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Why chlorine atom becomes Cl- , when it gains one electron?   

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pranitingale | Student, Grade 9 | Valedictorian

Posted March 7, 2012 at 11:30 PM via web

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Why chlorine atom becomes Cl- , when it gains one electron?

 

 

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bandmanjoe | Middle School Teacher | (Level 1) Senior Educator

Posted March 8, 2012 at 2:46 AM (Answer #1)

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Atoms in their natural state have a one to one ration between the positive charges of the protons and the negative charges of the electrons.  The only way to create an ion, which is a positively or negatively charged atom, is to either add an electron or lose an electron.  If you add an electron, as is the case with chlorine, you upset the balance between the positive and negative charges.  There are 18 electrons and 17 protons, so the chlorine atom has become a charged chlorine ion with a charge of negative one (-1).   To illustrate this, let us consider the formation of salt, sodium chloride, from a sodium atom and a chlorine atom.

Sodium has one electron in its outer energy level, it will willingly give this electron up to any takers.  When it does, the sodium atom becomes a sodium ion with a charge of positive one (+1).  Chlorine, as mentioned above, desperately wants an electron so it can fill its outer electron level.  When it takes on that extra electron, it becomes a chlorine ion, with a charge of negative one (-1).  The positive and the negative go together just like opposite ends of magnets, a north pole to a south pole, and create a very strong ionic bond between the sodium and the chlorine.

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mhamha23 | Student | eNoter

Posted March 7, 2012 at 11:36 PM (Answer #2)

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When an atom gains an electron, generally speaking, it becomes negatively charged. This is because the atom itself is neutral as there is an equal number of positively charged protons and negatively charged neutrons, each with a charge of plus or minus 1.

If the atom then gains an electron there will be one extra electron. In the case of chlorine, it will have 17 protons and 18 electrons, meaning that its charge will be -1.

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thecriminalmind | Student, Grade 10 | eNoter

Posted March 8, 2012 at 7:23 AM (Answer #3)

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Because Chlorine is gaining one electron which makes it's ratio of positive particles to negative particles unbalanced. There are more negative electrons now which makes neutral Cl into Cl- because now the atom has a negative charge.

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twinkysweet30 | Student, Grade 11 | Salutatorian

Posted March 11, 2012 at 1:13 AM (Answer #4)

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When an atom gains an electron, generally speaking, it becomes negatively charged.negative electrons makes neutral Cl into Cl- because now the atom has a negative charge.

If the atom then gains an electron there will be one extra electron. In the case of chlorine, it will have 17 protons and 18 electrons, meaning that its charge will be -1.

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