Periodic Table: Provide Atomic Mass for queries containing the name or "periodic table"

[moollaza]

Queries for atomic elements by name, e.g. "Helium", "Lathanum" should show the atomic mass instead of repeating the full name.

Suggested on Duck.co here: https://duck.co/ideas/idea/6804/show-all-information-in-periodic-table-goodie

---

Also it looks like "periodic table" isn't a trigger for this IA and I think it should be added. Queries like https://duckduckgo.com/?q=periodic+table+he&t=ffab should also show the element name and mass.

We may need to update the design to always allow for the atomic mass /cc @abeyang

/cc @zblair

---

IA Page: http://duck.co/ia/view/periodic_table

[amitdev]

This looks easy - does the following format look good? If so, I can raise a PR.

[mintsoft]

@amitdev Looks cool

[amitdev]

Submitted PR #1973.