Across
1
Second lightest element
5
The Red Planet
6
Positive particle in nucleus
8
Biological catalyst
9
Measure of matter in an object
10
Substance with pH above 7
11
Precious yellow metallic element
Down
2
Substance with pH below 7
3
Blocking of light by a celestial body
4
Chemical element in table salt
7
Disturbance that transfers energy