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Research draft

chromium

vr.tr.chromium · PHY.MAT

Let an agent identify chromium and its properties, relay production, uses, isotopes and health effects from reference sources, distinguish trivalent from hexavalent chromium, and route exposure questions to occupational health authorities.

Thing Registry Physical world and living systems

Research draft, second pass

A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.

written by Claude from model knowledge without web access - no source was read, every claim is a lead to verify

Researched by: Claude

Purpose and description

Let an agent identify chromium and its properties, relay production, uses, isotopes and health effects from reference sources, distinguish trivalent from hexavalent chromium, and route exposure questions to occupational health authorities.

A chemical element with symbol Cr and atomic number 24, a hard, lustrous, corrosion-resistant transition metal obtained from chromite ore, used above all in stainless steel and other alloys, in chrome plating, pigments, leather tanning and refractories; trivalent chromium is an essential trace element in small amounts, hexavalent chromium compounds are toxic and carcinogenic, and chromium is a common contact allergen, with four stable isotopes and radioactive ones from chromium-42 upward.

What it is for: Stainless steel, plating, pigments and tanning.

It can be relay properties and isotopes; explain production and uses; distinguish oxidation states and health effects; route exposure questions.

Distinguishing features

Corrosion resistance

Stainless steel component

Toxic hexavalent state

Contact allergen

What it looks like

A silvery, hard, bright metal that takes a high polish.

Physical character

atomic number: 24 Z

standard atomic weight: 51.996 u

melting point: 1907 degrees C

Mohs hardness: 8.5 scale

How it is recognised

Element 24, symbol Cr

Metal of stainless steel and chrome plating

Vanadium and manganese are the neighbouring elements

Related models

is a kind of - in registry terms

heavy metal

is a kind of - in registry terms

allergen

is a kind of - in registry terms

simple substance

is used in - the main application

stainless steel

In practice

Families and kinds

chromium metal and ferrochrome

trivalent chromium compounds

hexavalent chromium compounds such as chromates

chromium pigments such as chrome yellow and chromium oxide green

stable isotopes 50, 52, 53 and 54 and radioactive isotopes such as chromium-51

Identifiers

symbol Cr

CAS 7440-47-3

Standards and regulation

Occupational exposure limits for hexavalent chromium

REACH restrictions on chromium VI in leather and articles

Drinking water standards

RoHS limits in electronics

Failure modes and hazards

Hexavalent chromium toxicity and cancer

Contact dermatitis from chromium in cement and leather

Groundwater contamination

Confusing oxidation states

Also called

chromium-53chromium-42chromium-43chromium-44chromium-45chromium-46chromium-47chromium-48chromium-49chromium-55chromium-56chromium-57chromium-58chromium-59chromium-60chromium-61chromium-62chromium-63chromium-64chromium-65chromium-66chromium-67chromium-45mchromium-59mchromium-51chromium-54chromium-50hexavalent chromiumchromium cr-48chromium (native)chromium-52chromium-68chromium-69chromium-70(⁵⁴Cr)Chromium(⁴⁹Cr)Chromium

Where this came from

wikidata · CC0 1.0

Also registered as vr.tr.chromium

Drafted structure

Bundle to layer to finding to question, as the second pass will find it: 4 bundles · 8 layers · 8 findings · 16 questions.

Identify What chromium is.

Identity.

Properties

Properties.

Properties

Properties.

  1. What are the physical and chemical properties of chromium? definition
  2. Is the question about the metal, a trivalent compound or a hexavalent compound? boundary

Isotopes

Isotopes.

Isotopes

Isotopes.

  1. Which isotopes exist, and how is chromium-51 used in medicine? definition
  2. Which entry fits the specific isotope? action
Source Production and supply.

Supply.

Production

Production.

Production

Production.

  1. How is chromium produced from chromite as ferrochrome and metal? provenance
  2. Which entry fits chromite? action

Supply

Supply.

Supply

Supply.

  1. Who produces chromium, and how is it traded, with sources? measurement
  2. Which sources are cited? provenance
Use Uses and health.

Application.

Uses

Uses.

Uses

Uses.

  1. How is chromium used in steel, plating, pigments, tanning and refractories? provenance
  2. Which references are standard? provenance

Health

Health and environment.

Health

Health.

  1. What are the health effects of trivalent and hexavalent chromium, and what limits apply, in general terms? provenance
  2. Is the user asking about personal exposure, which needs occupational health or medical advice? boundary
Context History and cases.

Context.

Discovery

Discovery.

Discovery

Discovery.

  1. How was chromium discovered by Vauquelin in 1797 and named for its coloured compounds? provenance
  2. Which entry fits the history of chemistry? action

Cases

Contamination cases.

Cases

Cases.

  1. What notable hexavalent chromium contamination cases have been documented, as reported? provenance
  2. Which entry fits the specific case? action

What the second pass must settle

  • Should hexavalent chromium be a separate primary entry?
  • How should exposure limits be linked?
  • The registry entry has merged aliases naming isotopes; should they be split off?