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Anonymous asked in Science & MathematicsChemistry · 1 decade ago

In each pair which ion is larger: Ca2+, Mg2+ Cl-, P3- Cu+, Cu2+ Please explain. Thanks!?

Update:

Compare EACH TWO ions, like between Ca2+ and Mg2+ which one is bigger...

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  • 1 decade ago
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    As a general rule Anions [negatively charged atoms (atoms with an extra e- in their outermost valence orbital)]are larger than their parent atoms and parent atoms are larger than Cations (atoms with one less e- in its outermost valence orbital which cause the ion to have a +1 charge). As general rules: the atomic radius (for atoms) increases as you move down and left across the periodic table, the ionic radius for cations increases as you move up and left, and the ionic radius for anions increases as you move up and right.

    To answer your question: (out of Ca2+ and Mg2+ )Mg2+ is larger because it they are cations and Mg is above Ca; (out of Cl- and P3-)Cl- is larger because they are anions and Cl is to the right of P; (out of Cu+ and Cu2+)CU+ is larger because the Cu+ is has a more negative charge than Cu2- in essence, the larger the negative charge, the larger the ionic / atom radius will be and the larger the radius, the larger the atom / ion.

    Hope that helps.

    Source(s): I'm an AP chem student. Sorry for the lengthy essay, but periodic properties are complex.
  • 1 decade ago

    Ca2+ vs. Mg2+ Ca2+ both are 2+ cations, Ca is lower on periodic table so should be larger

    Cl-1 vs. P3- P3-, both are anions in the same period (row) with the same number of electrons, then each have a noble gas electron config [Ar] P has fewer protons (Zeffective) than Cl.

    Cu+1 vs Cu+2 Cu+1 removing another electron only makes an atom smaller

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