Do I have to implement a hash for my enum?

test.nim

import tables

type
  Element* {.pure.} = enum
    invalid    = (-1,  "Inv"),
    unknown    = (0, "*"),
    hydrogen   = (1, "H"),
    boron      = (5, "B"),
    carbon     = (6, "C"),
    nitrogen   = (7, "N"),
    oxygen     = (8, "O"),
    fluorine   = (9, "F"),

    phosphorus = (15, "P"),
    sulfur     = (16, "S"),
    chlorine   = (17, "Cl"),

    bromine    = (35, "Br"),
    iodine     = (53, "I")

let Valencies*: Table[Element, set[int8]] =
  {
    hydrogen: {1.int8},
    boron: {3.int8},
    carbon: {4.int8},
    nitrogen: {3.int8, 5},
    oxygen: {2.int8}
  }.toTable
  
#[ The error message:
type mismatch: got <Element>

but expected one of:
proc hash(x: char): Hash
proc hash(x: float): Hash
proc hash[A](aBuf: openArray[A]; sPos, ePos: int): Hash
proc hash(x: int64): Hash
proc hash[T: tuple](x: T): Hash
proc hash(sBuf: string; sPos, ePos: int): Hash
proc hash[T: proc](x: T): Hash
proc hash(x: int): Hash
proc hash[T: Ordinal](x: T): Hash
proc hash(x: cstring): Hash]#