Basic Chemistry Stuff

[kingwinner]

I am taking an Earth Science course now and currently reviewing some basic chemistry knowledge needed for further study on earh mineral and rocks. But I haven't touched chemistry for almost 2 years that I start to forget things, can someone help and clarify some basic chemistry stuff? I would appreciate!

1) Are the terms "element" and "atom" interchangeable? If not, why not?

2) Do the terms "substance" and "matter" mean exactly the same thing?

3) "Two of the eight common elements in the earth's crust are oxygen (O) and silicon (Si)"


Why is oxygen expressed as O, instead of O2, in both the quote and diagram? Does that mean single O atom exist naturally in the crust?

4) Compound: a substance that results when the atoms of two or more elements are chemically combined
This is the definition of a "compound" from my text book and it's the same as all sources in the internet. According to the definition of a compound, O2 and N2 are not compounds, than what are they? elements?

[Jay-qu]

Originally Posted by kingwinner

1) Are the terms "element" and "atom" interchangeable? If not, why not?

2) Do the terms "substance" and "matter" mean exactly the same thing?

3) "Two of the eight common elements in the earth's crust are oxygen (O) and silicon (Si)"

Why is oxygen expressed as O, instead of O2, in both the quote and diagram? Does that mean single O atom exist naturally in the crust?

4) Compound: a substance that results when the atoms of two or more elements are chemically combined
This is the definition of a "compound" from my text book and it's the same as all sources in the internet. According to the definition of a compound, O2 and N2 are not compounds, than what are they? elements?

1. element is the generic name for a type of atom - while an atom is the smallest unit of elements

2. Everything is made up of matter, matter is again a generic term - a substance is normally what you would call a sample of matter

3. sort of but not really, O atoms exsist in compounds in the crust - either in corroded metals (rust) or other covalent molecules such as your nitrates

4. They are elemental oxygen and elemental nitrogen - since they both dont normally exsist as just O and N they form molecules with themselves.

hehe 404 post count not found

[HydrogenBond]

The oxygen on the crust and surface exist mostly as oxides (M-O) of minerials. Then within water (H2O) and finally within atmospheric oxygen (O2). The high precentage of oxygen on the surface and atmosphere indicates a high percentage of oxygen within the mantle. Oxygen may be the most common element on/in the earth.

[Jay-qu]

Originally Posted by HydrogenBond

. Oxygen may be the most common element on/in the earth.

..and in the atmosphere its nitogen

[kingwinner]

Originally Posted by Jay-qu

4. They are elemental oxygen and elemental nitrogen - since they both dont normally exsist as just O and N they form molecules with themselves.

hehe 404 post count not found

4) A compound is a substance that results when the atoms of two or more elements are chemically combined
A molecule is the smallest unit of a compound that still retains its properties.

If the above 2 definitions are both true, than O2, H2, N2 are all not (diatmoic) molecules, since they do not meet the requirement that "two or more elements", each of O2, H2, N2 has only one element chemically combined?! But why are they always referred to as diatmoic molecules?