Write Lewis structures for the following molecules or ions, which have central atoms that do not obey the octet rule:
Br3 -
BH3
CIE5
PF5
XeF6

Explain which group an element with the electron configuration 1s2 2s2 2p6 3s2 3p6 3d1 4s2 belongs to.

To find the enthalpy of a reaction in the lab, you measured the of the reactants and the change during the reaction.

Select the correct answer from each drop-down menu. to make a table of the elements, dmitri mendeleev sorted the elements according to their . he then split the list of elements into several columns so that elements beside each other had similar .