Ionic Bonding Starter: Find the following elements on the periodic table and identify what group they are in. a) F b) Ca c) S d) Ne e) C Draw electron shell diagrams for these elements. Predict the number of electrons in the outer shells of the following atoms: a) In b) Br c) Ge Extension: Which of the above atoms from Q1 and Q3 is the least reactive? Explain your answer.

Nobel gases

Noble Gas Configurations The noble gases (the elements in group 0) have stable electronic configurations. Helium (He) has 2 electrons in its outer shell. The others have 8 electrons in their outer shells. When other elements react with one another they often finish with noble gas configurations. He Ne Ar Kr Xe Rn

Atoms What is the overall charge on a sodium atom? Explain your answer in terms of the particles that make up a sodium atom. Sodium atoms have no overall charge. It has 11 positively charged protons and 11 negatively charged electrons. These charges cancel one another out.

Forming Ions One way in which atoms can gain a noble gas configuration is by losing or gaining electrons. An atom which loses electrons will have more protons than electrons. Therefore it becomes positively charged. What would be the charge of an atom which had gained 2 electrons? 2- The convention for charges is to write the number then the charge. For a single positive or negative charge you would not normally write the number 1, simply “+” and “-”. + Na

Forming Ions Refer back to the electron shell diagrams from the starter. a) F b) Ca c) S d) Ne e) C For each, state how many electrons it needs to gain or lose to get a noble gas configuration. Predict the charge on each of these ions

Forming Ions Draw diagrams to show the electron transfer for the following elements to become ions. Include the charge on each of these ions Li F Mg O

W/S C3b2

Forming ionic compounds Cl Na A sodium atom has an electronic configuration of 2,8,1 It tends to lose one electron when it forms ions. A chlorine atom has an electronic configuration of 2,8,7 It tends to gain one electron when it forms ions.

Forming ionic compounds Na Cl When sodium and chlorine react with one another, the outer shell electron of sodium is transferred to the chlorine atom. These oppositely charged ions attract one another. This attraction of oppositely charged ions is called ionic bonding.

Dot and Cross Diagrams Na Cl To help highlight the transfer of electrons in ionic compounds, they are represented as dots/circles for one atom and crosses for the other. Draw dot and cross diagrams for the ionic compounds formed by: Magnesium and Sulphur Magnesium and Chlorine

Dot and Cross Diagrams 2+ 2- Mg needs to lose 2 electrons Sulphur needs to gain 2 electrons.

Dot and Cross Diagrams + - - 2 Mg needs to lose 2 electrons Cl Mg Mg needs to lose 2 electrons Chlorine needs to gain 1 electron. Each Mg combines with 2 Cl atoms. The formula of magnesium chloride is MgCl2. - Cl

Ionic Bonding + - + - + - + - When solid, positive and negative ions attract one another, forming a giant lattice structure. The bonds are strong and so ionic substances will have high fixed points. The ions cannot move relative to one another so solid ionic substances will not conduct electricity + - + - + - + -

Conductivity of molten ionic substances What is electricity? Write a definition in your books. Electricity is the movement of charged particles, most often electrons, to create a current

Conductivity of molten ionic substances When molten (liquid), the lattice breaks apart the ions (which are charged, of course) are free to move relative to each other. Therefore ionic substances conduct electricity when MOLTEN - + - + - + + - - + - + + + + - - THEY DO NOT CONDUCT ELECTRICITY WHEN SOLID

Conductivity of ionic solutions When in solution the ions are free to move relative to each other. Therefore ionic substances conduct electricity when in solution. + - - + - + - +

Reactivity of Group 1 Li Na K Do you remember the demonstration of the reaction between the group 1 metals and water? Which was the most reactive... Discuss the reasons why you think this may be the case.

Reactivity of Group 1 Li Na K There are extra electron shells between the valence electron on potassium when compared to lithium and sodium. This means that the electron is more easily lost and the resultant reaction is more energetic.

Reactivity of Group 7 F Cl Br Which is the most reactive of the 3 halogens drawn here? Discuss the reasons why you think this may be the case.

Reactivity of Group 7 F Cl Br As with the group 1 metals the number of electron shells between the nucleus and valence electron shell increases down the group. This reduces the attractive force of the nucleus so it is harder for the atom to gains an electron