2017年1月10日 · $\ce O$ is a free oxygen atom and $\ce{O2}$ is two oxygen atoms chemically bound to form an oxygen molecule. There is no common analogy for $\ce C$, but $\ce{N2}$ is called nitrogen, $\ce{H2}$ is hydrogen and $\ce{Cl2}$ is chlorine, each having the same name as that of their constituent elements.

2018年11月25日 · The first pure substance containing only the element oxygen to be isolated was dioxygen ($\ce{O2}$), in 1774, though it was called "dephlogisticated air" until 1777 when Lavoisier used the term "oxygen" for the first time. This was some 30 years before John Dalton even proposed the first empirical atomic theory.

2015年9月5日 · Element traditionally is a term at the macroscopic scale, it refers to the nature of a substance (either element or compound). However, it is also used to refer to an atom-type, such as in the statement that "acetic acid contains oxygen", meaning that it contains oxygen atoms.

2017年4月21日 · Element abundance. there is nothing as familiar to mankind (in terms of the frequency in their occurrence) as the reactions involving this compound. This is because frequency depends on abundance. If you have a look to the element abundance on the earth oxygen is the first: Element Amount O 44.8 Mg 22.

2015年4月2日 · But, then I read that a single oxygen atom can bind with another element to form a compound, but it's a diatomic element with two atoms. Please can someone enlighten some clarity on this subject. Also, it would help to see some examples to see the differences and context of how these diatomic molecules and elements interact.

2016年9月27日 · Oxygen can exist temporarily in monatomic form, as ordinary diatomic oxygen in air, as triatomic ozone, even as $\ce{O8}$, a red solid. All are the same element, just different allotropes. That said, it was difficult for the early chemists to prove that different allotropes were really the same element.

The slight drop in ionisation energy at oxygen warrants a separate explanation. If you observe closer, you realise that the first three p-electrons (boron to nitrogen) are added as α spins while oxygen is the first element to obtain a β spin electron. A single β electron at first approximation has three degenerate orbitals it can populate.

2022年9月15日 · The first IUPAC definition (1-A) implies that you can e.g. say water is made up of the elements hydrogen and oxygen, even though water itself is a compound and not an element. The IUPAC definition also makes clear that you can use the term element either at the macroscopic level ("This sample is pure iron, an element") or at the particular ...

2017年9月29日 · That means if oxygen combines with an element which is more electronegative than it will surely possess a positive oxidation state. Fluorine being the most electronegative element (electro negativity of 4.0 on Pauling scale) will in any case (except in fluorine gas) have an oxidation state of -1. So that's the reason why oxygen has a +2 ...

2015年9月17日 · It would be more correct to describe ozone as an allotrope of oxygen. Dioxygen (about 1 in five of the molecules making up air) is another allotrope. The periodic table describes the atoms that make up elements as this is the most fundamental property.