Across
1
Substance with pH below 7
3
Substance with pH above 7
5
Particle of light
6
Center of an atom or cell
7
Force that attracts objects together
8
Amplified beam of light
Down
2
Ball of burning gas in space
4
Mass per unit volume
5
Glass that splits light into spectrum
9
Chemical element in table salt
10
Unit of force
11
Blocking of light by a celestial body