<div> </div> <div> <strong> Atomic number <span class = "Apple-tab-span" style = "white-space: pre;"> </span>8</strong></div> <div> <strong> Atomic mass <span class = "Apple-tab-span" style = "white-space: pre;"> </span> 15,999 </strong> </div> <div> <strong> Density, kg / m? <span class = "Apple-tab-span" style = "white-space: pre;"> </span> & nbsp ; 1.429 </strong> </div> <div> <strong> Temperature</strong></div> <div> <strong> melting, ° С <span class = "Apple-tab-span" style = " white-space: pre; "> </span> -218.8 </strong> </div> <div> </div> <div> Oxygen is a gas without color, taste or smell; bluish liquid (at low temperatures). The first indications that not all the air, but only its "active" part supports combustion, were found in Chinese manuscripts of the 8th century. Much later, Leonardo da Vinci (1452-1519) considered air as a mixture of two gases, only one of which is consumed during combustion and breathing. The final discovery of the two main constituent parts of air - nitrogen and oxygen, which made an era in science, took place only at the end of the 18th century. Oxygen was obtained almost simultaneously by K. Scheele (1769-70) and J. Priestley (1774). Since Oxygen is a constituent of acids, Lavoisier called it oxygene, meaning "acid-generating". </div>
