# Homework Help: Determining the atomic number, mass number, and chemical name during beta decay

1. Dec 9, 2012

### Hannah1

Determining the atomic number, mass number, and chemical name during beta decay!!

1. The problem statement, all variables and given/known data
The image below shows the element Thorium with the atomic number listed above and a mass number of 233. This element undergoes two successive beta decays. The resulting nucleus will have an atomic number of (1) __________ and a mass number of (2) __________. The chemical name for the nucleus is (3) __________.
(BTW, there was no image shown in the homework, but it can be implied that the the atomic number of Thorium is 90.)

2. Relevant equations
Thorium (Atomic Number = 90)

3. The attempt at a solution
(1) 92
(2) 233
(3) Uranium-233

I submitted these answers on my homework, but I only got 2/3 correct, meaning one of my answers was wrong. What answer was wrong??
Could it be that #3 should just be Uranium (I'm not sure what a chemical name is...)?

2. Dec 9, 2012

### Hannah1

Re: Determining the atomic number, mass number, and chemical name during beta decay!!

It should be an easy problem to figure out, but I can't find out how to do it! :(
I feel stupid.

3. Dec 10, 2012

### Pappers08

Re: Determining the atomic number, mass number, and chemical name during beta decay!!

What kind of Beta Decay is this? There are usually two kinds, where there is a positive emission or a negative emission. That might be where you made your error.

4. Dec 10, 2012

### cosmic dust

Re: Determining the atomic number, mass number, and chemical name during beta decay!!

If it was positive emission then both (1) and (3) would be wrong. So it is negative emission. Maybe the your mistake was that you did not considered that uranium will be charged, since the production of two protons will increase the nucleus charge by 2e and since there is no addition of extra electrons (the electrons from the decay escape from the atom), tha net charge after the decay will be +2e. So, (3) should be $^{233}_{92}$U+2

5. Dec 11, 2012

### Hannah1

Re: Determining the atomic number, mass number, and chemical name during beta decay!!

It turns out that the correct answer for #3 is "Uranium."
You don't have to add the number at the end.

6. Dec 11, 2012

### Pappers08

Re: Determining the atomic number, mass number, and chemical name during beta decay!!

Well I'm glad you fixed the mistake!