How many carbon, hydrogen, oxygen, nitrogen, and phosphorus atoms are there in the observable universe?

If I could somehow reliably count all the carbon, nitrogen, hydrogen, oxygen, and phosphorus atoms in the observable universe, what number would I come up with?




Two key numbers can be estimated from known observable things in astronomy (and cosmology where current big bang models explain the processes that created the "light" elements and their abundance and observations broadly agree with theory). Spectroscopy allow astronomers to estimate the abundance of many elements in stars and galaxies.


There are also some estimates of how many nuclei there are (based on estimates of the mass of the observable universe.


We can combine the estimates about the number of nuclei with their relative abundance to give some approximate counts for elements.


The number of nuclei [is estimated to be](https://www.universetoday.com/36302/atoms-in-the-universe/) between $\pu{10^78}$ and $\pu{10^82}$ (which are both crazy big numbers though the upper estimate is 10,000 times the lower estimate so don't expect precision).


But we also understand the relative abundance, though most estimates count mass proportion (counting nucleons not atoms). Using [the numbers in Wikipedia](https://en.wikipedia.org/wiki/Abundance_of_the_chemical_elements) and adjusting the estimates for the mass of each elemental nucleus gives the following proportions:


H 92%   

He 7.5%   

O 0.08%   

C 0.05%   

N 0.01%


If we take the mid estimate of total nuclei as $\pu{10^80}$ then there are approximately $\pu{8E76}$ oxygen atoms, $\pu{5E76}$ carbon atoms and $\pu{1E76}$ nitrogen atoms in the observable universe (if I've done my maths right).


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