Assignment 2

#1. Element of the Week - Iron

Periodic Table Information: Atomic Number: 26; Symbol: Fe, Atomic Weight: 55.847 Electron Configuration: [Ar]4s23d6

Properties: The melting point of iron is 1535°C, boiling point is 2750°C. Pure iron is chemically reactive and corrodes rapidly, especially in moist air or at elevated temperatures.

Uses: Iron is vital to plant and animal life. In humans, it appears in the hemoglobin molecule. Iron metal is usually alloyed with other metals and carbon for commercial uses. Iron is the least expensive, most abundant, and most used of all metals.

Sources: Iron is a relatively abundant element in the universe. The sun and many types of stars contain iron in quantity. Iron is found native in a class of meteorites called siderites and it is a minor constituent of the other two classes of meteorites. The Earth's core is thought to be composed mainly of iron. Iron is the fourth most abundant element in the Earth's crust. The most common iron ore is hematite (Fe2O3), from which iron metal is obtained by reduction with carbon. Iron is also found in minerals such as taconite and magnetite, which is commonly seen as black sands along beaches and stream banks.

#2. Discussion about Ozone

In discussing Ozone with my friends and family I discovered that most everyone was at least up to speed on the notion that pollution contributes to ozone depletion.

No one was aware that new evidence shows that pollution is not the major cause of ozone depletion, but rather climate change. I explained that as of April 2005, ozone was at its lowest levels in 40 years, despite the reductions in CFCs due to the Montréal protocol. I explained that changes in the atmosphere due to climate change are allowing pollutants to destroy the ozone. This was a sobering realization for everyone with whom I spoke. Most everyone has been more focused on climate change anyway. For the most part they have not been thinking much about ozone levels, assuming it is improving. No one had any idea that it was getting worse. And, it was startling for all to realize that ozone depletion is directly affected by climate change. This reinforced everyone's desire to see a new administration in office. We also talked about what we as individuals could all be doing to further reduce our contributions to pollution and climate change.

#3. Review of link on Atomic Structures, Bonding and Compounds.

This was a really cool site. I was so happy to see something simple and straightforward. The graphics were really helpful and the definitions were mostly clear, but I’m confused about the difference between a molecule and a compound. I think this should be easy to understand, but I don't get it. Both a molecule and a compound can be composed of atoms of different elements that are bound together. What am I missing? The definitions from this site are as follows:

ELEMENT

a. consists of only one kind of atom
b. cannot be broken down into a simpler type of matter by either physical or chemical means, and
c. can exist as either atoms (e.g. argon) or molecules (e.g., nitrogen).

MOLECULE consists of two or more atoms of the same element, or different elements, that are chemically bound together.

COMPOUNDS
a. consists of atoms of two or more different elements bound together,
can be broken down into a simpler type of matter (elements) by chemical means (but not by physical means),
b. has properties that are different from its component elements, and
c. always contains the same ratio of its component atoms.

MIXTURES

a. consists of two or more different elements and/or compounds physically intermingled,
b. can be separated into its components by physical means, and
c. often retains many of the properties of its components.