Multiple Choice
What are the two ions that water molecules can dissociate into?
2. Atoms & Elements
Ions
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Which of the following ions have different numbers of electrons?
A
O2- and S2-
B
Ca2+ and Mg2+
C
Fe2+ and Fe3+
D
Na+ and Cl-
Verified step by step guidance1
Identify the atomic number of each element to determine the number of protons, which equals the number of electrons in a neutral atom.
For O2-: Oxygen has an atomic number of 8, so a neutral oxygen atom has 8 electrons. The O2- ion has gained 2 additional electrons, resulting in 10 electrons.
For S2-: Sulfur has an atomic number of 16, so a neutral sulfur atom has 16 electrons. The S2- ion has gained 2 additional electrons, resulting in 18 electrons.
For Ca2+: Calcium has an atomic number of 20, so a neutral calcium atom has 20 electrons. The Ca2+ ion has lost 2 electrons, resulting in 18 electrons.
For Mg2+: Magnesium has an atomic number of 12, so a neutral magnesium atom has 12 electrons. The Mg2+ ion has lost 2 electrons, resulting in 10 electrons.
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