversion of a substance from one state of matter to another, without changing its chemical composition. 

Most matter consists of mixtures of pure substances, which can be:

  •  homogeneous (uniform in composition) or 
  • heterogeneous (different regions possess different compositions and properties). 
What is a pure substance?
Pure substances can be either chemical compounds or elements. 

What is the difference between a compound and an element?
Compounds can be broken down into elements by chemical reactions, but elements cannot be separated into simpler substances by chemical means.   

Read more by clicking on this link.

Monday, March 23, 2015

JOKE FOR THE DAY! ENJOY!

One year, James decided to buy his mother-in-law a cemetery plot as a Christmas gift. The following year,  he didn't buy her a gift. When she asked him why, he replied, "Well, you still haven't used the gift I bought you last year!" 
Then a fight broke out.