Name: Valencies of Some Common Ions
Uploaded: 2019-07-19
Duration: 4 min 56 s
Description: Ionic compounds are composed of positively charged and negatively charged ions. Do you know what the charges on these ions are called? Let’s find out in this...

Question

What are the drawbacks of Dalton's atomic theory?

Accepted Answer

Drawbacks of Dalton's atomic theory:

1. Atom is no longer considered as the smallest indivisible particle. Towards the end of the $19^{th}$ century, it was found that an atom was composed of still smaller subatomic particles such as electron, proton and neutron.

2. Atoms of the same element have different masses. For example, chlorine has two types of atoms with masses $35 u$ and $37 u$ . Such atoms of an element with different masses are called isotopes.

3. Atoms of some different elements have the same masses. The atoms of different elements with the same mass numbers are called isobars. For example, the atoms of potassium and calcium have the same mass number $(40) .$

4. Substances made up of same kind of elements have different properties. For example, diamond, graphite and charcoal are made up of carbon atoms, but they possess different physical properties.

5. The ratio in which the different atoms combine to form a compound is fixed and integral but may not be simple. For example, a molecule of sugar having the formula $C_{12} H_{22} O_{11}$ contain $C, H and O$ in the ratio $12 : 22 : 11$ . The ratio is fixed and integral but is not simple.

What are the drawbacks of Dalton's atomic theory?

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