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Reviewed CSCA Chemistry question · Easy

Which element has the electron configuration 1s2 2s2 2p6 3s2 3p4?

  1. Oxygen (O)
  2. Sulfur (S)
  3. Selenium (Se)
  4. Chlorine (Cl)
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Correct answer

B. Sulfur (S)

Principle or equation

The electron configuration determines the atomic number; sum the superscripts: 2+2+6+2+4 = 16, which is sulfur.

Why this answer is correct

The configuration corresponds to 16 electrons, so atomic number 16, which is sulfur. Oxygen has 8, selenium 34, chlorine 17.

Example

For atomic number 12, configuration is 1s2 2s2 2p6 3s2.

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