The first and second energy levels of a neutral atom are full, and the third energy level contains three electrons. To which group does this element belong?

Question

The first and second energy levels of a neutral atom are full, and the third energy level contains three electrons. To which group does this element belong??  
A. Group 3  
B. Group 8  
C. Group 10  
D. Group 13

Accepted Answer

Correct Answer: (D)Group 13. 
Rationale: This element belongs to Group 13.The group number for main group elements (Groups 1, 2, and 13-18 in the modern IUPAC numbering) generally indicates the number of valence electrons. Valence electrons are those in the outermost principal energy level (highest n value) and are primarily responsible for an element's chemical properties.A) Group 3In the modern periodic table, Group 3 contains the scandium family (Sc, Y, La, Ac), which are transition metals. Their electron configurations involve filling inner d-orbitals, and their group number does not simply correspond to a count of s and p valence electrons. An atom with the described configuration is not a transition metal in Group 3.B) Group 8Group 8 contains iron, ruthenium, osmium, and hassium transition metals. The noble gases, which have full valence shells, are in Group 18. An atom with only three electrons in its third shell does not have a full outer shell, so it cannot be a noble gas. The number 8 does not correspond to the valence electron count of the described atom.C) Group 10Group 10 contains nickel, palladium, platinum, and darmstadtium more transition metals. Their chemistry is dominated by d-electrons. The described electron configuration points to a main group element, not a Group 10 transition metal.D) Group 13The description gives a specific electron configuration. "First and second energy levels are full" means: First level (n=1): holds max 2 electrons (1s²). Second level (n=2): holds max 8 electrons (2s²2p⁶). "Third energy level contains three electrons" means the configuration continues as 3s²3p¹. Therefore, the full electron configuration is 1s² 2s² 2p⁶ 3s² 3p¹. The valence electrons are those in the highest principal energy level (n=3): the 3s² and 3p¹ electrons, totaling 3 valence electrons. Elements with three valence electrons reside in Group 13. Examples include boron (B), aluminum (Al), gallium (Ga), etc. Aluminum, for instance, has the exact configuration [Ne] 3s² 3p¹.Conclusion:By determining the number of valence electrons from the described electron occupancy, we find the atom has three valence electrons. In the modern periodic table, elements with three valence electrons in their outermost s and p orbitals are classified in Group 13.

The first and second energy levels of a neutral atom are full, and the third energy level contains three electrons. To which group does this element belong?

A
Group 3

B
Group 8

C
Group 10

D
Group 13

This element belongs to Group 13.

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The first and second energy levels of a neutral atom are full, and the third energy level contains three electrons. To which group does this element belong?

A Group 3 B Group 8 C Group 10 D Group 13

This element belongs to Group 13.

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Related Questions

A
Group 3

B
Group 8

C
Group 10

D
Group 13