NY Times Crossword
July 22, 2020
Peter A.Collins (adapted)

The phrases below each share the same unusual feature. Can you determine what it is?

1. MILITARY JARGON
2. ISN'T IT EXCITING?
3. SAFE ENVIRONMENT
4. THOREAU'S GOLDEN POND

HINT:
The clues all have the same chemistry.
(BIG) HINT:
Periodic Table

Answers:

Each clue contains the chemical symbol and name of an element:

1. militARy     jARGON 
2. iSN't it        exciTINing
3. saFE            envIRONment
4. thoreAU's   GOLDen pond*

*Thoreau live on Walden Pond. This is an intentional error (by me) for the sake of the puzzle's theme.