Ionisation in radioactive decay of atoms

[Arnav]

There is a question, a satisfactory answer to which I haven't received for long.

      In alpha decay, the number of protons in the parent atom decreases by two while the number of electrons in the atom remains same. Does the parent atom on undergoing alpha decay convert into an anion? 

       In the same way, in beta minus decay, the following transformation takes place :

₀¹n ---->  ₁¹p + e⁻ + v̅

the proton remains in the nucleus and electron and the antineutrino are ejected.

From this, one could conclude that the positive charge on the atom increases by 1 while negative charge remains the same. Does the atom convert into a cation?

Similar is an observation for beta plus decay, which appears to convert the parent atom into an anion.

  Is this ionisation of decaying substance observed in real situations? Or does it not even take place?

[exchemist]

21 minutes ago, Arnav said:

There is a question, a satisfactory answer to which I haven't received for long.

      In alpha decay, the number of protons in the parent atom decreases by two while the number of electrons in the atom remains same. Does the parent atom on undergoing alpha decay convert into an anion? 

       In the same way, in beta minus decay, the following transformation takes place :

₀¹n ---->  ₁¹p + e⁻ + v̅

the proton remains in the nucleus and electron and the antineutrino are ejected.

From this, one could conclude that the positive charge on the atom increases by 1 while negative charge remains the same. Does the atom convert into a cation?

Similar is an observation for beta plus decay, which appears to convert the parent atom into an anion.

  Is this ionisation of decaying substance observed in real situations? Or does it not even take place?

My understanding is yes this is what happens. However the rate of decay is not such as to cause an appreciable bulk charge to accumulate, as a rule - there may be weird exceptions with some exceptionally highly radioactive species, I suppose. There are flows of ions and electrons at very low levels in the atmosphere and in the ground all the time, which we don't notice. 

Edited May 11, 2021 by exchemist

[studiot]

22 minutes ago, exchemist said:

My understanding is yes this is what happens. However the rate of decay is not such as to cause an appreciable bulk charge to accumulate, as a rule - there may be weird exceptions with some exceptionally highly radioactive species, I suppose. There are flows of ions and electrons at very low levels in the atmosphere and in the ground all the time, which we don't notice. 

You are asking this question of the Physicists here.

In most Physcis textbooks the authors are not to worried about charge so the equations presented do not generally observe conservation of charge.

So the equations presented often have a beta minus or alpha positive charge on one side, but no charge on the other.
So these equations do not balance in respect of charge.

For example

Chemists are more careful so here is an extract from a Chemistry textbooks that explains this in detail, balancing the charges as well.

 

 

And yes the equations now balance for charge.
Some reactants and/or products are now shown charged (eg as ions or whatever)

Another way to compare is to understand that Physicists are talking about nuclear reactions and so use the chemical symbols to represent the nucleus, which always carries a positve charge equal to the atom ic number.

Chemists use the same symbols to represent the electrically neutral atom so must always display the charge to refer to an ion.

 

Does this help ?

 

 

Edited May 11, 2021 by studiot

[exchemist]

2 hours ago, studiot said:

You are asking this question of the Physicists here.

In most Physcis textbooks the authors are not to worried about charge so the equations presented do not generally observe conservation of charge.

So the equations presented often have a beta minus or alpha positive charge on one side, but no charge on the other.
So these equations do not balance in respect of charge.

For example

Chemists are more careful so here is an extract from a Chemistry textbooks that explains this in detail, balancing the charges as well.

 

 

And yes the equations now balance for charge.
Some reactants and/or products are now shown charged (eg as ions or whatever)

Another way to compare is to understand that Physicists are talking about nuclear reactions and so use the chemical symbols to represent the nucleus, which always carries a positve charge equal to the atom ic number.

Chemists use the same symbols to represent the electrically neutral atom so must always display the charge to refer to an ion.

 

Does this help ?

 

 

Fat finger trouble? I presume you meant to reply to the OP rather than to me. 

[swansont]

4 hours ago, Arnav said:

Is this ionisation of decaying substance observed in real situations? Or does it not even take place?

Quite often the decays will strip electrons (shake-off electrons) as the charged particle is emitted/ejected.  In alpha and beta decays.

“The charge distributions of several alpha emitters were studied29-33 and they varied from -1 to +10 in the absence of internal conversion.

 Approximately 90% of the recoiling atoms carried zero or +1 charge and the mean charge was less than 1”

https://www.osti.gov/servlets/purl/4262551

So at least 1 shake-off electron, and often 2 or 3. Sometimes more.

[studiot]

2 hours ago, exchemist said:

Fat finger trouble? I presume you meant to reply to the OP rather than to me. 

Yes, sorry.

Quoting you instead of the OP was my mistake.

 

[exchemist]

9 hours ago, studiot said:

Yes, sorry.

Quoting you instead of the OP was my mistake.

 

Maa fiy sweat.  

[John Cuthber]

On 5/11/2021 at 6:49 PM, Arnav said:

Does the atom convert into a cation?

Sometimes.

 

https://pubs.acs.org/doi/abs/10.1021/ja01009a040

But usually the energy released tears up the ions involved.

[Arnav]

On 5/11/2021 at 11:58 PM, studiot said:

Does this help ?

It definitely does! Thanks

22 hours ago, John Cuthber said:

But usually the energy released tears up the ions involved.

Hey cuthber, could you please elaborate what do you mean by this?

[John Cuthber]

Say you have some uranium (VI) fluoride UF₆, and it decays.

It spits out a helium nucleus and forms Thorium and helium.

But the helium nucleus is shot at at a huge speed.

So, according to the conservation of momentum,  the Thorium nucleus must be kicked the other way by the recoil.

It is usually set moving so fast that most of the fluoride ions simply get left behind. Indeed, most of the outer electrons get left behind too

So you get a mess of fluorine, helium, thorium  (as ions) and electrons all moving in different directions.

 

 

[Arnav]

On 5/13/2021 at 11:26 PM, John Cuthber said:

Say you have some uranium (VI) fluoride UF₆, and it decays.

It spits out a helium nucleus and forms Thorium and helium.

But the helium nucleus is shot at at a huge speed.

So, according to the conservation of momentum,  the Thorium nucleus must be kicked the other way by the recoil.

It is usually set moving so fast that most of the fluoride ions simply get left behind. Indeed, most of the outer electrons get left behind too

So you get a mess of fluorine, helium, thorium  (as ions) and electrons all moving in different directions.

 

 

Oh ok I understood. Thanks !