Observed matter not measurable by current methods is called what?

Dark Matter

Explanation:

Observed matter not measurable by current methods is called Dark Matter.

This is a matter that represents 25% of the space.

They named it like that because this matter does not emit any electromagnetic energy, like a light.

It also not reacts with any electromagnetic energy.

Scientifics know it's existence because it does interact with the gravity from stars and galaxies.

ca has a crystalline lattice with positive ions (since it is a metal, metals are positively charged) and electrons flow freely in its structure since the ca atoms have a large nuclear radius so the electrons are not tightly held, therefore the electrons can flow freely since they are not being highly attracted by the nucleus. moreover, one of the properties of metals are that they are conductors of electricity, thus proving ca is the element.