Question

There are 3 shells in the atom of element X. 6 electrons are present in its outermost shell. In which group is the element included ?

• A. 6
• B. 5
• C. 16
• D. 10

Answer 1

Answer:

C. 16

Understanding Element Placement in the Periodic Table

• The arrangement of elements in the modern periodic table is based on their atomic number and electron configuration, which helps in predicting their chemical properties.
• Elements are organized into periods (horizontal rows) and groups (vertical columns).

Determining the Period of an Element

• The number of shells (or energy levels) an atom possesses directly corresponds to its period number in the periodic table.
• In this case, element X has 3 shells, meaning it belongs to the 3rd period.

Determining the Group of an Element

• The group number of an element is primarily determined by the number of valence electrons (electrons in the outermost shell).
• For main group elements (s-block and p-block elements), the rules are as follows:
  • If the outermost shell contains 1 or 2 electrons (s-block elements), the group number is directly equal to the number of valence electrons (Group 1 or Group 2).
  • If the outermost shell contains 3 to 8 electrons (p-block elements), the group number is calculated by adding 10 to the number of valence electrons.
• Since element X has 6 electrons in its outermost shell, it is a p-block element.
• Therefore, its group number is 10 + 6 = 16.

Key Facts about Group 16 Elements (Chalcogens)

• Group 16 elements are commonly known as Chalcogens. The term 'chalcogen' means 'ore-forming' because many of them are found in ores.
• This group includes Oxygen (O), Sulfur (S), Selenium (Se), Tellurium (Te), and Polonium (Po). Livermorium (Lv) is a synthetic radioactive element also in this group.
• Elements in this group typically exhibit an oxidation state of -2, especially oxygen, due to their tendency to gain two electrons to achieve a stable octet configuration. Other common oxidation states include +2, +4, and +6 for heavier members.
• Understanding electron configuration is crucial for competitive exams as it helps in predicting an element's chemical reactivity, valency, and position in the periodic table.