in today's video we're going to explore how ions are made and why some atoms are more likely to form ions than others an ion is just a charged particle so it could be a single atom like n a plus or a group of atoms such as a hydroxide ion which is o h minus as you've seen in our video on electron structure ions are formed when atoms gain or lose electrons and they do this in order to have a full outer shell so that they're more stable now one of the interesting things about the periodic table is that the group number tells us how many electrons the atoms of that group have in the outermost shell so group one elements have one electron in the outermost shell group two elements have two and so on in order to become stable though atoms need to lose or gain electrons until their outermost shell is full but losing and gaining electrons requires energy so the atoms who only have to lose or gain one or two electrons are much more likely to do so in form ions because it requires less energy for example group one elements which we call the alkaline metals only have to lose one electron to a full outer shell which doesn't require very much energy so they easily lose that electron to become one plus ions similarly group two elements can easily lose two electrons to become two plus ions and the same goes for group six which gains two electrons to become a two minus ion and group seven which has to gain one electron however the elements in groups three four and five would have to lose or gain three or four electrons which would require loads of energy and so this doesn't happen very often and we generally don't see these elements as ions just like we can write chemical equations between different atoms we can also write equations to show the gain or loss of electrons for example in the case of sodium we could write that a sodium atom goes to form a sodium ion plus an electron or let's say we were looking at chlorine we could write that chlorine plus an electron forms a one minus chloride ion so as you can see if the atom is becoming a positive ion and losing electrons then we place the electron on the right of the reaction while if the atom is gaining electrons we place the electron on the left to show that it's combining with the atom sometimes atoms will lose or gain at multiple electrons though so for atoms like magnesium in group two they'll form a two plus ion and two electrons so we would write mg goes to form mg2 plus plus two electrons or for example of a group six element we could take oxygen and right that oxygen plus two electrons goes to form an oxygen two minus ion anyway that's everything for now if this helped you out at all then please do give us a like and we'll see you next time