I know the elements articles are a PITA and involve a lot of defense from vandals and WP:NOR failers- it's not something I want to do. OTOH, it's a hard length to defend, based on my (non-elements) experience at RFPP. I'll dial it back and post a note on the talk page, but ultimately I won't be watching it, so feel free to change it back if it becomes necessary.

As far as "amount of vandalism" is concerned, here are my top indications that protection is needed (see also: WP:ROUGH):
 Extreme vandalism (compare to the daily featured article, but generally > 5 unique IPs in 24 hours, or 3-4 unique IPs per day over a slightly longer period)
 Sockpuppetry, if protecting the article is easier than an IP/rangeblock. (see Pioneer Courthouse Square for an extreme example of this)
 BLP. This one is obvious. Especially for
 Unsourced fancruft. Usually this is for articles that are continually getting edit-warred about the genre of a band, or the rumor that someone won the latest season of Survivor, or pretty much any article related to wrestling/MMA.
 The squishy stuff: if an article is super-stable (compare diffs to 'cur', no productive changes over last 100 edits or N months) and the IPs never have anything to contribute.
The last one is really the sticking point. In the recent history of Vanadium (just looking to the 20th or so), I see two repeat-offender IPs and a couple of random ones. The repeat-offenders should be warned and blocked for a short time if they haven't been blocked before. If it were (was) me, I'd feel comfortable semi-protecting the article for 3 days, *maybe* a week if I was frustrated.
Finally, generally the semi-protection ramps up in length. So a common pattern I use is 3 days, 2 weeks, 1 month, 3 months, 12 months, then indefinite. Each time it should come unprotected and show big problems with IPs.
As an aside, I didn't mean for this to be so long, and apologies if you know all of this. I tried to cast it as a personal opinion because it somewhat *is*. And I'm being so verbose because you are a new admin (congrats, of course), and I'm hoping it helps without coming off condescending.
Heh, that was a LOT of rambling. My apologies -)