Understanding Fajans Rule: Ion Depletion & Valency Change

In summary, Fajan's rule states that the valency of a substance can change after emitting alpha or beta rays due to the change in its ionic composition. This is because it is easier to change the electronic composition compared to the nuclear composition. Therefore, the resulting ion will attract or lose the necessary number of electrons to maintain neutrality. This concept can be applied to understand the changes in valency before and after the emission of alpha and beta rays.
  • #1
loza17
2
0
fajans rule??

hey can anyone help me with fajans rule?

after the emission of alpha rays from a radioactive substance the product remaining has a valency of 2. after the emission of beta rays it has a valency increase of 1. so the ionic depletion changes the valency.

thus meaning reducing the ions changes the valency

is this right?
 
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  • #2
What does this have to do with Fajan's rules?

In any case, the important thing to keep in mind is that it is harder to change the nuclear composition (number of protons and neutrons) than the electronic composition. Once the number of protons is changed, the resulting ion will attract or throw away the necessary number of electrons to stay neutral. So, if the atom gains/loses n protons through radioactive decay, it will then pick up/throw out n electrons as well.

With this in mind, make sure you can follow what is happening with the atom above. What would have been the valency before alpha emission? Do the subsequent changes in valency make sense?
 
  • #3
thats what my tutor taught me and i was confused about it. thanks for the help =]
 

FAQ: Understanding Fajans Rule: Ion Depletion & Valency Change

1. What is Fajans rule and why is it important in chemistry?

Fajans rule is a set of guidelines that helps predict the formation of covalent bonds between two ions. It states that smaller, highly charged cations and larger, highly charged anions will have a greater tendency to form covalent bonds. This rule is important in chemistry because it helps us understand the forces that govern chemical bonding and allows us to predict the properties of compounds.

2. How does Fajans rule affect ion depletion?

Fajans rule states that highly charged cations will have a greater tendency to form covalent bonds. This means that as the charge on a cation increases, its ability to attract and hold onto electrons decreases. As a result, the cation will become more polarizable, leading to a depletion of ions in the surrounding solution.

3. Can Fajans rule explain valency change in ions?

Yes, Fajans rule can explain valency change in ions. According to the rule, highly charged cations and anions have a greater tendency to form covalent bonds. As a result, the valency of these ions can change in a compound due to the sharing of electrons in a covalent bond. This can result in the formation of compounds with different valencies than the individual ions.

4. How does Fajans rule affect the properties of compounds?

Fajans rule can affect the properties of compounds in several ways. Firstly, it can determine the type of bonding present in a compound, whether it is ionic or covalent. Secondly, it can affect the strength of the bond between ions, with covalent bonds being stronger than ionic bonds. Thirdly, it can also impact the physical properties of compounds, such as melting and boiling points, solubility, and conductivity.

5. Are there any exceptions to Fajans rule?

Yes, there are some exceptions to Fajans rule. For example, the rule does not apply to compounds with highly electronegative atoms, such as fluorine, as they can form strong covalent bonds with almost any cation. Additionally, the rule only applies to ionic compounds and may not accurately predict the behavior of covalent compounds. Lastly, the size and charge of the ions may also affect the validity of Fajans rule in certain cases.

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