---
id: kb-2026-00334
title: Periodic Table
schema_type: TechArticle
category: science
language: en
confidence: medium
last_verified: "2026-05-28"
created_date: "2026-05-22"
generation_method: ai_structured
ai_models:
  - claude-opus
derived_from_human_seed: true
conflict_of_interest: none_declared
is_live_document: false
data_period: static
atomic_facts:
  - id: af-science-periodic-table-1
    statement: >-
      IUPAC publishes an official periodic table and element resources for standard element names,
      symbols, and atomic-number ordering.
    source_title: Periodic Table of Elements
    source_url: https://iupac.org/what-we-do/periodic-table-of-elements/
    confidence: medium
  - id: af-science-periodic-table-2
    statement: >-
      Britannica states that Dmitri Mendeleev presented an early periodic table in 1869 by arranging
      elements according to recurring chemical properties.
    source_title: Periodic table
    source_url: https://www.britannica.com/science/periodic-table
    confidence: medium
  - id: af-science-periodic-table-3
    statement: >-
      IUPAC announced in 2016 that four new elements completed the seventh row of the periodic
      table.
    source_title: Four new elements complete the seventh row of the periodic table
    source_url: https://iupac.org/four-new-elements-complete-seventh-row/
    confidence: medium
completeness: 0.88
known_gaps:
  - >-
    Certain sub-topics are covered at a general level; specialized edge cases and nuanced
    applications may not be fully addressed
disputed_statements: []
primary_sources:
  - id: ps-science-periodic-table-1
    title: Periodic Table of Elements
    type: standard
    year: 2026
    institution: International Union of Pure and Applied Chemistry
    url: https://iupac.org/what-we-do/periodic-table-of-elements/
  - id: ps-science-periodic-table-2
    title: Periodic table
    type: encyclopedia
    year: 2026
    institution: Encyclopaedia Britannica
    url: https://www.britannica.com/science/periodic-table
  - id: ps-science-periodic-table-3
    title: Four new elements complete the seventh row of the periodic table
    type: standard
    year: 2016
    institution: International Union of Pure and Applied Chemistry
    url: https://iupac.org/four-new-elements-complete-seventh-row/
secondary_sources: []
updated: "2026-05-28"
---
## TL;DR
The periodic table organizes chemical elements by atomic number and recurring chemical behavior. It is both a practical reference for element names and symbols and a conceptual map of periodic trends.

## Core Explanation
The modern periodic table is ordered by atomic number, with columns grouping elements that often share related chemical behavior. Mendeleev's 1869 table was historically important because it organized known elements around recurring properties and left room for patterns to guide later discoveries. IUPAC maintains official element information and announced in 2016 that the addition of four elements completed the table's seventh row.

## Further Reading

- [IUPAC periodic table](https://iupac.org/what-we-do/periodic-table-of-elements/)
- [Britannica: periodic table](https://www.britannica.com/science/periodic-table)
- [IUPAC seventh-row announcement](https://iupac.org/four-new-elements-complete-seventh-row/)