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Chemistry Chapter 3 : Topic 12
Isotope Mass and Chemical Properties
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An element has atoms with identical chemical behavior but different masses due to variation in neutrons. What are these atoms called?
Reasoning: Isotopes are atoms of the same element having the same number of protons (hence same chemical properties) but different numbers of neutrons, causing mass differences.
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Why do isotopes of an element show identical chemical properties?
Reasoning: Chemical properties depend on electron configuration, and isotopes have the same number of electrons because they have the same atomic number.
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Which statement correctly explains why isotopes affect molecular mass but not chemical behavior?
Reasoning: Molecular mass changes due to different neutrons, but chemical behavior depends on electrons arranged by atomic number.
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Which pair represents isotopes?
Reasoning: Hydrogen-1 (protium) and Hydrogen-2 (deuterium) are isotopes of hydrogen with different masses but same atomic number.
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Why do isotopes behave identically in chemical reactions?
Reasoning: Chemical reactions depend on proton number (atomic number), which is the same in isotopes.
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A sample of chlorine contains Cl-35 and Cl-37 isotopes. What is affected in chlorine due to this?
Reasoning: Isotopes affect the average atomic mass because of different masses, but chemical properties remain unchanged.
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Which property changes significantly when comparing isotopes of an element?
Reasoning: Isotopes differ in neutrons, so their mass changes, but electronic structure remains the same.
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Heavy water (D₂O) behaves chemically like normal water (H₂O) but differs slightly in physical properties. The reason is:
Reasoning: Deuterium is an isotope of hydrogen; isotopes show same chemical behavior but different mass affects physical properties.
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Which statement is TRUE about isotopes?
Reasoning: Isotopes share the same atomic number and electron arrangement, giving identical chemical properties.
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The existence of isotopes mainly affects which of the following calculations?
Reasoning: Since isotopes differ in mass, compounds containing them show variation in molecular mass.
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Which reason best explains why isotopes cannot be separated by ordinary chemical methods?
Reasoning: Since isotopes behave chemically the same, chemical methods cannot distinguish or separate them.
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Carbon-12 and Carbon-14 behave similarly in chemical reactions because:
Reasoning: Both isotopes have 6 protons, so their chemical behavior is identical.
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Which statement best describes the effect of isotopes on molecular mass?
Reasoning: Different isotopes change the total mass of molecules, creating variation in molecular mass.
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Why is the chemical behavior of isotopes identical despite different masses?
Reasoning: Chemical properties depend on electron arrangement, which is identical in isotopes.
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If an element has isotopes X-10 and X-12, what will remain constant?
Reasoning: Chemical properties remain unchanged because atomic number and electron configuration remain constant.
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Which statement correctly summarizes the concept of isotopes?
Reasoning: Isotopes have different masses due to neutrons but identical chemical properties due to same electrons.
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