Periodic-table element lookup API

Resolve a chemical symbol, element name, or atomic number to authoritative periodic-table data: group, period, block, category, standard atomic mass, electron configuration, and phase at STP — full 118-element coverage. Answers 'what is the atomic mass of iron', 'electron configuration of gold', 'what group is chlorine in', 'element with atomic number 79'.

Price$0.01per request

MethodPOST

Route/v1/ref/element

StatusLive

MIME typeapplication/json

Rate limit60/minute

CacheNo cache

refelementperiodic-tablechemistryatomicatomic-numberchemicalscience

API URLhttps://x402.hexl.dev/v1/ref/element

Integration docs

Example request

{
  "query": "Fe"
}

Example response

{
  "query": "Fe",
  "found": true,
  "atomicNumber": 26,
  "symbol": "Fe",
  "name": "Iron",
  "atomicMass": 55.845,
  "group": 8,
  "period": 4,
  "block": "d",
  "category": "transition metal",
  "phaseAtSTP": "solid",
  "electronConfiguration": "[Ar] 3d6 4s2"
}

Input schema

{
  "type": "object",
  "required": [
    "query"
  ],
  "properties": {
    "query": {
      "type": [
        "string",
        "number"
      ],
      "examples": [
        "Fe",
        "Gold",
        79
      ]
    }
  }
}

Output schema

{
  "type": "object",
  "additionalProperties": true
}