# ABC graphs/Definitions

### Acronym and definitions

Letter Words Concept Notation Numerical value
A atom atom with bonding electrons symbol A
B bond bonding path or σ-binding pair line B
C charge residual charge characters (−,=,≡,+,⧺,ᚒ) C
D dot Non-σ-bonding electrons in pair(s) or as single(s) dots/dot D
E ellipse unoccupied orbital hyperellipse E

### Atoms and number of bonding electrons

Atom symbols are given in the periodic table of elements. Number of bonding electrons equals to the group number for s, sd and sf elements and to the last digit in the group number of sp elements. Let us denote that number as A.

To arrange the atoms one may follow the rules: [comment: to be written].

### Bonding paths and σ-bonds

Any bonds in the ABC-type graphs is drawn with a single line as it corresponds to a bonding path.

[Comment: add the definition of a bonding path and the difference from a σ-bond]

Let us denote the number of σ-bonds formed by a given atom as B.

### Residual charge

Residual charge on the most electronegative atoms is a charge left after creating 'N' σ-bonds with the corresponding anions, e.g. N3−, O2−, F−.

All other residual charges are calculated using the electroneutrality principle.

Let us denote the residual charge value of a given atom as C.

### Non-σ-bonding electrons

[Comment: there should be a better name. Obviously, these are not the typical lone electrons.]

Let us denote the number of non-σ-bonding electrons as D:

D = A − B − C

### Unoccupied orbitals

Let us denote the number of unoccupied orbitals associated with a given atom as E:

E = N − B − D· − D:

where N is the number of bonding orbitals of the atom (s,p,d,f), D· is a number of singles, D: is a number of pairs.