Against the Elements.

Unclued lights are all elements from the periodic table.

Across:
1. (11)
9. Liver atrophy for Ida and sister (9)
10. Waterway hidden by American alcohol (5)
11. (6)
12. Edge oceanic none extracted from the pancreas (8)
13. Back home endlessly, wind from Angora goat (6)
15. (8)
18. Spoil me or tagetes (8)
19. Alcoholic expert with laid-back latitude (6)
21. SO4 plus bad aversion (8)
23. (6)
26. (5)
27. Northerly curve is South American flower (9)
28. NH3 reaction mislays moon badly (11)

Down:
1. (7)
2. Ran work in first (5)
3. Funding if back before poor canning (9)
4. Demolish artist from London area (4)
5. To pluck up courage I strip in disarray (8)
6. Large, married, backward killer (5)
7. (7)
8. Non-conservative anything at all dropped (8)
14. After house Hattersley keeps record, a study of time (8)
16. Spinal arch and Iliad confused (9)
17. (8)
18. Small horse required to stir nag (7)
20. Ancient string players using only half wrists now (7)
22. He turns girl reddish-brown (5)
24. Six special troops need border passes (5)
25. (4)