<P> Because atoms and molecules are three - dimensional, it is difficult to use a single method to indicate orbitals and bonds . In molecular formulas the chemical bonds (binding orbitals) between atoms are indicated in different ways depending on the type of discussion . Sometimes, some details are neglected . For example, in organic chemistry one is sometimes concerned only with the functional group of the molecule . Thus, the molecular formula of ethanol may be written in conformational form, three - dimensional form, full two - dimensional form (indicating every bond with no three - dimensional directions), compressed two - dimensional form (CH--CH--OH), by separating the functional group from another part of the molecule (C H OH), or by its atomic constituents (C H O), according to what is discussed . Sometimes, even the non-bonding valence shell electrons (with the two - dimensional approximate directions) are marked, e.g. for elemental carbon C. Some chemists may also mark the respective orbitals, e.g. the hypothetical ethene anion (C = C) indicating the possibility of bond formation . </P> <Table> <Tr> <Td> </Td> <Td> This section needs additional citations to secondary or tertiary sources such as review articles, monographs, or textbooks . Please add such references to provide context and establish the relevance of any primary research articles cited . Unsourced material may be challenged and removed . (March 2015) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This section needs additional citations to secondary or tertiary sources such as review articles, monographs, or textbooks . Please add such references to provide context and establish the relevance of any primary research articles cited . Unsourced material may be challenged and removed . (March 2015) </Td> </Tr> <Table> <Tr> <Td_colspan="3"> Typical bond lengths in pm and bond energies in kJ / mol . Bond lengths can be converted to Å by division by 100 (1 Å = 100 pm). Data taken from University of Waterloo . </Td> </Tr> <Tr> <Th> Bond </Th> <Th> Length (pm) </Th> <Th> Energy (kJ / mol) </Th> </Tr> <Tr> <Th_colspan="3"> H--Hydrogen </Th> </Tr> <Tr> <Td> H--H </Td> <Td> 74 </Td> <Td> 436 </Td> </Tr> <Tr> <Td> H--O </Td> <Td> 96 </Td> <Td> 366 </Td> </Tr> <Tr> <Td> H--F </Td> <Td> 92 </Td> <Td> 568 </Td> </Tr> <Tr> <Td> H--Cl </Td> <Td> 127 </Td> <Td> 432 </Td> </Tr> <Tr> <Th_colspan="3"> C--Carbon </Th> </Tr> <Tr> <Td> C--H </Td> <Td> 109 </Td> <Td> 413 </Td> </Tr> <Tr> <Td> C--C </Td> <Td> 154 </Td> <Td> 348 </Td> </Tr> <Tr> <Td> C--C = </Td> <Td> 151 </Td> <Td> </Td> </Tr> <Tr> <Td> = C--C ≡ </Td> <Td> 147 </Td> <Td> </Td> </Tr> <Tr> <Td> = C--C = </Td> <Td> 148 </Td> <Td> </Td> </Tr> <Tr> <Td> C = C </Td> <Td> 134 </Td> <Td> 614 </Td> </Tr> <Tr> <Td> C ≡ C </Td> <Td> 120 </Td> <Td> 839 </Td> </Tr> <Tr> <Td> C--N </Td> <Td> 147 </Td> <Td> 308 </Td> </Tr> <Tr> <Td> C--O </Td> <Td> 143 </Td> <Td> 360 </Td> </Tr> <Tr> <Td> C--F </Td> <Td> 134 </Td> <Td> 488 </Td> </Tr> <Tr> <Td> C--Cl </Td> <Td> 177 </Td> <Td> 330 </Td> </Tr> <Tr> <Th_colspan="3"> N--Nitrogen </Th> </Tr> <Tr> <Td> N--H </Td> <Td> 101 </Td> <Td> 391 </Td> </Tr> <Tr> <Td> N--N </Td> <Td> 145 </Td> <Td> 170 </Td> </Tr> <Tr> <Td> N ≡ N </Td> <Td> 110 </Td> <Td> 945 </Td> </Tr> <Tr> <Th_colspan="3"> O--Oxygen </Th> </Tr> <Tr> <Td> O--O </Td> <Td> 148 </Td> <Td> 145 </Td> </Tr> <Tr> <Td> O =O </Td> <Td> 121 </Td> <Td> 498 </Td> </Tr> <Tr> <Th_colspan="3"> F, Cl, Br, I--Halogens </Th> </Tr> <Tr> <Td> F--F </Td> <Td> 142 </Td> <Td> 158 </Td> </Tr> <Tr> <Td> Cl--Cl </Td> <Td> 199 </Td> <Td> 243 </Td> </Tr> <Tr> <Td> Br--H </Td> <Td> 141 </Td> <Td> 366 </Td> </Tr> <Tr> <Td> Br--Br </Td> <Td> 228 </Td> <Td> 193 </Td> </Tr> <Tr> <Td> I--H </Td> <Td> 161 </Td> <Td> 298 </Td> </Tr> <Tr> <Td> I--I </Td> <Td> 267 </Td> <Td> 151 </Td> </Tr> </Table>

What are the 3 types of chemical bond