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Twink_Ass_Bitch t1_jcbu73r wrote

Reply to comment by honey_102b in Radon is a monatomic gas, but its decay products are solids. After a decay, what happens to the individual atoms of the daughter elements? Do they stay suspended in the atmosphere or slowly rain out? by foodtower

Isolated metal atoms are actually very reactive compared to metal atoms bound in a bulk solid phase. It wouldn't surprise me if a lead atom would spontaneously react with gases in the atmosphere.

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Bbrhuft t1_jcdzt3r wrote

The radon progeny, Bi-214 and Pb-214 do not react with oxygen, except sometimes Po-218.

They start off are singly ionized ions (Po+, Pb+, Bi+). As a result, reactions with Volatile Organic Compounds (VOCs), which commonly contaminates air, especially indoor air, is favoured over oxygen. They also react with hydroxyl radicals, ionized water vapour that's formed in the ionization trail of their recoil path (Po-218 recoils at 13 million mph, after Radon-222 emits an Alpha particle travelling at 7% the speed of light).

These reactions form minute particles, 1.2 to 2 nm in diameter, likely consisting of clusters of 5 to 8 water molecules and a few molecules of VOCs surrounding a now neutral atom of Pb or Bi.

That said, some Po-218 ions react to form Po oxide. This is shown by a double peak in measured particle size distribution of radon Po progeny particles; Po forms a double peak, smaller particles of PoOx of 0.5 - 1.5 nm and much lager particles (c. 15 nm) of a Po atom surrounded by SO2, water and VOC molecules much larger than Bi-214 and Pb-214 clusters.

Castleman Jr, A.W., 1991. Consideration of the chemistry of radon progeny. Environmental science & technology, 25(4), pp.730-735.

Hopke, P., 1996. The initial atmospheric behavior of radon decay products. Journal of Radioanalytical and Nuclear Chemistry, 203(2), pp.353-375.

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