Across
1
Chemical element in table salt
2
Amplified beam of light
4
Magnetic metallic element
5
Substance with pH above 7
8
Center of an atom or cell
10
Force that attracts objects together
Down
2
Curved glass that refracts light
3
Infectious microscopic agent
6
Group of similar cells
7
Blocking of light by a celestial body
9
Unit of energy