# A riddle that is first of its kind

My first, yet simple, puzzle on this site.

By myself, I’m as light as can be

But throw me a ball, and suddenly I’ll be heavy

Give me another, and I’ll get quite excited

Because shortly thereafter, I will become a he instead.

What am I?

• The title needs to be more specific. – Peter Mortensen Aug 23 '18 at 23:41
• @PeterMortensen My intention was to make the title have a very obvious clue. – T James Aug 24 '18 at 14:07
• I don't know if it's just me, but $\ast$ (ROT13) jura lbh fnvq "ur", V qvqa'g guvax bs n znyr; V gubhtug bs "Ur" nf va "Uryvhz", naq gur "rkpvgrq" cneg znqr zr n yvggyr zber vagrerfgrq. V gura terj rkpvgrq zlfrys, hagvy V fnj @EnaqNyGube'f nafjre... V guvax guvf cneg jnf gur ovt tvirnjnl, naq abg gur gvgyr. Ohg V yvxr culfvpf... $\ast$ Great puzzle, nonetheless! I have reached my daily voting limit and have to wait $9$ hours before I can vote again (DVL9), so I have favourited instead $\color{darkorange}{\bigstar}$ :D – Mr Pie Aug 24 '18 at 14:25
• I don't think there's anything wrong with the original title, just FTR. It's part of the nature of Puzzling that we have a lot of puzzles with 'unspecific' titles. – Rand al'Thor Aug 24 '18 at 14:59
• @Randal'Thor I don't mind the titles in a puzzle. I usually ignore them and then once I believe I have solved the answer, I explain the title last. (Even when I make my own riddles/puzzles, I leave the title 'til last.) :P – Mr Pie Aug 24 '18 at 15:12

Are you

a hydrogen atom/nucleus?

By myself, I’m as light as can be

Hydrogen is the lightest element on the periodic table. Specifically, this would refer to the standard isotope of protium, with just a single proton in the nucleus.

But throw me a ball, and suddenly I’ll be heavy

Deuterium, a hydrogen isotope with one proton and one neutron, is called heavy water.

Give me another, and I’ll get quite excited

Tritium, a hydrogen isotope with one proton and two neutrons, is in an excited state ...

Because shortly thereafter, I will become a he instead.

... and soon decays into helium-3, denoted by "He" on the periodic table.

Feedback section

I think the word "excited" was the first key for me in solving this. That word seems likely to have a non-obvious meaning that fits the context of whatever the solution is, and the only second meaning I could think of was in physics. From the first line I guessed the answer might be a photon, so I spent a while barking up that tree and thinking about particle interactions involving photons on Feynman diagrams. Then I realised what the "he" must mean, and from there it was easy to construct the right answer after a quick look at a list of isotopes on Wikipedia.

• I see we have similar lines of thinking. – Joe-You-Know Aug 23 '18 at 15:56
• Apparently too easy.. You guys sure are fast! – T James Aug 23 '18 at 15:59
• @Joe-You-Know I had to think for a minute to be sure, but I think I just beat you to it :-) Have a +1. – Rand al'Thor Aug 23 '18 at 15:59
• @jwi You get my +1 as well :-) – Rand al'Thor Aug 23 '18 at 16:06
• I should add that you are the only one who truly got the heavy reference correct. Impressive in such a short amount of time. – T James Aug 23 '18 at 16:09

Are you:

Hydrogen (nucleus)

By myself, I’m as light as can be

Lowest atomic weight from all the elements

But throw me a ball, and suddenly I’ll be heavy

Add an electron, atomic weight increases

Give me another, and I’ll get quite excited

Add more electrons or even a proton+neutron, it will go through chemical change

Because shortly thereafter, I will become a he instead.

From that, it becomes He, helium

• Really close, but missed the heavy reference just a bit. – T James Aug 23 '18 at 16:24

You are an

electron

By myself, I’m as light as can be

Electrons have essentially as little mass as possible without being massless

But throw me a ball, and suddenly I’ll be heavy

the ball is a proton (or a proton-neutron pair)

Give me another, and I’ll get quite excited

Then you will be a helium ion

Because shortly thereafter, I will become a he instead.

helium ions are so good at stabilizing that it will pull an electron from somewhere and become stable. He is the atomic symbol for helium

• Not exactly what I was thinking, but I am impressed that you actually came up with an alternate answer for what I thought was a rather specific riddle. +1! – T James Aug 23 '18 at 16:05

Are you

Hydrogen?

By myself, I’m as light as can be

Hydrogen is the lightest element.

But throw me a ball, and suddenly I’ll be heavy

I believe this is referring to adding a neutron to the hydrogen atom. It'll make tritium, which makes it nearly twice as heavy.

Give me another, and I’ll get quite excited