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If you know only the following information can you always determine what the element...

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looielol | Student, Grade 11 | (Level 1) eNoter

Posted October 13, 2010 at 7:32 AM via web

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If you know only the following information can you always determine what the element is? (Yes/No).

a. Number of protons (yes or no)

b. Number of neutrons (yes or no)

c. Number of electrons in a neutral atom (yes or no)

d. Number of electrons (yes or no)

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ndnordic | High School Teacher | (Level 2) Associate Educator

Posted October 13, 2010 at 7:56 AM (Answer #1)

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The key to this is first to understand that in a neutral atom, the number of positive protons and negative electrons is always equal. Secondly, the  number of protons is always the atomic number of the element and uniquely identifies the element.

because of the existance of isotopes for all elements, the number of neutrons will vary and cannot be used by itself to determine the identity of the element.

That being said, for a) the proton # identifies the element.

for b) neutrons do not identify the element

for c) since it is neutral the # of electrons = # of protons = atomic number = identity of the element.

for d) since it does not specify if the substance is neutral or not, the number of electrons cannot be used to identify the element. It could be a cation or anion vs. a neutral ion, and could have a charge of anywhere from +1 to +4 to -1 to -3.

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lizzie4eve | Student | eNotes Newbie

Posted January 5, 2012 at 12:13 AM (Answer #2)

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Yes on Number of protons!!!

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