CHEMISTRY [5 Mark Question Answer]

Salient features of Dalton’s atomic theory:

1. Matter consists of very small and indivisible particles called atoms, which can neither be created nor can be destroyed.
2. The atoms of an element are alike in all respects i.e. size, mass, density, chemical properties but they differ from the atoms of other elements.
3. Atoms of an element combine in small numbers to form molecules of the element.
4. Atoms of one element combine with atoms of another element in simple whole number ratio to form molecules of compounds.
5. Atoms are the smallest units of matter that can take part in a chemical reaction during which only rearrangement of atoms takes place

Atoms of an element must have the same atomic number, but their mass number can be different due to the presence of a different number of neutrons. These atoms of an element having a different number of neutrons are called groups.
According to Dalton’s theory, all atoms of an element are similar in all respects, for example, they have the same shape, size, etc., and have similar physical and chemical properties like mass, density, and reactivity. Whereas isotopes of an element have atoms that are similar as they have the same number of protons and electrons but differ in the number of neutrons. So, the isotopes have atoms that are not similar in all aspects