Write the formula for calcium chloride. explain how you determined this formula

Calcium forms an ion with a positive 2 charge and chlorine forms an ion with a negative one charg, so the formula is CaCl2

Group 1 metals and group 2 metals form positive ions by losing 1 and 2 electrons respectively. Non-metals in group 17 gain 1, group 16 gain 2 and group 15 gain 3. Elements which lose electrons form positive ions while elements that gain electrons form negative ions. 

To write a formula, you must balance charges so the overall charge is zero. A simple way to do this is to swap the # of the ion's charge and make it the subscript of the other ion. However, leave off the number 1 and reduce to lowest whole number ratio.

atomic number of carbon is 6

electronic configuration of carbon is 1s²2s²2p²

orbital diagram of carbon is as shown here in the image.

colorless gas, exhibiting a blue glow when placed in an electric field

b) solid

its a type of rock