[Music] ionic bonding is when atoms transfer electrons to form charged particles called ions this happens between a metal and a non-metal here's the key idea metals always lose electrons forming positive ions called cat ions non-metals always gain electrons forming negative ions called annions these oppositely charged ions attract forming a strong electrostatic force which is the ionic bond now how does this ionic bonding compared to coalent bonding if you remember from our coalent bonding video non-metals don't like to give up electrons so they share them instead that's why coalent bonding happens between two non-metals but in ionic bonding metals are happy to give away electrons and nonmetals are eager to take them this electron transfer creates ions which attract each other forming a strong bond let's take a look at a real world example table salt sodium is a metal with one electron in its outer shell chlorine is a non-metal with seven electrons sodium loses its one electron forming an Na+ ion and chlorine gains that electron forming a Cl minus ion the Na+ and Cl minus ions attract forming an ionic bond and just like that you have sodium chloride or table salt so how can you tell if a compound is ionic look for these signs it's made of a metal and non-metal it has a high melting and boiling point it conducts electricity when molten or dissolved for example table salt dissolves in water and can conduct electricity but what about magnesium oxide let's break it down magnesium is a metal with two electrons in its outer shell it loses both electrons to form Ng2+ oxygen is a non-metal with six electrons in its outer shell it gains those two electrons to form O2 minus the Mg2 plus and O2 minus ions attract forming an ionic bond now let's test your understanding with some IGCSE style questions grab a pen and paper and try them out question one potassium reacts with florine to form an ionic compound potassium fluoride a describe how potassium and florine form an ionic bond b write the electron configuration of potassium and florine before and after bonding pause the video and give it a try here's the answer potassium is a metal with one electron in its outer shell it loses this electron forming a K+ ion florine is a non-metal with seven electrons in its outer shell it gains one electron forming an F minus ion the K plus and F minus ions attract forming an ionic bond now let's look at the electron configurations potassium is in period 4 and group one that means it has three fully filled shell and its outermost shell has one veence electron so its configuration is 28 81 after losing one electron the fully filled shell underneath is exposed its electron configuration therefore is 2 88 florine is in group 7 and period 2 so its electron configuration is 27 after gaining one electron it becomes 2 and 8 question two a solution of sodium chloride conducts electricity but solid sodium chloride does not explain why pause the video and give it a try in solid sodium chloride the ions are locked in place in a lettuce structure so they can't move but when sodium chloride is dissolved in water or melted the ions are free to move allowing the solution to conduct electricity let's quickly recap what we've learned today ionic bonding happens between metals and non-metals through electron transfer metals always lose electrons to form cat ions non-metals always gain electrons to form n ions ionic bonds form due to strong electrostatic attractions between these oppositely charged particles ionic compounds conduct electricity only when dissolved or molten what exactly is coalent bonding well it happens when two non-metal atoms share electrons to achieve a full outer shell unlike ionic bonding where electrons are transferred non-metals don't like giving away electrons instead they share imagine you and a friend each have half a sandwich but you're both still hungry instead of keeping your half separate you combine them to make one full sandwich that's how coalent bonding works both atoms combine their electrons so they feel complete coalent bonds are strong and commonly found in gases liquids and solids all right let's look at two important examples methane CH4 and water H2O methane is made of one carbon atom and four hydrogen atoms carbon needs four more electrons and each hydrogen needs one by sharing carbon forms four single coalent bonds making methane a stable molecule water consists of one oxygen atom and two hydrogen atoms oxygen needs two more electrons and each hydrogen needs one more they share electrons forming two single covealent bonds remember in coalent bonding atoms always share electrons instead of transferring them now it's time to test your understanding with two IGCSC style questions question one methane and oxygen both form coalent bonds a explain why methane forms coalent bonds b draw a dot and cross diagram for an oxygen molecule pause the video and try for yourself here's the answer methane forms coalent bonds because carbon and hydrogen are both non-metals since non-metals do not give away electrons they share them allowing each atom to have a full outer shell oxygen O2 forms a double coalent bond because each oxygen atom has six outer electrons and needs two more to complete its shell question two which of the following pairs of elements are most likely to form a covealent bond a sodium and chlorine B oxygen and hydrogen C magnesium and oxygen pause the video and try for yourself the correct answer is B oxygen and hydrogen because they are both non-metals sodium and chlorine are a metal and a non-metal and they would form an ionic bond the same is true for magnesium and oxygen [Music] unlike ionic or coalent bonding metallic bonding is the attraction between positively charged metal ions and a sea of deoized electrons surrounding it this unique structure gives metals their key properties let's take a closer look in a metal atoms lose their outer electrons forming positive metal ions arranged in a lettuce structure the lost electrons don't stay with one atom instead they move freely throughout the entire structure creating a so-called sea of free electrons these deoized electrons hold the metal ions together with a strong force of attraction this special bonding structure explains why metals have these three important properties high electrical conductivity the free moving electrons allow metals to conduct electricity and heat easily this is why copper is used in electrical wiring malleability and ductility metals can be bent shaped and stretched without breaking their positive ions are arranged in layers that can slide over each other while still being held together by the sea of electrons high melting and boiling points the strong attraction between metal ions and the deoized electrons requires a lot of energy to break making metals solid at room temperature with high melting points now how does metallic bonding compare to ionic and coalent bonding ionic bonding happens between metals and non-metals where electrons are transferred to form charged ions like sodium chloride it only conducts electricity when dissolved or molten covealent bonding happens between non-metals where electrons are shared forming molecules like water most coalent compounds don't conduct electricity metallic bonding happens only between metals instead of transferring or sharing electrons metals have a sea of deoized electrons making them great conductors in any state which is why copper is used in wiring for more information about ionic and coalent bonding check out my videos now let's test your understanding with two IGCSC style exam questions question one why are metals good conductors of electricity pause the video and give it a try the answer is metals have deoized electrons that are free to move and can carry electric charge throughout the structure these electrons allow electricity to pass through easily question two magnesium and sodium are both metals explain why magnesium has a higher melting point than sodium in terms of metallic bonding pause the video and give it a try magnesium forms Mg2+ ions while sodium forms Na+ ions since magnesium ions have a greater charge they attract the deoized electrons more strongly creating stronger metallic bonds as a result more energy is needed to break the metallic bonds in magnesium giving it a higher melting point than sodium [Music]