Multiple Choice
What is the charge of the metal ion in the complex [Fe(NH_3)_2Br_4]^{2-}? (Omit the + sign in your answer.)
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2. Atoms & Elements
Ions
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If an unknown monatomic ion with a 3- charge has 10 electrons, what is the formula for that ion?
A
Ne^{3-}
B
N^{3-}
C
O^{3-}
D
F^{3-}
Verified step by step guidance1
Identify that the ion is monatomic, meaning it consists of a single atom with a charge of 3-. This means the ion has gained 3 extra electrons compared to its neutral atom.
Use the given number of electrons in the ion, which is 10, to find the number of protons (atomic number) in the neutral atom. Since the ion has a 3- charge, the neutral atom must have 3 fewer electrons: $\text{Number of protons} = 10 - 3 = 7$.
Recall that the atomic number corresponds to the number of protons and identifies the element. Look up the element with atomic number 7 on the periodic table, which is nitrogen (N).
Write the formula for the ion by combining the element symbol with the charge. Since the ion has a 3- charge, the formula is $\mathrm{N}^{3-}$.
Verify that the number of electrons in $\mathrm{N}^{3-}$ matches the given number (10 electrons) by adding the 3 extra electrons to the neutral nitrogen atom's 7 electrons.
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