Describe how an ionic bond is formed, including bond diagrams Learning Objective To be able to: Describe how an ionic bond is formed, including bond diagrams Key Words: Ion, charge, electrons

Draw the electronic structure of: Hydrogen Lithium Sodium Saturday, 11 May 2019 Ionic Bonding Date and title in books. You need a pen, pencil & ruler. Starter Activity – 5 minutes Draw the electronic structure of: Hydrogen Lithium Sodium

Describe the properties of ionic substances Target 9-1 Identify what is meant by an ion and if an atom will lost or gain electrons (F/H) Target 4-9 Describe an ionic bond, drawing diagrams (H) Target 5-9 Describe the properties of ionic substances Extension: Application of Knowledge Target 8/9 Describe the limitations of different ways of drawing an ionic bond Learning Outcomes

Ions Ions are charged particles. If an atom loses an electron it becomes a positive ion If an atom gains and electron it becomes a negative ion.

Ionic Bonding Negative and positive ions can join together (bond) to form a compound. When they do this we call it an ionic bond. For instance Na+ and Cl- form an ionic bond and become NaCl.

The Definition An ionic compound is a giant structure of ions. Ionic compounds are held together by strong electrostatic forces of attraction between oppositely charged ions. These forces act in all directions in the lattice and this is called ionic bonding.

Electron Transfer For ionic bonding to happen, electrons must be transferred. In an ionic bond, oppositely charged atoms are held together by electrostatic forces

Group 1 and Group 7 elements Boardworks GCSE Additional Science: Chemistry Ions and Ionic Bonding Group 1 and Group 7 elements The alkali metals, found in Group 1 in the periodic table, react with non-metals to form ionic compounds. Li 2.1 The alkali metals all have one electron in their outer shell. They lose this electron to form an ion with a single positive charge. The halogens, found in Group 7 in the periodic table, react with the alkali metals to form ionic compounds. The halogens all have seven electrons in their outer shell. They gain an extra electron to form an ion with a single negative charge. F 2.7

How are ionic bonds formed? Boardworks GCSE Additional Science: Chemistry Ions and Ionic Bonding How are ionic bonds formed? Sodium chloride is an ionic compound formed by the reaction between the alkali metal sodium and the halogen chlorine. + Na Sodium has 1 electron in its outer shell. Na By losing this electron, it has a filled outer shell and forms a positive ion. 2.8.1 [2.8]+ Chlorine has 7 electrons in its outer shell. - Cl Cl By gaining an electron from sodium, it has a filled outer shell and forms a negative ion. 2.8.7 [2.8.8]-

How are ionic bonds formed? Boardworks GCSE Additional Science: Chemistry Ions and Ionic Bonding How are ionic bonds formed? The positive sodium ions and the negative chloride ions are strongly attracted to each other. - Cl Na + The description of an ionic bond is higher tier for OCR Gateway GCSE Additional Science. It is this electrostatic attraction that forms ionic bonds in sodium chloride and other ionic compounds.

Task 1 1. Draw dot-cross diagrams for: a) Magnesium Oxide MgO b) Sodium Oxide Na2O c) Magnesium Chloride MgCl2 2. Aluminium has 3 outer electrons. How many chlorine atoms will it bond with to become stable?

What is the ratio of ions? Boardworks GCSE Additional Science: Chemistry Ions and Ionic Bonding What is the ratio of ions? Sodium chloride (NaCl) and magnesium oxide (MgO) are simple ionic compounds. In each compound, the metal needs to lose the same number of electrons that the non-metal needs to gain. Na 1 electron Cl Na+ Cl- 2 electrons Mg O Mg2+ O2- This content is higher tier for OCR Twenty-first Century GCSE Additional Science. Both compounds have a 1:1 ratio of metal ions to non-metal ions, which is shown by the formula of each compound.

Ratio of ions in sodium oxide Boardworks GCSE Additional Science: Chemistry Ions and Ionic Bonding Ratio of ions in sodium oxide What is the ratio of ions needed to make sodium oxide? Sodium (2.8.1) needs to lose 1 electron to form a sodium ion but oxygen (2.6) must gain 2 electrons to form an oxide ion . Na Na+ 1 electron from each Na atom O2- O Na+ Na This content is higher tier for OCR Twenty-first Century GCSE Additional Science. Two sodium atoms are required for each oxygen atom and so the ratio of sodium ions to oxide ions is 2:1. From this ratio, the formula of sodium oxide is Na2O.

Ratio of ions in magnesium chloride Boardworks GCSE Additional Science: Chemistry Ions and Ionic Bonding Ratio of ions in magnesium chloride What is the ratio of ions needed for magnesium chloride? Magnesium (2.8.2) needs to lose 2 electrons to form a magnesium ion but chlorine (2.8.7) needs to gain 1 electron to form a chloride ion. Cl Cl- 1 electron for each Cl atom Mg2+ Mg Cl- Cl This content is higher tier for OCR Twenty-first Century GCSE Additional Science. Two chlorine atoms are required for each magnesium atom and so the ratio of magnesium ions to chloride ions is 1:2. From this ratio, the formula of magnesium chloride is MgCl2.

Task 2 Work out the ratio of ions in the compounds to find the formula of the compound Ionic Compound Ratio of ions in compound Formula of compound Sodium Chloride Na- Cl+ 1:1 NaCl Magnesium oxide Calcium chloride Calcium nitrate (NO3)

Properties of Ionic Substances Ionic compounds have regular structures (giant ionic lattices) in which there are strong electrostatic forces of attraction in all directions between oppositely charged ions. These compounds have high melting points and high boiling points because of the large amounts of energy needed to break the many strong bonds. When melted or dissolved in water, ionic compounds conduct electricity because the ions are free to move and so charge can flow.

Limitations What are the limitations to each of these diagrams showing an ionic bond?