just check this. just see a element, for you to understand.

Define 'Mod'. For lua scripting, I suggest looking up some elements on the lua scripting forum and working around that.
For C++ mods, ie compiled mods, you need to know C++. That's slightly harder than lua, but lets you put the elements into an executable file like regular TPT.

enabled:is this disappears, or not.
menuvisible:are visible in menu or not.
menusection:which menu goes along.
Advection:how much the velocity of the air changes the velocity to the element.
AirDrag:Advection, flipped.
AirLoss:how much the element blocks VELOCITY of the air.
Collision:how much the element generates pressure when it collides a another element.
Diffusion:how fast the element "deform"s.
Explosive:Explodes by fire if 1, and with pressure if 2.
Falldown:how the element pool up. 0 for solid/gas/energy, 1 for powder, 2 for liquid.
Hardness:how resistant to ACID the element is.
Hotair:is/how fast the element generates a pressure/vaccum.
Gravity:how fast the element falls.
Meltable: melts when heat simulation is off, when more than 1.
Weight:how this element passes through other elements. (more weight, more surpassing)
Temperature: what temperature the element spawns.
State: what is the form. st_none:energy, st_solid:solid, st_liquid:liquid, st:gas:gas.
there is some of it that are not explained here. it is because it is self-explanatory.

@Lockheedmartin (View Post)

Don't forget Lua Modding 

@KissMyPixel

Lua script mod is a good way to start of.