Question

Give postulates of Dalton's atomic theory

Answer 1

The main postulates of Dalton's Atomic theory -

• Every matter in this universe is made up of tiny particles called atoms.

• Atoms are the individual particles which can neither be created nor be destroyed.

• Atoms of a given element are equal in mass as well as in chemical properties.

• Atoms have different chemical properties and different masses of different elements.

• Atoms mix in the ratio of small whole numbers to form compounds.

• In a given compound the relative numbers and sets of atoms are constant.

Answer 2

$\underline{\textbf{QUESTION :-}}$

Give postulates of Dalton's atomic theory

$\underline{\textbf{ANSWER :-}}$

The Merits of Dalton’s Atomic Theory

1. The law of multiple proportions, the law of conservation of mass, and the law of constant proportions are not violated by Dalton’s atomic theory.
2. The theory provides a basis to differentiate between elements and compounds.

Postulates of Dalton’s Atomic Theory

• All matter is made up of tiny, indivisible particles called atoms.

• All atoms of a specific element are identical in mass, size, and other properties. However, atoms of different element exhibit different properties and vary in mass and size.

• Atoms can neither be created nor destroyed. Furthermore, atoms cannot be divided into smaller particles.

• Atoms of different elements can combine with each other in fixed whole-number ratios in order to form compounds.

• Atoms can be rearranged, combined, or separated in chemical reactions.

Limitations of Dalton’s Atomic Theory

• It does not account for subatomic particles: Dalton’s atomic theory stated that atoms were indivisible. However, the discovery of subatomic particles (such as protons, electrons, and neutrons) disproved this postulate.

• It does not account for isotopes: As per Dalton’s atomic theory, all atoms of an element have identical masses and densities. However, different isotopes of elements have different atomic masses (Example: hydrogen, deuterium, and tritium).

• It does not account for isobars: This theory states that the masses of the atoms of two different elements must differ. However, it is possible for two different elements to share the same mass number. Such atoms are called isobars (Example: ⁴⁰Ar and ⁴⁰Ca).

• Elements need not combine in simple, whole-number ratios to form compounds: Certain complex organic compounds do not feature simple ratios of constituent atoms. Example: sugar/sucrose (C₁₁H₂₂O₁₁).

• The theory does not account for allotropes: The differences in the properties of diamond and graphite, both of which contain only carbon, cannot be explained by Dalton’s atomic theory.