Identify the element with the electron configuration [Rn] 7s^2 5f^14 6d^3.

To determine the element with the electron configuration [Rn] 7s^2 5f^14 6d^3, it's important to break down the configuration. The configuration begins with [Rn], which represents radon, a noble gas with 86 electrons. After radon, the next parts of the configuration indicate additional electrons in various orbitals.

The configuration includes 2 electrons in the 7s orbital, 14 electrons filling the 5f orbital (which corresponds to the actinides), and 3 electrons in the 6d orbital. The 5f block elements are actinides, and when counting the total number of electrons, which is 86 from radon plus 2 from the 7s, 14 from the 5f, and 3 from the 6d, you arrive at a total of 105 electrons.

Element 105 on the periodic table is dubnium (Db), making it the correct match for the given electron configuration. This can be verified by consulting the periodic table of elements, where dubnium is found within the transition metals, specifically in the 7th period with an emphasis on the d-block.

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