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describe how the size changes when an atom forms a cation and when an atom forms an anion

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r4rob92 | (Level 1) Valedictorian

Posted October 17, 2012 at 9:29 AM via web

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describe how the size changes when an atom forms a cation and when an atom forms an anion

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jerichorayel | College Teacher | (Level 1) Senior Educator

Posted October 17, 2012 at 10:07 AM (Answer #1)

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Hello!

When an atom ionizes, either they accept or transfer electrons, their radius changes. 

In the formation of cation, the radius of the cation is generally smaller than its atom. For example:

The radius of Na+ is smaller than Na atom

 

In the formation of anion, the radius of the anion is larger than its atom. For example:

The radius of Cl- is bigger than Cl atom

 

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This happens because when an atom accepts or gives up an electron to form an ion, it generally assumes a noble gas configuration.

For Na, when it loses an electron, its outer shell will be removed thus having a smaller ionic radius. It will have a similar configuration to that of Neon.

In the case of Cl, as it receives another electron, its configuration is like that of Argon, thus increasing its radius.

 

 

hope this helps :)

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luiji | Student, Grade 11 | (Level 1) Salutatorian

Posted October 17, 2012 at 1:19 PM (Answer #3)

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When an atom becomes a cation, it loses electrons, which means it loses an outer shell. This means it becomes smaller.

 

When an atom becomes an anion, it gains electrons, which means it gains an outer shell. This means it becomes bigger.

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angelsallu | Student, Grade 9 | (Level 1) Honors

Posted October 17, 2012 at 2:58 PM (Answer #4)

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HI

The size of the atom becomes smaller when its a cation. It is smaller because it is positively charged meaning it has lost 1 or more electrons making it smaller.

The size of the atom becomes larger with the anion. It is larger because it is negatively charged meaning it has gained 1 or more electrons making it bigger in size.

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