All the way back in 1869, Russian chemist Dmitri Mendeleev (1834-1907) created the framework for the modern periodic table. He sorted this table so that elements with like properties would be next to each other. Each column is its own group with contains like elements.
In this article, we will be looking at group 5A. We will learn the names of each element, their physical properties, their chemical properties, and what compounds that commonly form.
- This article covers the elements of group 5A.
- First, we will learn where group 5A is on the periodic table and see which elements are in this group.
- Next, we will look at the electron configuration for each element in this group.
- Then, we will learn about this group's valence electrons and how this effects these elements' oxidation states.
- After that, we will look at some trends in this group's properties.
- Lastly, we will look at some common compounds these elements will form.
Group 5A elements
Group 5A is the 15th column in the periodic table
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**
**While Moscovium is a group 5A element, we will not be discussing it in this lesson. Moscovium is an extremely radioactive man-made element. While its properties have been estimated based on calculations, they are not widely confirmed, which is why we will not be discussing this element.
Group 5A electron configuration
Group 5A elements follow a trend in their electron configuration.
Electron configuration tells us the distribution of electrons around a nucleus
Below is a table listing each element's electron configuration, where their valence electrons (outermost electrons) are highlighted in blue
| Element name | Electron configuration |
| Nitrogen (N) | 1s22s22p3 |
| Phosphorus (P) | 1s22s22p63s23p3 |
| Arsenic (As) | 1s22s22p63s23p63d104s24p3 |
| Antimony (Sb) | 1s22s22p63s23p63d104s24p64d105s25p3 |
| Bismuth (Bi) | 1s22s22p63s23p63d104s24p64d105s25p64f145d106s26p3 |
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.
An element's oxidation state tells us the number of electrons lost (+n) or gained (-n) during bonding
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.
In a double bond, the two elements share 4 electrons. However, in a triple bond, the elements share 6 electrons. For example, N2 has a triple bond between the two nitrogen atoms, since each nitrogen can donate 3 electrons.
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.
Rainbow bismuth
Bismuth can be easily oxidized when exposed to air. When bismuth reacts with oxygen, it forms an oxidation layer, which changes the bismuth's color. The thickness of the oxide layer varies, which causes different wavelengths of light to reflect off it, making the bismuth have a rainbow-like appearance
Fig.2-Bismuth has a rainbow appearance when oxidized
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.
Group 5A - Key takeaways
- Group 5A is the 15th column in the periodic table
- 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 elements have 5 valence electrons, with the general electron configuration of ns2np3
- The oxidation states for each element are:
- Nitrogen: any between -3 and 5
- Most common are -3, +3, and +5
- Phosphorus: 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
- When you go down the group, boiling point and atomic radius increases while electronegativity and ionization energy decreases
- Group 5A elements commonly react with hydrogen, oxygen, the halogens, and transition meals
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