Write four modification of John Dalton atomic theory
1) Modification 1: Dalton's theory stated that atoms are indivisible and indestructible, but this has been modified by the discovery of subatomic particles such as electrons, protons, and neutrons. We now know that atoms are composed of these smaller particles and can undergo nuclear reactions, such as fusion or fission.
2) Modification 2: Dalton's theory proposed that all atoms of the same element are identical, but we now understand that atoms of the same element can have different numbers of neutrons, leading to the existence of isotopes. For example, carbon-12 and carbon-14 are both isotopes of carbon with different numbers of neutrons.
3) Modification 3: Dalton's theory assumed that atoms of different elements have different masses. However, it was later discovered that atoms of different elements can have similar masses, leading to the concept of isotopes. For example, oxygen-16 and sulfur-32 have similar masses despite being different elements.
4) Modification 4: Dalton's theory suggested that all compounds are formed by the combination of whole atoms in fixed ratios. However, modern chemistry has revealed that compounds can have varying ratios and even incomplete combinations, leading to the concept of molecular formulas and the existence of ions. For example, the compound water (H2O) consists of two hydrogen atoms and one oxygen atom, but there are also compounds like hydrochloric acid (HCl) where only one hydrogen atom is combined with one chlorine atom.