{"id":7945,"date":"2018-06-03T12:01:03","date_gmt":"2018-06-03T12:01:03","guid":{"rendered":"https:\/\/www.experimentoscientificos.es\/?page_id=7945"},"modified":"2018-11-16T14:27:28","modified_gmt":"2018-11-16T14:27:28","slug":"enlaces-quimicos","status":"publish","type":"page","link":"https:\/\/www.experimentoscientificos.es\/en\/enlaces-quimicos\/","title":{"rendered":"Chemical bonds"},"content":{"rendered":"
The\u00a0chemical bonds <\/b>are the processes responsible for the interactions between the atoms<\/a> and molecules.\u00a0<\/b>\u00a0The interactions between atoms and molecules is such a complex process that quantum physics comes into play. In simple terms, a\u00a0chemical bonding<\/b>\u00a0is the force that exists between atoms once a stable system has been formed. We can classify chemical bonds into 3: ionic bond<\/a>, covalent bond<\/a> y metallic bond<\/a>.<\/p>\n All the bodies we know, from molecules, crystals, metals and gases are linked by chemical bonds. It is the chemical bonds that will determine the both physical and chemical properties of the objects<\/strong>. The type of bonding between atoms and molecules will depend mainly on the atomic structure, number of electrons and electronegativity<\/a> of the atom.<\/p>\n Single atoms are usually not chemically stable elements (with the exception of the noble gases). This is due to the number of electrons in the atoms. The electrons in the atom are distributed in different orbitals (energy levels) around the atom, from the first level to the last one they can complete. Each level must have a certain number of electrons to be considered stable. If the last level is not completed, the atom tends to lose electrons or pick up electrons to create a stable structure.<\/p>\n The number of electrons an atom must lose or gain to complete the last level is known as the oxidation number<\/a>\u00a0or valence electrons. The oxidation number corresponds to the number with which the atom is charged. It will be positively charged if it loses electrons and negatively charged if it has to gain electrons to complete the last shell.<\/p>\n Although the bonds are complex and must be explained by quantum theory, through some simplification rules we will look at 3 types of bonds: ionic bond<\/strong>, covalent bond<\/strong> y metallic bond<\/strong>.<\/p>\n The basis of a\u00a0ionic bond<\/a>\u00a0is a bond where an atom with extra electrons to complete the last shell is joined with an atom that lacks electrons, so that both atoms are complete.<\/p>\n An ionic bond can also occur between a negatively charged molecule and a metal (positively charged). This is the case with sulphates, which are formed by ionic sulphate bonds of different metals, hence their solubility.<\/p>\n PROPERTIES OF IONIC BONDS<\/strong><\/p>\n The elements with ionic bonds have common properties, which are detailed below:<\/p>\n EXAMPLE OF AN IONIC BOND<\/strong><\/p>\n The most typical example of ionic bonding is that of common salt, NaCl<\/strong>.<\/p>\n Na<\/strong>Sodium has a valence of 1+, as it has one electron left over to leave its electron shells complete. Chlorine,\u00a0Cl,<\/strong>\u00a0it lacks 1 electron to complete the third layer, it has valence 1-<\/strong>. In the NaCl bond, sodium gives up an electron to chlorine and chlorine gains that electron. Both atoms are therefore stable and form an ionic bond. See more examples of ionic bonds<\/a>.<\/p>\n The\u00a0covalent bond<\/b>\u00a0is a type of chemical bond that occurs between 2 atoms when they share electrons to complete the last level.<\/p>\n When the difference in electronegativity between atoms is not great enough for an ionic bond to occur. For a covalent bond to occur, the difference in electronegativity between atoms needs to be\u00a0less than 1.7. <\/strong>More information on the covalent bond<\/a>.<\/p>\n Whenever we talk about chemical bonds, the terms valence shell, valence electrons, and valence electrons come up, octet rule<\/a>oxidation number. All these terms are related to each other. Let's look at what each of them refers to in order to understand the chemical bonds between elements in the periodic table<\/a>.<\/p>\n The electrons in a atom<\/a> are distributed in different layers by energy levels. As each layer is completed, it moves on to the second. In the first level, or first orbital, there can be up to 2 electrons, in the second 8, in the third 18, in the fourth 32. The different shells where the electrons are placed are ordered as follows.