Thursday, October 14, 2004

Lesson 17

Isotopes, Periodic Table

Atoms of the same element can have different numbers of neutrons; the different possible versions of each element are called isotopes. For example, the most common isotope of hydrogen has no neutrons at all; there's also a hydrogen isotope called deuterium, with one neutron, and another, tritium, with two neutrons.
You can find more about isotopes on the following website:

http://www.colorado.edu/physics/2000/isotopes/


Periodic Table - Division of Metals and Nonmetals

Metals, Nonmetals, & Metalloids
- Ionic Compounds
Most periodic tables contain a stairstep line which allows you to identify which elements are metals, nonmetals, and metalloids. Following are descriptions of each of the three types of materials.


Metals


Most elements are metals. 88 elements to the left of the stairstep line are metals or metal like elements.


Physical Properties of Metals:
Luster (shininess)
Good conductors of heat and electricity
High density (heavy for their size)
High melting point
Ductile (most metals can be drawn out into thin wires)
Malleable (most metals can be hammered into thin sheets)
Chemical Properties of Metals:
Easily lose electrons
Corrode easily. Corrosion is a gradual wearing away. (Example: silver tarnishing and iron rusting)


Nonmetals
Nonmetals are found to the right of the stairstep line. Their characteristics are opposite those of metals.


Physical Properties of Nonmetals:
No luster (dull appearance)
Poor conductor of heat and electricity
Brittle (breaks easily)
Not ductile
Not malleable
Low density
Low melting point

Chemical Properties of Nonmetals:

Tend to gain electrons

IONIC COMPOUNDS:
Since metals tend to lose electrons and nonmetals tend to gain electrons, metals and nonmetals like to form compounds with each other. These compounds are called ionic compounds.

When two or more nonmetals bond with each other, they form a covalent compound.


Metalloids
Elements on both sides of the zigzag line have properties of both metals and nonmetals. These elements are called metalloids.


Physical Properties of Metalloids:
Solids
Can be shiny or dull
Ductile
Malleable
Conduct heat and electricity better than nonmetals but not as well as metals

Find out more about metals, nonmetals and ionic compounds at:
http://web.buddyproject.org/web017/web017/metals.html

Homework:

pg. 97 #1-3, Text
pg. 28,29,34 Course Pack
Gold Dust Kid Story

4 Comments:

At October 14, 2004 at 5:44 PM, Blogger Wu said...

Hey Mr. D., for the Gold Dust Kid assignment. Do all the words have to make sense with the story or can the word be used kind of like Americium instead of saying America?

Also, does the story have to be fictional or non-fictional??

Thanks, Wu (James)

 
At October 14, 2004 at 7:33 PM, Blogger andrewl200 said...

Hey, Dr.D,
ok i did some more research and i found this site
http://www.healthy.net/scr/article.asp?ID=2066

"There is no specific RDA for sulfur other than the amino acids of which they are part are needed to meet protein requirements. Our needs are usually easily met through diet. About 850 mg. are thought to be needed for basic turnover of sulfur in the body. There is not much information available on sulfur content of foods, nor are there supplements specifically for sulfur. I have found that it is not really a nutritional concern."

For that 850mg for a day? a month or for a year?

James,
I think the story has to be fictional.. haha

Thanks,
Andrew Lei

 
At October 14, 2004 at 8:07 PM, Blogger N. Doctorow said...

Andrew,

Let's talk about a new chemical. James, get real man!!! It can be fictional or not. As for whether or not it has to make sense - of course it has to make sense.

Mr. D.

 
At October 15, 2004 at 8:32 PM, Blogger andrewl200 said...

Thanks Mr.D! :D

 

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