Given the high ionization energies found for noble gas atoms, it would seem as though these elements should have little affinity for electrons. However, this is not the case. High electron affinities are usually associated with smaller atoms that have a stronger attraction to electrons than larger atoms. However, things become slightly more complicated for the noble gases. This article takes an in-depth look at why noble gases have no electronegativity and why it’s a good thing! We also take a look at how this impacts other properties of the element and its compounds.
Why Do Noble Gases Have No Electronegativity?
The electronegativity of noble gases is not easily defined. They’re not very reactive, so their electron affinity is generally low. They do not have a defined chemical structure, so they don’t have a valence shell. Their lone pair of electrons is far away from the nucleus, so their electronegativity is almost zero.
How Does the Absence of Electronegativity Impact Properties?
1. Changes in Bonding
Electronegativity plays a crucial role in the formation of chemical bonds. An atom with low electronegativity easily bonds with other atoms, while an atom with high electronegativity forms very infrequent and weak bonds. When mixing two non-electronegative elements, they form compounds where the two elements show no charge difference. In an electronegative-non-electronegative reaction, however, one of the substances is generally oxidized and the other is reduced. For example, magnesium (Mg) is highly non-electronegative, copper (Cu) is moderately electronegative, and sodium (Na) is highly electronegative. When you mix these three elements, then you get a salt-like compound. This is a typical example of a non-electronegative reaction since there is no variation in charges in the end product. When the same three elements are mixed and heated, however, you get an entirely different outcome. Mg and Cu get oxidized and Na gets reduced. This is an electronegative reaction as Mg and Cu lose two electrons while Na gains one electron. This reaction is crucial because, in it, you get an entirely different compound – a metal oxide.
2. Differences in Atomic Radius
The atomic radius of an element, in general, decreases as its electronegativity increases. This means that the atoms of non-electronegative elements have larger atomic radii, while the atoms of highly electronegative elements have smaller atomic radii. What do we mean by atomic radius? Atomic radius is the distance between the two nuclei of two atoms that are bonded together. This difference in atomic radius plays a crucial role in determining which elements can be mixed together and which cannot. When you mix non-electronegative elements, their atomic radius usually varies only due to other factors. When you mix electronegative elements, however, the difference in atomic radius plays a crucial role as the electronegative element is smaller in size compared to the non-electronegative one. This difference in atomic radius impacts properties in various ways.
3. Impact on Chemical Reactivity
The impact of differences in the atomic radius of various elements on chemical reactivity is simple and straightforward – the smaller the atom, the more reactive it is. The reason behind this is that smaller atoms are less stable and more reactive. They also have a higher chance of gaining electrons and being oxidized. This is also true in the case of larger atoms that are less reactive because they are more stable and have less chance of being oxidized. For example, chlorine is highly electronegative, which means that its atomic radius is very small. This means that chlorine is highly reactive and has a strong tendency towards oxidation. This also means that it is volatile, as it is highly reactive. The reactivity of chlorine can be controlled by adding some non-electronegative elements like magnesium. This mixture of chlorine and magnesium is referred to as magnesium chloride. When magnesium chloride is heated, it releases chlorine.
4. Effect on Melting and Boiling Points
One of the most common properties that are often discussed in relation to the difference in atomic radius is the melting and boiling points of various elements. Heavier elements with a larger atomic radius have higher melting and boiling points. Lighter elements with a smaller atomic radius have lower melting and boiling points. This is largely due to the difference in atomic radius as heavier and lighter elements generally have larger and smaller atomic radii, respectively. For example, the melting and boiling points of copper are much higher when compared to the melting and boiling points of sodium. This is because copper has a larger atomic radius compared to sodium. This happens because the electrons of copper are more strongly attracted to the nucleus.
5. Melting and Boiling Points
The type of chemical bonds formed between the atoms of a compound is a key determinant of its melting and boiling points. Strongly electronegative compounds have strong chemical bonds and therefore have high boiling and melting points. For example, sodium chloride has high boiling and melting points due to the formation of ionic bonds between sodium and chlorine. On the other hand, non-electronegative compounds form weak covalent bonds between their atoms, and as a result, they have low boiling and melting points. For instance, carbon dioxide has low boiling and melting points due to its covalent bonding.
6. Ionization Potential
The ionization potential of an element is the energy required to remove an electron from the atom. It is a key determinant of the reactivity of an element. The lower the ionization potential, the more reactive the element is. Generally, strongly electronegative elements have a high ionization potential. For example, fluorine, which has the highest electronegativity, has a very low ionization potential. Non-electronegative elements have low ionization potential. For instance, germanium, which is non-electronegative, has a very high ionization potential.
Why Is It a Good Thing for Noble Gases to Have No Electronegativity?
- Since noble gases have a strong affinity for electrons, they are actually more likely to form a covalent bond than an ionic bond. This means that noble gases are not very likely to form compounds with other elements. This is actually a good thing since it makes noble gases very robust and resistant to corrosion. This is particularly true for helium, which is the only noble gas that is used in industrial applications.
- The lack of electronegativity for noble gases means that they are not very likely to form bonds with other elements. This makes them very useful in a number of contexts. In particular, noble gases make excellent nonreactive solvents for a wide range of substances. They are particularly effective at dissolving ionic compounds, which is why they are so widely used in the electroplating industry. They are also used in the oil and gas industries to decrease corrosion rates and increase corrosion resistance.
- Noble gases have a very high electron affinity and low ionization energy. These two factors mean that these elements have no electronegativity and are very difficult to oxidize. The lack of electron affinity also means that these elements will not form strong bonds with other elements or ions. This makes them ideal for use as nonreactive solvents in a wide range of contexts, including the oil and gas industries, the electroplating industry, and the pharmaceutical industry.
How Can I Recognize Noble Gases?
- Noble gases are characterized by a number of physical properties. The most useful for identification purposes is the fact that noble gases are all monatomic elements.
- This means that all of the atoms will be in the form of individual atoms, rather than in compounds or ions. As a result, their boiling points and melting points will be very high.
- They also have very high ionization energies and electron affinities, as discussed above. Finally, they have very low electronegativities and ionization potentials. These properties can be used to identify noble gases.
Summary
As you can see from this article, noble gases have no electronegativity for a couple of important reasons., The electrons in noble gas atoms are strongly attracted to the nucleus. However, the smaller size of noble gas atoms means that they actually have a stronger attraction for electrons than larger atoms. These two factors mean that noble gases have a very strong affinity for electrons. These elements are therefore more likely to form covalent bonds than ionic bonds. This makes them very robust and resistant to corrosion.
