Question

What equation would I use for this? —> Uranium-233 undergoes alpha decay

Answer 1

₉₂²³³U ⟶ ₉₀²²⁹Th + $_2^4He$

Your equation is:  

₉₂²³³U ⟶ ? + α

It becomes easier to balance the equation if we replace the "?" with an element symbol _x^yZ.

Then the equation becomes

₉₂²³³U ⟶ _x^yZ + α

We should also recall that a α particle is helium nucleus. Its nuclear symbol is $_2^4He$.

The equation then becomes

₉₂²³³U ⟶ _x^yZ + $_2^4He$

The main point to remember in balancing nuclear equations is that **the sums of the superscripts and the subscripts must be the same on each side of the equation**.

Sum of superscripts: 233 = y + 4, so y =229.

Sum of subscripts:       92 = x + 2, so x = 90.

₉₂²³³U ⟶ ₉₀²²⁹Z + $_2^4He$

The element with atomic number 90 is thorium, Th.

∴ The nuclear equation is

₉₂²³³U ⟶ ₉₀²²⁹Th + $_2^4He$