as you can see from the periodic table most elements are metals and we find them towards the bottom left of the table one of the key features of metals is that they form positive ions when they react like a calcium two plus ion whereas non-metals either don't form ions like carbon or they form negative ions like chloride one minus to understand why this is we need to consider the electron arrangements of the atoms and remember from previous videos that all atoms won't have a full outer shell of electrons in order to be stable if an element is found on the left of the periodic table then it won't have many electrons in its outermost shell for example calcium in group two has two electrons in its outer shell this makes it easy to lose these outer electrons and from a positive ion on the other hand something like chlorine with seven electrons in as outer shell would have to lose all seven of them in order to become a positive ion which would require tons of energy and so doesn't happen another feature of metals is that they tend to become more reactive towards the bottom of the table this is because elements far down the table have lots of shells for example lead which is pb here on the table has six shells so its outermost shell is really far from the nucleus now remember that in any atom is the positive nucleus that holds these negative electrons in place so if the electrons are really far away like those in the sixth shell then the nucleus can't hold on to them so strongly so the atom will lose them more easily and form a positive ion this feature is what makes those metals further down the group more reactive they're just more likely to lose their electrons during a reaction so now that we know how metals and non-metals differ in terms of the electron arrangements we need to consider how this affects their physical properties first all metals have metallic bonding which is a special type of bond that only metals have we take a closer look at it in another video but for now just remember that metallic bonds are very strong and they're responsible for metals physical properties as well as being strong metals are also malleable which means that they can be bent or hammered into shape without snapping they're also great conductors of heat and electricity which is why we use them in electric wires and nearly all of them have high melting and boiling points in fact some of them still won't have melted at 2 000 degrees other properties include being shiny and being sonorous which means they create a ringing sound when you hit them non-metals on the other hand tend to be dull in color bristle which means they easily break like the carbon and your pencil and generally have low melting and boiling points with many of them being gaseous at room temperature there are also poor conductors of electricity and generally have lower densities than the metals which means they weigh less for a given volume lastly we have the transition metals found in the center of the periodic table here in green you can think of these as being typical metals as they have all the mental properties we mentioned before they also have some extra properties though one of these is that transition metals can form more than one ion for example chromium can form two plus three plus and six plus ions and these transition metal ions are often colored for example the aqueous forms of these ones would be blue green and orange the most important practical feature of transition metals though is they make very good catalysts which is an important term to remember we can describe a catalyst as substances which increase the rate of a chemical reaction without being used up themselves for example you'll see later in the course that iron is an important catalyst in the harbor process which are used to make ammonia while nickel is used in the hydrogenation of alkenes which were used to make margarine anyway that's it for today so hope you enjoyed it and we'll see you next time you