Theory:

A chemical compound is formed when two distinct elements are chemically combined i.e. chemical bonds form between their atoms.
Example:
shutterstock_1574046667.jpg
Salt \(NaCl\)
  
shutterstock_408620665.jpg
Water\(H_2O\)
  
Ozone \(O_3\), Nitrogen dioxide \(NO_2\), and so on.
Compounds are a form of matter created by combining two or more elements in a specific mass ratio. Chemical methods may be used to decompose it into its constituent components.
 
shutterstock_613449758.jpg
 
Properties of Compounds:
 
shutterstock_209116279.jpg
  • Two or more elements are chemically mixed in a compound. 
  • The elements in a compound are present in a fixed mass ratio.
  • Physical methods cannot isolate the constituents of a compound.
  • The constituents of a compound lose their identities, i.e., A compound's properties vary from those of its constituent elements.
Example:
Constituent elements in a compound:
 
Water (\(H_2O\)) has three atoms: Two hydrogen (H) atoms and one oxygen (O) atom.
 
shutterstock_209116279.jpg
 
Methane  \(CH_4\) with five atoms: One carbon (C) atom and four hydrogen (H) atoms.
 
Glucose  \(C_6H_{12}O_6\) contains elements of carbon \(6\), hydrogen \(12\) and oxygen \(6\) combined to form a glucose molecule.
 
shutterstock_1574046667.jpg
 
Sodium chloride \(NaCl\) contains the two elements: sodium and chlorine atoms combined to form a sodium chloride molecule.