Question

The existence of isotopes violates one of the original ideas of Dalton’s atomic theory. Which one?

a) The Law of Definite Proportions.

b) The Law of Conservation of Mass.

c) Atoms are indivisible and indestructible.

d) Atoms of different elements combine in simple, whole-number ratios to form compounds.

Answer 1

The existence of isotopes contravenes Dalton's second postulate that atoms of a particular element are identical in all respects, as isotopes demonstrate atoms of the same element can have different masses.

Step-by-step explanation:

The existence of isotopes contradicts the original idea from Dalton's atomic theory that all atoms of a particular element have identical properties, including mass. This idea specifically violated Dalton's second postulate, which asserted that atoms of the same element are identical in all respects. The discovery of isotopes showed that atoms of the same element can have different masses. To reconcile this, the postulate was revised to state that atoms of the same element must have identical chemical properties, despite possibly differing in mass.

Dalton's atomic theory stated that all atoms of a particular element had identical properties, including mass. However, the discovery of isotopes showed that atoms of the same element can have different masses, which violated this postulate of Dalton's theory. Isotopes are atoms of the same element with different numbers of neutrons. For example, chlorine has two isotopes with mass numbers 35 and 37.