Group 5A

Group 5A elements

Since this group is also the 15th column, it is also called group 15. In addition, these elements are sometimes called pnictogens. The word comes from the ancient Greek word "pnigein", meaning "to choke" since breathing pure Nitrogen gas (the first element of this group) can cause you to choke. Talk about a dark nickname!

Below is where you can find these elements on the periodic table:

Fig.1-Where to find group 5A on the periodic table

The group is called "5A" since it is the 5th column across when you ignore the transition metals.

The elements in this group are:

• Nitrogen (N)- Element 7
• Phosphorus (P)- Element 15
• Arsenic (As)- Element 33
• Antimony (Sb)- Element 51
• Bismuth (Bi)- Element 83
• Moscovium (Mc)- Element 115**

Group 5A electron configuration

Group 5A elements follow a trend in their electron configuration.

Below is a table listing each element's electron configuration, where their Valence Electrons (outermost electrons) are highlighted in blue

Group 5A valence electrons

As you can see from their electron configurations, group 5A elements have 5 valence electrons.

Because of this, they have several possible oxidation states.

Let's break this down element by element:

• Nitrogen
  • Can have any oxidation state between -3 and 5
  • Most common are -3 (gain 3 electrons to have a full set of valence electrons), +3 (can lose all valence p-electrons), +5 (can lose set of valence electrons to have a new, full set of lower energy valence electrons)
• Phosphorus
  • Can have any oxidation state between -3 and 5
  • Most common are -3, +3, and +5
• Arsenic
  • Can have -3, +3, and +5 oxidation states
• Antimony
  • Can have -3, +3, and +5 oxidation states
• Bismuth
  • Can have -3, +3, and +5 oxidation states

For the lighter group 5A elements (nitrogen, phosphorus, and arsenic) the -3 oxidation state is more common, however, for the heavier elements (antimony and bismuth), the +3 oxidation state is more common.

For heavier elements, it is easier to lose electrons than to gain them. This is because the outermost electrons are farther away from the nucleus, so it doesn't have as much "pull" on them.

Because of these oxidation states, these elements are also able to form stable double and triple bonds.

Group 5A elements properties

The physical properties tend to vary across the group since it contains all three types of elements (non-metal, metalloid, and metal). For example, at room temperature, nitrogen is a nonmetal and colorless gas, while bismuth is a metal and a silver-pink solid.

Because of this, when we look at their properties, we often refer to the trends in properties.

Let's look at a few of these trends

• Boiling point:
  • The boiling point tends to increase as you go down the group. However, bismuth's boiling point (1,564 °C) is slightly less than antimony's (1,587 °C).
• Atomic radius (distance between center of nucleus and outermost electron(s)):
  • Increases as you go down the group.
• Electronegativity (tendency to attract/gain an electron):
  • Decreases as you go down the group.
• Ionization energy (energy it takes to remove one electron):
  • Decreases as you go down the group.

Group 5A compounds

Group 5A tends to form certain types of compounds due to their unique reactivity. Here are some examples:

• Hydrides
  • Group 5A elements can react with hydrogen to form pnictogen hydrides. There are two common forms depending on which element is being reacted
    • PnH₃-All pnictogens (Pn) can form trihydrides
    • LPn₂H₃-The light pnictogens (nitrogen, phosphorus, and arsenic) can form dipnictogens tetrahydrides, where LPn is a light pnictogen
• Oxides
  • Group 5A elements can react with oxygen to form oxides. There are several possible formulas for these oxides, which are dependent on the element/the element's common oxidation states
    • Nitrogen: NO, N₂O, N₂O₃, N₂O₄, and N₂O₅
    • Phosphorus: P₄O₆ and P₄O₁₀
    • Arsenic: As₂O₃, As₂O₅, and As₄O₆
    • Antimony: Sb₂O₃ and Sb₂O₅
    • Bismuth: Bi₂O₃ and Bi₂O₅
• Halides
  • Group 5A elements can react with group 17 elements (called the Halogens) to form halide compounds. These halide compounds come in two main forms:
    • PnX₃ and PnX₅-Where Pn is a pnictogen and X is a halide
      • Nitrogen is the exception, since it doesn't form NX₅
• Transition metals
  • Group 5A elements can form many different transition metal complexes.