Properties and Physical and Chemical Changes of Matter

8/29/13 Scribe Post Author: Juliette O.

Class on 8/29/13    

8/28/13 Homework Check 

In the beginning of class, Ms. Friedmann checked in everyone's homework from Wednesday, 8/28/13. The homework due today was the WebAssigns on Chapter 1: 1.1 and 1.2, the notes on the ChemThink Particulate Nature of Matter Tutorial and quiz questions, and the two Particulate Nature of Matter green sheets in the composition notebook. 

After checking in the homework, Mrs. Friedmann addressed questions about the Internet activities (WebAssign and ChemThink), and then we went over the green Particulate Nature of Matter worksheets and the blue Paper Clip activity in our composition notebook. We then took a quiz on Section 1.1 in the book. We took notes on the second and third Questions for Today.

If you were absent today, you are responsible for showing Mrs. Friedmann the homework that was due today and checked in today. You are also responsible for taking the quiz in the Test Center.

Questions for Today:

How comfortable do you feel with telling the difference between:

--elements and compounds

--mixtures and pure substances

--atoms and molecules?

·      What is the difference between a property and a change?

·      How is physical different from chemical? 

Questions about Web Assign and ChemThink

First, some people reported to Ms. Friedmann that there were glitches in WebAssign or ChemThink. Her tips:

•  If there is a glitch, notify Ms. Friedmann with an email and, if possible, a screenshot of the problem.
• Don't get hung up on the glitch; try to complete the assignment, but if you have a problem make sure to talk to Ms. Friedmann and let her know about it.

Second, WebAssigns, no matter what number of points they were out of online or how many questions, are always out of 10 points.  Whatever percentage you got on the assignment is taken out of those 10 points.

Third, sometimes Mrs. Friedmann will assign a WebAssign on a topic that we have not learned yet, so the lesson the next day is review.

 Mrs. Friedmann also reminded us that we should always check the Chemistry Blog, Moodle page and Daily Homework Log each night!

Homework Check

 Paper Clip Activity

We went over the paper clip activity in class today. 

Examples:

1) Sample # 3: 3 Jb

This sample has 0 molecules because each atom of Jb is individual. The coefficient 3 shows that there are 3 individual atoms of Jb. If the formula looked like Jbsubscript 3, there would be 1 molecule, because the subscript 3 means there is a molecule made up of 3 atoms.

2) 2 Sm3 + JbCl2

The plus sign shows us that this is a mixture. 2Sm3 is a polyatomic element, because each atom is the same element and there are many atoms in the molecule. JbCl2 is a compound, because there is more than one element.

Notes to Consider:

• ·      If there is only 1 kind of element (such as 3Jb) in the sample, then it is an element.
• ·      The + sign implies that there is a mixture; no + implies a pure substance.
• ·      Pure substance: all the smallest individual pieces are the same
• ·      Homogenous Mix: Same throughout (blood)
• ·      Heterogenous Mix: Different throughout (fruit salad, medicine you shake)

Particulate Nature of Matter Worksheets

We went over the worksheets in class.  

Notes to Consider:

• ·      A compound is always a molecule, but a molecule is not always a compound.
• ·   Allotrope: each of two or more different physical forms in which an element can exist. (Element that exists as monatomic, diatomic and polyatomic)

• Ex: there are many different kinds (allotropes) of carbon-- bucky balls, carbon nanotubes, diamond, graphite in pencil. Nanotech uses carbon allotropes. 

·      When describing pictures of a sample of matter or a formula, ask yourself:

·      Atom or molecule?

·      Mixture or Pure Substance?

·      Element or Compound?

Quiz on Section 1.1

We had a short quiz on Section 1.1 in the textbook. If you were absent, you should make up the quiz in the Test Center.

Notes: 

Properties versus Changes 

Property: A substances potential to change. 

• The ability to:
• react with an acid
• melt at 50 degrees celsius ("melting point")

Change: A before and after. 

• The actual process of:
• reacting with an acid
• melting 

Physical Changes vs. Chemical Changes

Physical Change: The identity of the substance stays the same

Chemical Change: The identity of the substance changes.

To get to notes, go to GBS moodle. Click on Chemistry Honors 173  Friedmann, and go under Resources to Unit 1 Handouts. Under Unit 1 Handouts, there should be a link to 8/29 Notes on Chemical and Physical Changes. 

Thursday, 8/29 Homework

1) WebAssign 1.2 -- Measurement and Sig Figs.  Due Saturday night by 11:59 pm.  A friendly suggestion:  plan your weekend accordingly!  Since you have no other homework for now, I strongly suggest you work on this assignment tonight.  You do not need to finish WebAssigns all in one sitting; you can save your work and come back to it later.  If you choose to do this, however, do not forget about your Saturday night deadline as you enjoy Friday and Saturday!

2) We took a quiz on section 1.1 of the text today.  If you were absent, please make it up in the test center when you return.

The next scribe post author is Katie Coy.