Protons & Electrons in Ions

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Problem

Identify the number of protons and electrons in the Sc³⁺ ion.

Solution

Use the Periodic Table to find the atomic number of Sc (scandium). The atomic number is 21, which means that scandium has 21 protons. While a neutral atom for scandium would have the same number of electrons as protons, the ion is shown to have a +3 charge. This means it has 3 fewer electrons than the neutral atom or 21 - 3 = 18 electrons.

Answer

21 protons, 18 electrons

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