C is for Chen-mistry

Ms. Chen, this is way too much work

MOVING ON..

2-4 

Chemical and Physical Changes

Chemical change: 

• changes that form a new kind of matter with another set of properties
• irreversible (eg- a boiled egg can not change back into a raw egg)

Decomposition: is a particular chemical change when one type of matter comes apart to form 2 or more kinds of matter

Physical Change:

• no new matter is produced
• are reversible(eg-when you freeze water, it'll become ice; when you melt the ice, it'll turn back to water)

More Fun Terms!

melting point: the temperature at which a solid melts or becomes a liquid

boiling point: the temperature at which a liquid changes into gas

2-5

Compounds and Elements

Electrolysis is the process that involves passing an electric current through a substance, causing it to decompose into new kinds of matter.

The example in the book shows that if the battery is left connected, chlorine gas and sodium metal will form in its(melted salt) place.

As you know, there's a difference in decomposition and distillation

 Hikari said, "Solutions  are separated into their component parts using a procedure called distillation." It is also a PHYSICAL change
Whereas decomposition involves a single pure substance that is somehow changed into a new substance with different properties. It is a CHEMICAL change.


Compounds are a final product of a combination of simpler substances.For example- hydrogen and oxygen forms water!sodium and chlorine forms salt!and so forth. Pure substances that cannot be decomposed are called elements.

2-6
Compounds Have a Definite Composition
Leading on from 2-5, elements are a kind of matter that can't be decomposed. An important diff between the mixtures of elements and the compounds of elements is that mixtures are any combination of elements that are desired, whereas compounds of elements have a fixed composition. This fact is also called law of definite composition, it's usually described in volume..but can also be used in terms of mass.
The law of multiple proportions describes two or more compounds with diff proportions of the same elements




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