<\/p>\n The number of electrons an atom has equals the number of protons, and this corresponds to the atomic number<\/a>. The atomic number is given by the position of the element in the periodic table<\/a>.<\/p>\n An atom is stable the more complete each electron orbital is. As soon as it has too few or too many electrons to leave the last shell complete, it will tend to lose or gain them. If it has 7 electrons in the second shell, it will tend to gain one, so it gains 1 electron or, in other words, a negative charge. It will remain in a -1 oxidation state. This is the\u00a0oxidation number<\/strong>\u00a0 o\u00a0valencia<\/strong>\u00a0of an atom. You can see more detail at\u00a0oxidation numbers<\/a>. This is known as octet rule<\/a> or Lewis law.<\/p>\n Noble gases are the elements that do not react or share with anyone because they already have their last layer complete, hence their stability and low reactivity. This is the tendency of the atoms to complete their energy level with the last layer.\u00a0eight electrons<\/strong>\u00a0in order to achieve\u00a0stability<\/strong>.<\/p>\n The American scientist\u00a0Gilbert Newton Lewis<\/strong>\u00a0was the one who, in\u00a01917<\/strong>postulated the octet rule.\u00a0Lewis<\/strong>\u00a0noted that, by combining with each other, the atoms try to achieve the structural configuration that has the\u00a0noble gas<\/strong>located closer to the\u00a0periodic table<\/strong><\/a>\u00a0of elements.<\/p>\n The electronegativity of an element measures its tendency to attract electrons to itself when it is chemically combined with another atom. The higher it is, the greater its ability to attract electrons. An atom with a very negative electron affinity and a high ionisation potential will attract electrons from other atoms and will also resist letting go of its electrons in the face of external attractions;\u00a0will be highly electronegative.<\/b><\/p>\n Compounds consisting of elements with\u00a0very different electronegativities<\/strong>\u00a0tend to form ionic bonds. For a covalent bond to form between 2 atoms, the difference in electronegativity must be less than 1.7.<\/p>\n <\/p>\n Van der Waals forces are molecular stabilisation forces (they give stability to the bond between several molecules).<\/strong>also known as intermolecular or long-range attractions, and are the\u00a0forces between molecules<\/strong>(forces between\u00a0molecule-molecule<\/strong>).<\/p>\n These forces are weaker than the internal forces that bind the molecule together because they\u00a0depend exclusively on the size and shape of the molecule and can be either attractive or repulsive.<\/span>. They are so weak that they cannot be considered a bond, such as a covalent or ionic bond,\u00a0are only considered an attraction<\/strong>.<\/p>\n To get an idea of how little strength they have, if a covalent bond had a strength of 100, the Van der Waals bond would have a value of 1 (100 times less).<\/p>\n In fact, van der Waals forces\u00a0are the attractive or repulsive forces between molecules<\/strong>\u00a0(or between parts of the same molecule)\u00a0other than those due to a link<\/span>\u00a0(covalent, ionic or metallic). They include attractions between atoms, molecules and surfaces outside normal bonds.<\/p>\n Before explaining each of the possible types of Van der Waals forces, it is important to know that there are polar and non-polar molecules.<\/p>\n <\/p>","protected":false},"excerpt":{"rendered":" Chemical bonds are the processes responsible for the interactions between atoms and molecules. The interactions between atoms and molecules is such a complex process that quantum physics comes into play. Simply put, a chemical bond is the force that exists between atoms once a stable system has been formed. We can classify bonds as [...]<\/p>","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_acf_changed":false,"footnotes":""},"acf":[],"yoast_head":"\nWHY CHEMICAL BONDS OCCUR<\/h2>\n
<\/p>\n
CLASSIFICATION OF CHEMICAL BONDS<\/h2>\n
ION BONDING<\/a><\/h3>\n
\n
<\/p>\n
COVALENT BONDS<\/a><\/h3>\n
DISTRIBUTION OF ELECTRONS IN THE ATOM<\/h2>\n
OXIDATION NUMBER. VALENCE SHELL AND VALENCE ELECTRONS<\/span><\/a><\/h3>\n
OCTET RULE<\/span><\/span><\/a><\/h3>\n
ELECTRONEGATIVITY<\/span><\/h2>\n
<\/p>\n
VAN DER WAALS FORCES<\/h2>\n