Help with science homework!!?

[Sarah=]]

Describe the parts of an atom, include their charge and unit used to measure each. What's the difference between the atomic number and the atomic mass. What's an isotope?

What's the difference between exothermic and endothermic reactions? What are the signs that a chemical reaction has taken place?

What is the difference between biotic and abiotic things? What are the levels of biological in an ecosystem? What does tropical level refer to?

What are symbotic relationships and describe and give examples of three basic ones?

Describe the nitrogen cycle.

Describe the carbon cycle.

[spaklesonia]

1.Atom is smallest particle of elemenet and compound which can take part in chemical reaction.
2.they are neutrally charged.
3.Atomic no are those in which no of proton is equal to no of electron.
4.Isotopes are those in which atomic no are same and mass no are different. like carbon.
EXOTHERMIC:- those reaction in which heat and light is evolved and reaction takes place outside.
ENDOTHERMIC:-those reaction in which reaction occurs inside.

ask me

all are ninth level question

[~*Ashley Star*~]

http://www.chem4kids.com/files/atom_structure.html

http://www.hazelwood.k12.mo.us/~grichert/atom/Periodic%20Law%20of%20the%20Elements/sld002.htm

http://library.thinkquest.org/05aug/01087/partsofatom2.html
^^parts of an atom
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http://chemistry.about.com/cs/generalchemistry/a/aa051903a.htm
http://www.emsb.qc.ca/laurenhill/science/exo.html

http://en.wikipedia.org/wiki/Endothermic
http://en.wikipedia.org/wiki/Exothermic

http://antoine.frostburg.edu/chem/senese/101/thermo/faq/exothermic-endothermic-examples.shtml
^^Endo and Exothermic
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i'll give you that start the rest u can look up on google :-)
Encarta (MSN), Wikipedia are great sources to use as well