![]() By convention, the negative sign shows a release of energy. This affinity is known as the first electron affinity, and these energies are negative. When an electron is added to a neutral atom, energy is released. To use electron affinities properly, it is essential to keep track of signs. Molecules with high electron affinity form very stable negative ions which are important in the chemical and health industry as they purify the air, lift mood, and most importantly, act as strong oxidizing agents. O + e – → O – – ∆H = Affinity = 141 kJ/molĮlectron affinity is one of the most important parameters that guide chemical reactivity. Electron affinities are more difficult to measure than ionization energies.Īn atom of Oxygen in the gas phase, for example, gives off energy when it gains an electron to form an ion of Oxygen. Note that ionization energies measure the tendency of a neutral atom to resist the loss of electrons. In other words, it can be expressed as the neutral atom’s likelihood of gaining an electron. The change in energy (in kJ/mole) of a neutral atom or molecule (in the gaseous phase) when an electron is added to the atom to form a negative ion. In chemistry and atomic physics, the electron affinity of an atom or molecule is defined as: Hydrocarbon combustion also contributes to climate change by producing emissions such as carbon dioxide.Electron Affinity and Electronegativity of OxygenĮlectron Affinity of Oxygen is 141 kJ/mol.įirst Ionization Energy of Oxygen is 13.6181 eV. Fossil fuel combustion supplies around 95% of the world's primary energy. All three components (fuel, oxidant, energy) must be present for the combustion reaction to occur.Ĭombustion of fossil fuels such as methane, shown in Figure 2 below, produces carbon dioxide, water vapour, and energy. The third component of combustion is a "boost" of energy needed in order to start the reaction - the activation energy. Combustion is the reaction of a compound (the fuel) with an oxidant (which is usually molecular oxygen) to produce oxides. Molecular oxygen is important for combustion - especially in the combustion of fuels for energy. Some physical properties of molecular oxygen: Oxygen is also important in creating many chemical feedstocks, such as ethylene oxide. Oxygen (as a compressed gas) is also used widely in welding and metal cutting, and as an oxidizer in rocket engines. Industrially, oxygen is used to remove sulfur and carbon impurities during smelting. Molecular oxygen is provided therapeutically in oxygen therapy and hyperbaric chambers, and is also included in breathing gas for space exploration and SCUBA diving. Since animals (including humans) breathe molecular oxygen and require it for metabolism, it is important medically. We rely on photosynthesis of plants to replenish the molecular oxygen in the atmosphere - if photosynthesis stopped, eventually the atmospheric oxygen content would drop to near zero. Molecular oxygen is very chemically reactive, and tends to form oxides by reaction with other elements and compounds quite easily. It's also essential for fossil fuel combustion. Molecular oxygen is essential for life, as it is used for respiration by many organisms. Molecular oxygen (O 2) is a diatomic molecule that is composed of two oxygen atoms held together by a covalent bond. Model of molecular or diatomic oxygen, composed of two oxygen atoms bonded together. ![]()
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