an element with the following electron configuration will gain ____________ electrons to form a common ion…

an element with the following electron configuration will gain ____________ electrons to form a common ion. 1s² 2s² 2p⁶ 3s² 3p³\n4\n2\n1\n3\nquestion 4\n1 pts\nthe electron configuration for se²⁻ is ____________ which is isoelectronic with ____________.\nar5s² 4d¹⁰ 5p⁶, xenon\nar4s² 3d¹⁰ 4p⁴, krypton\nar4s² 3d¹⁰ 4p⁶, krypton\nar4s² 3d¹⁰ 4p⁶, argon

an element with the following electron configuration will gain ____________ electrons to form a common ion. 1s² 2s² 2p⁶ 3s² 3p³\n4\n2\n1\n3\nquestion 4\n1 pts\nthe electron configuration for se²⁻ is ____________ which is isoelectronic with ____________.\nar5s² 4d¹⁰ 5p⁶, xenon\nar4s² 3d¹⁰ 4p⁴, krypton\nar4s² 3d¹⁰ 4p⁶, krypton\nar4s² 3d¹⁰ 4p⁶, argon

Answer

Explanation:

Step1: Analyze the first electron - configuration

The electron - configuration is (1s^{2}2s^{2}2p^{6}3s^{2}3p^{3}). The outermost shell is the third shell ((n = 3)) with (2 + 3=5) electrons in the (3s) and (3p) sub - shells. Elements tend to gain or lose electrons to achieve a noble - gas electron configuration. The nearest noble gas is argon ((1s^{2}2s^{2}2p^{6}3s^{2}3p^{6})), so this element will gain (3) electrons to fill the (3p) sub - shell.

Step2: Analyze the electron - configuration of (Se^{2-})

Selenium ((Se)) has an atomic number of (34), so its neutral electron - configuration is ([Ar]4s^{2}3d^{10}4p^{4}). When it forms (Se^{2-}), it gains (2) electrons. The electron - configuration of (Se^{2-}) is ([Ar]4s^{2}3d^{10}4p^{6}). Krypton ((Kr)) has an electron - configuration of ([Ar]4s^{2}3d^{10}4p^{6}), so (Se^{2-}) is isoelectronic with krypton.

Answer:

  1. D. 3
  2. C. ([Ar]4s^{2}3d^{10}4p^{6}), krypton