Short answers, pulled from the story.
Joseph Priestley independently isolated oxygen in 1774 while Carl Wilhelm Scheele produced it as early as 1771 but did not publish until 1777. Antoine Lavoisier named the element oxygen in 1777 after deriving the name from the Greek roots oxys meaning acid and genes meaning producer.
The Great Oxygenation Event occurred approximately 2.45 billion years ago during the Neoarchean-Paleoproterozoic boundary. This event was driven by the photosynthetic activity of cyanobacteria which used sunlight to split water molecules and release oxygen as a byproduct.
Antoine Lavoisier named oxygen in 1777 by deriving the name from the Greek roots oxys meaning acid and genes meaning producer. He mistakenly believed that oxygen was a constituent of all acids although Sir Humphry Davy later proved that acids like hydrochloric acid did not contain oxygen.
Polish scientists Zygmunt Wróblewski and Karol Olszewski from Jagiellonian University successfully liquefied oxygen in a stable state in 1883. Oxygen condenses at 90.20 Kelvin and freezes at 54.36 Kelvin during this process.
The rise in oxygen levels was catastrophic for the anaerobic life that dominated the early Earth because oxygen is toxic to many of these organisms. The concentration of oxygen fluctuated greatly during this period eventually reaching levels that allowed for the evolution of more complex life forms.