Across
1
Center of an atom or cell
3
Substance with pH below 7
5
Force that attracts objects together
9
Blocking of light by a celestial body
11
Curved glass that refracts light
Down
2
Infectious microscopic agent
4
Solid with repeating atomic pattern
6
Basic unit of life
7
Glass that splits light into spectrum
8
Ball of burning gas in space
10
Tissue that contracts for movement