Thursday 9,16,2010

Today in the beginning of class Mr Paek made a couple of announcements about the upcoming week, here are the dates:

• chem think is due tomorrow-17/9
• web assign is due Monday-20/9
• Quiz on Monday-20/9

Quiz will be on molecules,atoms,compounds, the quiz will also have like 1 density problem and 1 measuring problem.

• lab test Tuesday-21/9
• test - sometime during the week.

Then Mr Paek explained to us the difference between physical and chemical change:

-physical change: do not affect chemical position.

some chemicals present.

same arrangement of atoms.

-chemical change: alter chemical composition

new chemicals formed

bonds broken and formed

rearrangement of atoms

after we did a chemical and physical changes sheet. we had 17 examples, where we had to decide weather the change is physical or chemical.

-some examples:

snow turning into water= physical change

hammering gold into a thin sheet=physical change

phosphorus burning=chemical change

We then did the physical or chemical stations lab: the lab was really easy we had to go through stations.

examples= in station 1 we had to watch melting candle wax, which was physical change. then burn candle wax and wick, which was a chemical change.

in station 4 we had to add water and food coloring, which was physical change. then melt ice in water which also was physical change.