Friday, November 6th, 2009

Today the class started with awful news: The test is on November 20^th!

So if anyone else was planning to go to the New Moon´s premier you need to come early to school, even if you´re sleepless.

So...

Today´s theme was Chemical formulas and equations

An equation can tell you the elements that you have, the cuantity and, in some cases, the state or compatibility.

A chemical formula is a concize way of expresiing information about the atom that constitute a particular chemical compound.

Every compund that exists has an specific formula.

There are some elements that don´t come alone. They come in pairs:

H2

O2

N2

F2

CL2

BR2

I2

There was another theme today: Types of chemical reactions.

All chemical reactions involve a change in substances and a change in energy. Neither matter or energy is created or destroyed in a chemical reaction, only changed.

There are four types:

SYNTHESIS REACTION
In a synthesis reaction two or more simple substances combine to form a more complex substance.

DECOMPOSITION REACTION
In a decomposition reaction a more complex substance breaks down into simpler parts. Synthesis and decomposition reactions are opposites.

SINGLE REPLACEMENT REACTION
In a single replacement reaction a single uncombined element replaces another in a compound.

DOUBLE REPLACEMENT REACTION
In a double replacement reaction parts of two compounds switch places to form two new compounds.

Erin Alice Gil

The homework was:

Find 3 examples of each type of reaction.