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Anomalous Behaviour of Beryllium

Anomalous Behaviour of Beryllium

Shivani PooniaUpdated on 02 Jul 2025, 06:04 PM IST

Imagine certain situations whereby you need your material strong, yet light, corrosive-resistant, and resistant to high temperatures. Obviously, at no time is such material coming at a free cost into being. This material, beryllium, very vital in the engineering industry, like aerospace, where every gram counts, and the electronics industry because it deals with durability. Although beryllium, due to its position within Group 2 of the Periodic Table, is an alkaline earth metal by definition, some of its properties may differ appreciably from those of other family members in the same column, that is, magnesium and calcium. Deviation from this type of behavior is called anomalous behavior.

This Story also Contains

  1. Properties of Beryllium
  2. Understanding the Anomalous Behavior of Beryllium
  3. Some Solved Examples
Anomalous Behaviour of Beryllium
Anomalous Behaviour of Beryllium

Berylium differs from the rest of the alkaline earth metals on account of its small atomic size, high electronegativity, and a slight difference in electronic configuration. Be2+ is very small. It exerts a high polarising effect on any anion associated with it. On account of this, beryllium compounds show a covalent character. Its compounds have low melting points and are soluble in organic solvents. These are hydrolyzed in water.

Properties of Beryllium

  • It is the hardest of all alkaline earth metals.
  • The melting and boiling points of the beryllium are the highest.
  • It is not affected by the atmosphere.
  • It does not decompose water.
  • It has the tendency to form covalent compounds
  • It does not react directly with hydrogen.
  • It dissolves in alkalies with the evolution of hydrogen.
  • It does not liberate hydrogen from acids readily.
  • Its oxide is amphoteric in nature.
  • Its hydroxide is amphoteric in nature.
  • Its carbide on hydrolysis evolves methane.
  • Its carbonate is not stable towards heat.
  • Its sulphate is soluble in water.
  • BeCl2 is a covalent compound.
  • It has a strong tendency to form complex compounds.
  • It has a tendency to form alloys.

Commonly Asked Questions

Q: How does the size of beryllium compare to other elements in its group?
A:
Beryllium is significantly smaller than other elements in its group. This is due to its low atomic number and high effective nuclear charge, which pulls the electrons closer to the nucleus, resulting in a smaller atomic radius.
Q: What is the impact of beryllium's small size on its chemical properties?
A:
Beryllium's small size leads to a high charge density, which results in a strong polarizing effect on nearby ions or molecules. This causes beryllium to form covalent bonds rather than ionic bonds, unlike other alkaline earth metals.
Q: How does beryllium's electronegativity compare to other alkaline earth metals?
A:
Beryllium has a higher electronegativity than other alkaline earth metals. This is due to its smaller size and higher effective nuclear charge, which allows it to attract electrons more strongly in chemical bonds.
Q: What is the oxidation state of beryllium in its compounds?
A:
Beryllium typically has an oxidation state of +2 in its compounds, like other alkaline earth metals. However, due to its covalent nature, the charge is often not a full +2 but is shared between beryllium and the other elements in the compound.
Q: How does beryllium's melting point compare to other group 2 elements?
A:
Beryllium has a much higher melting point compared to other group 2 elements. This is due to the strong covalent bonding in its solid state, which requires more energy to break than the metallic bonding in other alkaline earth metals.

Understanding the Anomalous Behavior of Beryllium


Beryllium, atomic number 4, is a member of the periodic table Group 2: the alkaline earth metals. Be, though belonging to this group in the Periodic Table, shows most of its properties to be very different from its congeners: magnesium, calcium, strontium, Ba, and radium, Ra.

The deviation arises due to:

  • Relatively High Electronegativity
  • Small atomic and ionic size
  • High Ionization Energy
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Characteristics and Examples of Anomalous Behavior of Beryllium


The bond cannot be ionic with equal sharing of electrons because it is impossible for beryllium due to its small size and high charge of. This turns out to be another striking feature of its anomalous behavior. While MgCl2 and CaCl2 can be the usual examples of ionic compounds, beryllium chloride itself is actually a covalent polymer. The covalency extends to its compounds with other elements too. Even the hydride of beryllium consists of structures that are polymeric rather than just mere simple ionic compounds.

The following are some of the key examples:

Beryllium Chloride, BeCl2: The chloride is a covalent polymeric structure rather than being an example of a simple ionic compound.

Beryllium Hydride, BeH2: The hydride also forms polymeric structures.

Beryllium Oxide, BeO: The oxide is amphoteric, and dissolves both in acids and bases to give beryllium salts and beryllates, respectively.

