professor Dave here, let's learn about chemical bonds a molecule is made up of atoms that are participating in chemical bonds with one another. there are different types of bonds that we will want to be able to describe and the key to their formation has to do with the difference in electronegativity between the two atoms participating in the bond. if the difference is more than about 2 like with sodium and chlorine, chlorine will steal an electron from sodium chlorine really wants another electron, sodium really wants to get rid of one so everybody wins. the result is a positively charged sodium ion and a negatively charged chloride ion. particles of opposite charge have an electrostatic attraction so these two ions hang out together by forming an ionic bond. this is a very strong attraction because it is happening between ions that have a formal charge. bond, ionic bond. electrons taken not shared. speaking of shared electrons if the difference in electronegativity between the two atoms is less than about 1.7 no electrons are stolen but instead the two atoms share two electrons. the electron from this atom feels the attraction from the other nucleus and so does the electron from this atom, so the atoms share the two electrons to form a covalent bond. covalent bonds can be polar or nonpolar. if the electronegativity difference between the atoms is not high enough to cause ionization but is at least more than 0.5, like with hydrogen and chlorine, instead of completely stealing the electron the chlorine will just sort of hog the electrons in the resulting covalent bond. the more electronegative atom in a polar covalent bond pulls the electron density towards itself and as a result of the slight electron excess we call this atom partially negative, denoted by the symbol Delta minus. the atom whose electron is getting pulled away is slightly electron deficient and therefore partially positive or Delta plus. if the electronegativity difference is less than 0.5 the covalent bond is said to be non polar. in a nonpolar covalent bond the electrons are shared more or less evenly or in the case of two atoms of the same element, precisely evenly. the atoms will have no partial charges at all. other than strange phenomena like metallic bonding these are the main ways atoms bind to one another remember that you can predict the type of bond that will form between two elements by comparing their electronegativites. if the difference is very low, less than 0.5 or so, it will be a nonpolar covalent bond where the electrons are shared evenly. between about 0.5 and 1.7 it'll be a polar covalent bond with the electrons are shared but one atom holds them more tightly. if above 2 or so one atom will simply steal an electron from the other and you'll get ions that are joined by on ionic bond. thanks for watching guys, subscribe to my channel for more tutorials and as always feel free to email me