Across
1
Particle of light
4
Molten rock beneath Earth surface
5
Center of an atom or cell
6
Magnetic metallic element
7
Unit of power
10
Naturally occurring inorganic solid
11
Reddish electrical conductor
Down
2
Gas essential for breathing
3
Unit of force
4
Measure of matter in an object
8
Nerve cell in the brain
9
Path of a planet around the sun