Conversations with Henry

Henry: I read your blog post--you forgot about Döbereiner.

Me: Doober-who?

Henry: Döbereiner. Johann Döbereiner. He was before Newlands. He arranged elements into triads.

Me: Huh?

Henry: Triads.

Me: What are triads?

Henry: Döbereiner's Triads. Groups of three elements. All related.

[Henry explains]:

Me: That's pretty scanty.

Henry: So, are we going to play cards or what?

Me: OK.  What are we playing?

Henry: Triads

Henry had a special deck of cards, each one a different chemical element instead of the usual playing card.  I took out everything but the D-block elements (Sc through Hg) shuffled them, and then dealt us each five cards, face down.