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A topic from the subject of Nomenclature in Chemistry.

  • 1 year ago
  • 6 min read

Nomenclature of Periodic Table Groups

The periodic table groups (vertical columns) are organized by the number of valence electrons, which largely determines the chemical properties of elements within a group. There are two main systems for naming these groups:

1. IUPAC Group Numbers (1-18):

The International Union of Pure and Applied Chemistry (IUPAC) recommends a simple numerical system. Groups are numbered consecutively from 1 to 18, starting from the leftmost column (alkali metals) and going to the rightmost column (noble gases).

  • Group 1: Alkali metals (Li, Na, K, etc.)
  • Group 2: Alkaline earth metals (Be, Mg, Ca, etc.)
  • Group 13: Boron group (B, Al, Ga, etc.)
  • Group 14: Carbon group (C, Si, Ge, etc.)
  • Group 15: Pnictogens (N, P, As, etc.)
  • Group 16: Chalcogens (O, S, Se, etc.)
  • Group 17: Halogens (F, Cl, Br, etc.)
  • Group 18: Noble gases (He, Ne, Ar, etc.)

This system is widely adopted and considered the standard.

2. CAS/American Group Numbers (IA-VIIIA):

This older system uses Roman numerals and letters (IA, IIA, IIIA, etc., up to VIIIA). This system is less common now but might still be encountered in older texts. It sometimes separates the transition metals into subgroups (B groups).

  • IA: Alkali metals
  • IIA: Alkaline earth metals
  • IIIA: Boron group
  • IVA: Carbon group
  • VA: Pnictogens
  • VIA: Chalcogens
  • VIIA: Halogens
  • VIIIA: Noble gases

Note: The transition metals and inner transition metals (lanthanides and actinides) are not typically included in a simple A/B group designation in this system.

Summary:

While both systems describe the same groups, the IUPAC system (1-18) is the preferred and universally accepted method for naming periodic table groups.

Nomenclature of Periodic Table Groups
Key Points:
  • Periodic table groups (also known as families) are vertical columns of elements that share similar chemical properties.
  • Groups are numbered 1-18 from left to right. The older Roman numeral system (I-VIIIA and VIIIB) is also sometimes used, though less common now.
  • Groups can be broadly classified into several categories based on properties. These categories aren't strictly defined and some elements may exhibit properties of multiple categories.
  • These categories include:
    1. Metals (primarily groups 1-12, with some transition metals extending further)
    2. Nonmetals (primarily groups 14-17, with some extending into group 13)
    3. Metalloids (elements exhibiting properties of both metals and nonmetals; a diagonal band spanning parts of groups 13-16)
    4. Noble gases (group 18)
  • The nomenclature of periodic table groups is based on their chemical reactivity and electronic configuration, leading to characteristic properties within each group.
Main Concepts: Group Names and Properties
  1. Group 1: Alkali metals - highly reactive metals that readily lose one electron to form +1 ions. They react vigorously with water to form strong alkaline (basic) solutions.
  2. Group 2: Alkaline earth metals - reactive metals that readily lose two electrons to form +2 ions. They react with water, though generally less vigorously than alkali metals, to form alkaline solutions.
  3. Group 13: Boron group - This group contains metalloids and metals. Their properties vary significantly.
  4. Group 14: Carbon group - This group contains nonmetals, metalloids, and metals. Carbon is the basis of organic chemistry. The properties vary greatly across the group.
  5. Group 15: Nitrogen group (Pnictogens) - This group contains nonmetals, metalloids, and metals. Nitrogen is essential for life. The properties vary across the group.
  6. Group 16: Oxygen group (Chalcogens) - This group contains nonmetals and metalloids. Oxygen is essential for life and highly reactive. The properties vary across the group.
  7. Group 17: Halogens - highly reactive nonmetals that readily gain one electron to form -1 ions. They form strong acids with hydrogen.
  8. Group 18: Noble gases - extremely unreactive gases that exist as monatomic elements due to their stable electron configurations.
Experiment: Nomenclature of Periodic Table Groups
Materials:
  • Periodic table
  • Markers
  • Paper
Procedure:
  1. Observe the periodic table and identify the different vertical columns, called groups.
  2. Label each group with its corresponding group number (1-18) using a marker.
  3. For groups 1-2 and 13-18, write the group name below the group number. Examples include:
    • Group 1 - Alkali Metals
    • Group 2 - Alkaline Earth Metals
    • Group 13 - Boron Family
    • Group 14 - Carbon Family
    • Group 15 - Pnictogens (or Nitrogen Family)
    • Group 16 - Chalcogens (or Oxygen Family)
    • Group 17 - Halogens
    • Group 18 - Noble Gases
  4. Note that Groups 3-12 are the transition metals and are generally not given a family name.
Key Procedures:
  • Identify the vertical columns in the periodic table as groups.
  • Assign the corresponding group numbers (1-18) to each group.
  • Utilize the group numbers and family names (where applicable) to name the groups.
Significance:
  • Provides a systematic organization for elements based on their chemical properties.
  • Helps predict the reactivity and behavior of elements within the same group.
  • Facilitates the understanding of periodic trends and relationships among elements.

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