To answer the question about arranging compounds in increasing coralency, we first need to clarify what is meant by "coralency." Although it's not a standard term in chemistry, it seems like a typo for "covalency." Covalency refers to the number of covalent bonds that an atom forms with other atoms. Let's consider the covalent bonding in each compound:
1. BeCl₂ (Beryllium dichloride):
- Beryllium (Be) has 2 valence electrons.
- Beryllium forms two single covalent bonds with two chlorine (Cl) atoms.
- Thus, BeCl₂ has a covalency of 2.
2. BCl₃ (Boron trichloride):
- Boron (B) has 3 valence electrons.
- Boron forms three single covalent bonds with three chlorine (Cl) atoms.
- Thus, BCl₃ has a covalency of 3.
3. AlCl₃ (Aluminum trichloride):
- Aluminum (Al) has 3 valence electrons.
- Aluminum forms three single covalent bonds with three chlorine (Cl) atoms.
- In addition to these three covalent bonds, Aluminum Chloride (AlCl₃) has a tendency to form a dimer (Al₂Cl₆), wherein each aluminum atom can form additional coordinate bonds, effectively increasing its bonding capability.
Given the above information, we can arrange the compounds in order of increasing covalency (number of covalent bonds per central atom):
1. BeCl₂: Beryllium forms 2 covalent bonds.
2. BCl₃: Boron forms 3 covalent bonds.
3. AlCl₃: Although aluminum forms 3 covalent bonds, it can also form additional coordinate bonds in its dimeric form, giving it an effective covalency that can be considered higher than BCl₃.
Thus, the order of increasing covalency is:
[tex]\[ \text{BeCl}_2 \ <\ \text{BCl}_3 \ <\ \text{AlCl}_3 \][/tex]
