# Chemistry

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Write a balanced nuclear equation for the positron emission of each of the following nuclei: a) arsenic-74
b) oxygen-15

• Chemistry - ,

The secret to these is to write an equation in which the subscripts add up on both sides and the superscripts add up on both sides. Subscripts and superscripts are a problem on the board so this is the way I will show it.
8O15 means oxygen with an atomic number of 8 and a mass of 15
33As74 means As with an atomic number of 33 and a mass of 74

A positron is the same as an elecrron but with a positive charge so we write it as 1e0.

8O15 ==> 1e0 + X
So 8 on the reactant side = 1 + something on the product side. What is something? That must be 7 because 7+1 on the product side = 8 on the reactant side.
What about the superscripts; i.e., the numbers on the right. 15 on the reactant side = 0 on the product side + something. That something must be 15 because 15+0 = 15. Now what is element X? The atomic number is 7 so that makes it N. Look at the periodic table to confirm that.