matching chemistry?

[stella]

word list:
atoms/ ions/ molecules, eight/ four, error, kernel/valence, metal/nonmental, O(oxygen), pairs, share/transfer

when atoms are held together by covalent bonds, a ... or a polyatomic... is formed. The electron -dot symbols for indivdual atoms can be used to construct dot diagrams for molecules and polyatomic.. . the symbol for each element represents the nucleus and ... electrons. when atoms form covalen bonds, each atoms must share enoght electrons to fill its ..shell witha t least a share in the total of ... electrons, that is, ... pairs of electrons.
Constructing dot diagrams beocme a trial and .. process until a reasonable structure is drawn. the following suggestions will help reduce the number of trials and errors.
a. choose a central atom, generally an ... other than H or O, which is bonded to not more than ... other atoms.
b. in ternary compoudns, H atoms are generally bonded to ...a toms.

i have no clue about this.....