now that we've had our whirlwind tour of the periodic table let's look at different types of bonds that atoms can make so the first type that we're going to talk about is called an ionic bond and ionic bonded atoms can form something called a compound and a compound is a substance that is made up of two or more types of atoms so we'll start with two atoms sodium and chlorine and we'll look at sodium we'll see that it's in our first group in the third period so sodium has 11 protons it has 11 electrons and the first two electrons are in that first shell the next eight electrons will be in the second shell and then we have that 11th electron that's hanging out in that third electron shell that's why it's the first element in the third period because we're starting to fill that third electron shell now when we go across the period over to group seven here we find chlorine chlorine has 17 protons and therefore 17 electrons and we fill the shells in order so we have the first two electrons filling the first shell then we have the next eight electrons filling the second shell and then we have seven electrons occupying the third shell so what we can see straight away is that we have an extra space in here that needs to be filled over here we have seven spaces that would need to be filled in order to complete these electron shells now as we know atoms like to have complete electron shells so for sodium to do that it could do one of two things it could find seven other electrons somewhere or it could find a way to get rid of one of them and revert down to the next little shell by the same token chlorine over here would do well to find another electron and so what happens if sodium when sodium and chlorine are in proximity sodium can give up an electron and give it to chlorine so now one electron that was in the third shell of sodium can now come over to chlorine and fill that one space and the third shell of chlorine and at the same time get rid of the third shell of sodium so now we have a completely filled second shell so what we get when we do that our two charged particles and we will call these ions so an ion is any atom that's gained or lost electrons so when an atom gains or loses an electron it gives up as atom status and becomes an ion so now we have sodium ion which is positively charged by virtue of the fact that it has one more proton than it does electrons since it's given one of its eleven electrons away it now has ten and it has a positively charged proton now that is not balanced by the electron over here we have chlorine which has now gained an electron so we have 18 negative charges to the 17 positive charges in the nucleus so we now have a negatively charged ion over here so we have positively charged sodium then we have negatively charged chlorine and so ions come in two types cat ions which are our positively charged ions so this would be sodium ion and we can think of cat ion being an easy thing to remember for positive because it has a T in the middle of it that looks like the plus symbol in representing a positive charge a and an ion on the other hand which is what we get when we get chloride ion and an ion is a negatively charged ion and you can remember negative by the end and an ion so an ion in like negative so anions are negatively charged ions and cations are positively charged ions and when you have this kind of giving an electron from where atom to another to make two ions then we have oppositely charged things and opposites attract so sodium and chloride will get together and form an ionic bond which creates a compound that we know is table salt so this is the stuff we sprinkle over our food now what's interesting about this is that this is not a very strong bond and we all know what happens to salt when we put it in water it dissolves and it dissociates so the crystals that are formed when we create an ionic compound like sodium chloride the crystals that are formed when it's a solid will dissolve and what we call ionize when we put them in water so that now we'll have sodium ions floating around in water and chloride ions floating around in water and the compound has dissociated into its component ions so it's not a very strong bond it's fairly easily broken the next type of bond we'll look at is a covalent bond