An unknown element, X, reacts with rubidium to form the compound R b 2 X. In other compounds this element also can accommodate up to 12 electrons rather than the usual octet. What element could X be?

Question

Jasiah Travis

Chemistry

11 April, 15:15

An unknown element, X, reacts with rubidium to form the compound R b 2 X. In other compounds this element also can accommodate up to 12 electrons rather than the usual octet. What element could X be?

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Answers (1)

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Elle Munoz · Answer 1

Answer : The Correct answer is Tellurium (Te)

In the compound Rb₂X, Rb is Rubidium which belongs from s block and group 1. Also its electronic configuration is [Kr] 5s¹, which suggest that oxidation state of Rb is + 1. Since there are two Rb atoms present so total positive charge is + 2.

The compound is neutral means it has zero total charge so total negative charge is - 2. Also the there is one atom of X, so oxidation state of X must be - 2. Element with - 2 oxidation state belong to oxygen family or group 16. Electronic configuration of oxygen family ends with ns² np⁴, means if the element accommodate 12 electrons, the configuration will become ns² np⁶ nd⁴, which in turn says that element should have d orbitals.

Oxygen and sulfur belongs to period 2 and 3 respectively so they cannot have d orbital. Tellurium belongs to period 5 (same period of Rb), it can extend its configuration to d orbital. So the X element can be "Tellurium " (Te).