These are represented by solid objects with connectors in molecular model kits. Hydrogen can form one bond. Oxygen is represented by a red object. Oxygen forms two bonds. Oxygen can form one double bond or two single bonds.
Carbon is represented by a black object.
Carbon forms four bonds. Chlorine is represented by a green object. Chlorine in organic compounds can form one bond. Life is not as simple in inorganic compounds but chlorine only forms single bonds. Nitrogen is represented by a blue object.