Covalent Bonds

Single Covalent Bonds

Covalent compounds

• Covalent compounds are formed when electrons are shared between atoms
• Only non-metal elements participate in covalent bonding
• As in ionic bonding, each atom gains a full outer shell of electrons
• When two or more atoms are chemically bonded together, we describe them as ‘molecules’

Covalent bonding in non-metals

Hydrogen:

Chlorine:

H₂O:

CH₄ (methane):

NH₃ (ammonia):

HCl:

Ionic & Covalent Compounds

• Ionic compounds
  • Have high melting and boiling points so ionic compounds are usually solid at room temperature
  • Not volatile so they don’t evaporate easily
  • Usually water-soluble as both ionic compounds and water are polar
  • Conduct electricity in molten state or in solution as they have ions that can move and carry a charge
• Covalent compounds
  • Have low melting and boiling points so covalent compounds are usually liquids or gases at room temperature
  • Usually volatile which is why many covalent organic compounds have distinct aromas
  • Usually not water-soluble as covalent compounds tend to be nonpolar but can dissolve in organic solvents
  • Cannot conduct electricity as all electrons are involved in bonding so there are no free electrons or ions to carry the charge