<Table> <Tr> <Td> Primordial </Td> <Td> </Td> <Td> From decay </Td> <Td> </Td> <Td> Synthetic </Td> <Td> Border shows natural occurrence of the element </Td> </Tr> </Table> <Tr> <Td> Primordial </Td> <Td> </Td> <Td> From decay </Td> <Td> </Td> <Td> Synthetic </Td> <Td> Border shows natural occurrence of the element </Td> </Tr> <P> The s - block is on the left side of the periodic table and includes elements from the first two columns, the alkali metals (group 1) and alkaline earth metals (group 2), plus helium . Helium is a controversial element for the scientists as it can be placed in the second group of s block as well as the 18th group of p - block, but most scientists consider it to rest at the top of group 18 i.e. above neon (atomic number 10) as it has many properties similar to the group 18 elements . </P> <P> Most s - block elements are highly reactive metals due to the ease with which their outer s - orbital electrons interact to form compounds . The first period elements in this block, however, are nonmetals . Hydrogen is highly chemically reactive, like the other s - block elements, but helium is a virtually unreactive noble gas . </P>

Where is the f block located on the periodic table