Nitrogen
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Nitrogen is a chemical element; it has symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common eleme
Liquid nitrogen (N2 at below −196 °C)
Daniel Rutherford, discoverer of nitrogen
Molecular orbital diagram of dinitrogen molecule, N2. There are five bonding orbitals and two antibonding orbitals (marked with an asterisk; orbitals involving the inner 1s electrons not shown), giving a total bond order of three.
Nitrogen trichloride
Alkali metal
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The alkali metals consist of the chemical elements lithium, sodium, potassium, rubidium, caesium, and francium. Together with hydrogen they constitute group 1, which lies in the s-block of the periodi
Petalite, the lithium mineral from which lithium was first isolated
Johann Wolfgang Döbereiner was among the first to notice similarities between what are now known as the alkali metals.
Lepidolite, the rubidium mineral from which rubidium was first isolated
Spodumene, an important lithium mineral