<Li> Beryllium (Be) has one of the highest melting points of all the light metals . Small amounts of beryllium were synthesised during the Big Bang, although most of it decayed or reacted further within stars to create larger nuclei, like carbon, nitrogen or oxygen . Beryllium is classified by the International Agency for Research on Cancer as a group 1 carcinogen . Between 1% and 15% of people are sensitive to beryllium and may develop an inflammatory reaction in their respiratory system and skin, called chronic beryllium disease . </Li> <Li> Boron (B) does not occur naturally as a free element, but in compounds such as borates . It is an essential plant micronutrient, required for cell wall strength and development, cell division, seed and fruit development, sugar transport and hormone development, though high levels are toxic . </Li> <Li> Carbon (C) is the fourth most abundant element in the universe by mass after hydrogen, helium and oxygen and is the second most abundant element in the human body by mass after oxygen, the third most abundant by number of atoms . There are an almost infinite number of compounds that contain carbon due to carbon's ability to form long stable chains of C--C bonds . All organic compounds, those essential for life, contain at least one atom of carbon; combined with hydrogen, oxygen, nitrogen, sulfur, and phosphorus, carbon is the basis of every important biological compound . </Li> <Li> Nitrogen (N) is found mainly as mostly inert diatomic gas, N, which makes up 78% of the Earth's atmosphere by volume . It is an essential component of proteins and therefore of life . </Li>

Which period of the periodic table contains more metallic elements