Arrange the following elements in decreasing order of atomic size.
Element: 'A' → Atomic number is 7.
Element: 'B' → Atomic number is 3.
Element: 'C' → Atomic number is 9.
Element: 'D' → Atomic number is 11.
Arrange the following elements in decreasing order of atomic size.
Element: 'A' → Atomic number is 7.
Element: 'B' → Atomic number is 3.
Element: 'C' → Atomic number is 9.
Element: 'D' → Atomic number is 11.
The correct option is B DBAC
The explanation for the correct option B):
- Atomic radius is defined as the distance from the centre of the nucleus of the atom to its outermost shell.
- Trend of atomic radius in a group: The atomic radii of elements steadily increase from top to bottom in a group. As we progress down a group, the atomic number rises, and the number of shells rises with it.
- Trend of atomic radius across a period: The atomic radii steadily decrease as we move from left to right across a period because the nuclear charge gradually increases from left to right. The electron enters the same shell as the atomic number increases. As a result, they become increasingly drawn to the nucleus. The atomic radii gradually decrease as a result of the increased nucleus's force of attraction.
- Element: 'A' → Atomic number is 7: The element is Nitrogen and it belongs to period 2.
Element: 'B' → Atomic number is 3: The element is Lithium and it belongs to period 2.
Element: 'C' → Atomic number is 9: The element is fluorine and it belongs to period 2.
Element: 'D' → Atomic number is 11: The element is Sodium and it belongs to period 3.
5. The elements ‘A’, ‘B’, and ‘C’ belong to period two. For all elements in period 2, As the atomic number of the elements increases, the atomic radius of the elements decreases. Thus the decreasing order for period 2 atomic radius is Li > N > F or B > A > C.
6. The element ‘A’ and ‘D’ belongs to the first group and down the group atomic radius increases. Thus, Na (D) > N (A)
7. Hence, the decreasing order of atomic size is D > B >A>C.
Hence, option (B) is correct.
DBAC
The explanation for the correct option B):
- Atomic radius is defined as the distance from the centre of the nucleus of the atom to its outermost shell.
- Trend of atomic radius in a group: The atomic radii of elements steadily increase from top to bottom in a group. As we progress down a group, the atomic number rises, and the number of shells rises with it.
- Trend of atomic radius across a period: The atomic radii steadily decrease as we move from left to right across a period because the nuclear charge gradually increases from left to right. The electron enters the same shell as the atomic number increases. As a result, they become increasingly drawn to the nucleus. The atomic radii gradually decrease as a result of the increased nucleus's force of attraction.
- Element: 'A' → Atomic number is 7: The element is Nitrogen and it belongs to period 2.
Element: 'B' → Atomic number is 3: The element is Lithium and it belongs to period 2.
Element: 'C' → Atomic number is 9: The element is fluorine and it belongs to period 2.
Element: 'D' → Atomic number is 11: The element is Sodium and it belongs to period 3.
5. The elements ‘A’, ‘B’, and ‘C’ belong to period two. For all elements in period 2, As the atomic number of the elements increases, the atomic radius of the elements decreases. Thus the decreasing order for period 2 atomic radius is Li > N > F or B > A > C.
6. The element ‘A’ and ‘D’ belongs to the first group and down the group atomic radius increases. Thus, Na (D) > N (A)
7. Hence, the decreasing order of atomic size is D > B >A>C.
Hence, option (B) is correct.
