Question

Define :
a)Isobars
b)Isotones
c)Isotopes
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Answer 1

Isobars

• Isotopes are elements which have the same mass number but differ in their atomic number.

• Isobars are the atoms of different elements and they possess different physical and chemical properties.
• Isobars were discovered by Alfred Walter Stewart in 1918.
• Examples-

a) ₁H³ and ₂He³

b) ₁₈Ar⁴⁰, ₁₉K₄₀ and ₂₀Ca⁴⁰

Isotones

• Isotones are the atoms of different elements having same number of neutrons but different mass numbers.
• Isotones were discovered by K. Guggenheimer in 1899.
• Examples-

a) ₁H³ and ₂He⁴

b) ₁₅P³¹ and ₁₆S³²

c) ₁₉K⁴⁰ and ₂₀Ca⁴⁰  

Isotopes

• Isotopes are elements which have the same atomic number but differ in their mass number.
• Isotopes have identical chemical properties but differ in physical properties.
• Isotopes were discovered by Frederick Soddy in 1913.
• Examples-

a) ₁H¹(Protium), ₁H²(Deuterium), ₁H³(Tritium)

b) ₈O¹⁶, ₈O¹⁷, ₈O¹⁸

Answer 2

Answer:

Atoms of different elements with different atomic numbers but the same mass numbers are called isobars.Isobars have different chemical properties because they have different atomic numbers.