Period (periodic table) across periods. Seven periods of elements occur naturally on Earth. For period 8, which includes elements which may be synthesized after 2016, see the extended periodic table. A group in chemistry means a family of objects with similarities like different families. There are 7 periods, going horizontally across the periodic table. The first period contains the least elements than any other, with only two, hydrogen and helium. They therefore do not follow the octet rule. Chemically, helium behaves like a noble gas, and thus is taken to be part of the group 18 elements. However, in terms of its nuclear
The Periodic Table (Basher book) get people engaged is to make it accessible while still presenting hard facts and knowledge," while Basher was concerned that the book's design be "sharp and focused" in order to "connect with today's visually advanced young audience." "Publishers Weekly" said that the book was a "lively introduction to the chart that has been the bane of many a chemistry student", and in a review in "New Scientist", Vivienne Greig called "The Periodic Table" "an engrossing read and an ideal way to painlessly impart a great deal of science history to seen-it-all-before teenagers." A review on the Royal Society of Chemistry