How many atoms of each element are in the chemical formula Ca(OH)2?

1 calcium, 1 oxygen, and 1 hydrogen
1 calcium, 2 oxygen, and 2 hydrogen
2 calcium, 1 oxygen, and 2 hydrogen
2 calcium, 2 oxygen, and 2 hydrogen

1 answer

The chemical formula Ca(OH)₂ represents calcium hydroxide. To determine the number of atoms of each element in this formula:

  • Ca indicates there is 1 calcium atom.
  • The (OH) indicates there is one hydroxide ion, which contains both oxygen and hydrogen. Since there is a subscript of 2 outside the parentheses, it means there are 2 hydroxide ions.
    • Therefore, from the hydroxide ions, there are 2 oxygen atoms (1 from each OH) and 2 hydrogen atoms (1 from each OH).

Putting it all together, Ca(OH)₂ consists of:

  • 1 calcium (Ca)
  • 2 oxygen (O)
  • 2 hydrogen (H)

Thus, the correct answer is: 1 calcium, 2 oxygen, and 2 hydrogen.