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The isotope of an unknown element, X, has a mass number of 79. The most stable ion of the isotope has 36 electrons and forms a binary compound with sodium having a formula of Na2X. Which of the following statements is(are) true? For the false statements, correct them. a. The binary compound formed between X and fluorine will be a covalent compound. b. The isotope of X contains 38 protons. c. The isotope of X contains 41 neutrons. d. The identity of X is strontium, Sr.

User Cephas
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Final answer:

The true parts of the statements are that the binary compound formed with fluorine will be ionic and that isotope X contains 41 neutrons. The false statements were corrected to show that X has 43 protons, 36 neutrons, and is actually element Selenium (Se).

Step-by-step explanation:

The isotope of an unknown element, X, has a mass number of 79 and its most stable ion has 36 electrons when it forms a binary compound with sodium, with a formula of Na2X. Considering this information:

  • a. The binary compound formed between X and fluorine will not be a covalent compound. It will likely be an ionic compound because X seems to be a metal (as it forms an ionic compound with sodium).
  • b. The isotope of X contains not 38 but 43 protons, since the most stable ion of X has 36 electrons and a negative charge, implying it lost electrons compared to its neutral state.
  • c. The isotope of X does contain 41 neutrons. If the mass number is 79 and there are 43 protons, subtracting 43 from 79 gives us 36, but considering the ion has lost 2 electrons to bond with 2 sodium atoms, it must have 43 protons; thus, 79 - 43 = 36 neutrons.
  • d. The identity of X is not strontium, Sr. Given that the most stable ion of X has 36 electrons, which is 2 fewer than its neutral state, the element X must be Selenium (Se), which in its neutral state has 34 electrons and an atomic number of 34.

User Obaidullah
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