Importance and Uses in Various Fields of the Anomalous Property of Beryllium


Such anomalous behavior of beryllium plays a vital role both in academics and practical applications.

  • This anomalous behavior of beryllium helps the academic chemist about how atomic size and ionization energy in atoms affect chemical bonding.
  • Nuclear Reactors Used as neutron moderator and reflector.
  • Draws the attention of the aerospace industry for aircraft and spacecraft parts since it is a light metal with high strength, and hence is an ideal metal to be used for their construction.

Recommended topic video on ( Anomalous Behaviour of Beryllium)

Some Solved Examples

Example 1: A metal M readily forms a soluble sulfate MSO₄ and has an oxide MO that becomes inert on heating. It also forms an insoluble hydroxide M(OH)₂ that is soluble in NaOH. What is the identity of metal M?

1) Be

2) Mg

3) B

4) Ar

Solution: The metal is Beryllium (Be). It forms BeSO₄, which is water-soluble, and its oxide BeO becomes inert upon heating.

Example 2: Which metal is used for making X-ray tube windows due to its transparency to X-rays?

1) Mg

2) Ne

3)Be

4) Na

Solution:The metal used is Beryllium (Be), as it is transparent to X-rays.

Example 3: How many atmospheric compounds are present among the following: BeO, BaO, Be(OH)₂, Sr(OH)₂?

1) 3

2) 4

3) 2

4) 1

Solution:There are 2 atmospheric compounds: BeO and Be(OH)₂. Both are amphoteric, unlike the other compounds listed.

Summary
Anomalous behavior like this aside, the general path of beryllium would be quite different from that of the other alkaline earth metals. It is these very small atomic size, high ionization energy, and peculiar bonding properties that come together to act in unison to give out the described unique properties. Beryllium varies a lot from the members of that group since it has apparently a different trend about resistance formation to the formation of the ionic bond, and also it has amphoteric oxides and hydroxides with high covalency in compounds

Frequently Asked Questions (FAQs)

Q: How does the lattice energy of beryllium compounds compare to those of other alkaline earth metals?
A:
Beryllium compounds generally have higher lattice energies compared to similar compounds of other alkaline earth metals. This is due to beryllium's small size and high charge density, which lead to stronger electrostatic interactions in the crystal lattice.
Q: How does the electron affinity of beryllium compare to other group 2 elements?
A:
Beryllium has a lower electron affinity compared to other group 2 elements. This is because its 2s orbital is fully filled, making it less favorable to accept an additional electron. This contributes to beryllium's tendency to form covalent rather than ionic bonds.
Q: How does the crystal structure of metallic beryllium differ from other alkaline earth metals?
A:
Metallic beryllium has a hexagonal close-packed (hcp) crystal structure, while other alkaline earth metals typically have body-centered cubic (bcc) or face-centered cubic (fcc) structures. This difference is due to beryllium's smaller size and stronger covalent character.
Q: How does beryllium's first ionization energy compare to other group 2 elements?
A:
Beryllium has a significantly higher first ionization energy compared to other group 2 elements. This is due to its small size and the stability of its fully filled 2s orbital, making it more difficult to remove an electron.
Q: How does the solubility of beryllium salts compare to other group 2 element salts?
A:
Beryllium salts are generally less soluble than those of other group 2 elements. This is due to the covalent nature of beryllium compounds and the strong lattice energy in its solid structures.
Q: Why is beryllium carbide (Be2C) different from other alkaline earth metal carbides?
A:
Beryllium carbide (Be2C) is different because it has a covalent structure, unlike the ionic carbides formed by other alkaline earth metals. When hydrolyzed, it produces methane instead of acetylene, which is typical for ionic carbides.
Q: How does the thermal stability of beryllium compounds compare to those of other group 2 elements?
A:
Beryllium compounds often have higher thermal stability compared to similar compounds of other group 2 elements. This is due to the stronger covalent bonding in beryllium compounds, which requires more energy to break.
Q: Why does beryllium not form a stable nitrate like other alkaline earth metals?
A:
Beryllium does not form a stable nitrate because its small size and high charge density lead to extensive hydrolysis in aqueous solutions. Instead of forming a stable nitrate, beryllium tends to form complex hydroxyl species in water.
Q: How does beryllium's hydration energy compare to other group 2 elements?
A:
Beryllium has a much higher hydration energy compared to other group 2 elements. This is due to its small size and high charge density, which allows it to attract water molecules more strongly, forming strong hydration shells.
Q: What is the hybridization of beryllium in its compounds?
A:
Beryllium typically exhibits sp3 hybridization in its compounds. This allows it to form four covalent bonds, often resulting in tetrahedral geometry around the beryllium atom.
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