Question7. Given a portion of the periodic table below, write the complete equation for the alpha decay of Plutonium-242. \begin{tabular}{|c|c|c|c|c|c|c|c|} \hline & & & & & & & \\ \hline \end{tabular} [3]
Studdy Solution
STEP 1
What is this asking?
We need to write a balanced nuclear equation showing how Plutonium-242 transforms after emitting an alpha particle.
Watch out!
Remember that the total number of protons and neutrons must be conserved in a nuclear reaction.
Don't forget the mass number and atomic number of an alpha particle!
STEP 2
1. Define alpha decay
2. Identify Plutonium
3. Balance the equation
STEP 3
Alpha decay happens when a nucleus spits out an alpha particle.
It's like the nucleus is saying, "I'm too big, let me shed some weight!" An alpha particle is basically a Helium-4 nucleus, written as \(_{2}^{4}\text{He}\).
It has **2 protons** and **2 neutrons**, so a total mass number of **4**.
STEP 4
Plutonium-242 is written as \(_{94}^{242}\text{Pu}\).
This means it has **94 protons** and \ **148 neutrons**.
We're starting with this and an alpha particle will come flying out!
STEP 5
We start with Plutonium-242: \(_{94}^{242}\text{Pu}\) and it decays into an unknown element plus an alpha particle: \(_{2}^{4}\text{He}\).
We can write this as:
\(_{94}^{242}\text{Pu} \rightarrow _{Z}^{A}\text{X} + _{2}^{4}\text{He}\) where is the unknown element, is its mass number, and is its atomic number (number of protons).
STEP 6
The total number of protons and neutrons must be the same on both sides of the equation.
For the mass numbers, we have:
STEP 7
For the atomic numbers (protons), we have:
STEP 8
So, our unknown element has a mass number of **238** and an atomic number of **92**.
Looking at the periodic table provided, element number 92 is **Uranium (U)**.
Awesome!
STEP 9
The complete, balanced equation for the alpha decay of Plutonium-242 is:
\(_{94}^{242}\text{Pu} \rightarrow _{92}^{238}\text{U} + _{2}^{4}\text{He}\)
Was this helpful?
