1. Chemical Bonding In the next unit, we will discuss how atoms join together to form a chemical bond. There are 3 main types of chemical bonds; – Ionic Bonds – Metallic Bonds – Covalent Bonds

2. Ionic Bonding Electron Dot Diagrams (Lewis Diagrams) – An electron dot diagram shows the number of valence electrons around an atom. – The group number tells us how many valence electrons the atom has.

3. Ionic Bonding Electron dot diagrams – Draw the electron dot diagrams of Calcium, Aluminum, and oxygen.

4. Ionic Bonding Ionic Compounds are substances that form when a cation and an anion attract and ‘stick’ to each other. The force that’ glues’ the ions together is an electrostatic interaction. In other words, opposite charges attract.

5. Ionic Bonding How do we know the sign and magnitude of the charge an ion will form? GroupCharge 1 +1 2 +2 3 +3 4 +4/-4 5 -3 6 -2 7 -1 8 0

6. Ionic Bonding When a cation and an anion are attracted to each other, an ionic bond has formed.

7. Ionic Bonding What happens when a calcium ion and a chloride ion come together? What do you think the ratio of cations to anions would be?

8. Ionic Bonding Rules for forming and writing ionic compounds; – The sum of the positive and negative charges has to equal zero. Ionic compounds are neutral. – The cation is written first in the formula. – A subscript is used to tell us how many of each atom is in the ionic compound. Na 2 O

9. Ionic Bonding Write the chemical formula for the ionic compound that will form from the following elements; – Magnesium and sulfur – Potassium and nitrogen – Barium and bromine – Aluminum and oxygen

10. Ionic Bonding Some ions are polyatomic, they consist of more than one atom. -2-3 NO 2 -1 = nitriteSO 3 -2 = sulfitePO 4 -3 = phosphate NO 3 -1 = nitrateSO 4 -2 = sulfate C 2 H 3 O 2 -1 = acetate

11. Ionic Bonding Writing chemical formulas of ionic compounds that contain a polyatomic ions; – Same ‘rules’ as before but if there is more than one polyatomic ion in the compound, we need to use ( ). – NaNO 3 Ba(NO3) 2 Mg(C 2 H 3 O 2 ) 2

12. Ionic Bonding Write the formula of the ionic compound when the following ions bond; – Barium ion and the carbonate ion – Sodium ion and the hypochlorate ion – Magnesium ion and the sulfate ion – Aluminum and the hydroxide ion – Lithium and the nitrate ion

13. Naming Ionic Compounds All you have to do is to say the name of the cation, then the root of the anion with the suffix ‘ide’. Na 2 S = sodium sulfide

14. Naming Ionic Compounds If the anion or cation is polyatomic, use the name of it without modifying it. Na 2 SO 4 = sodium sulfate

15. Naming Ionic Compounds If the cation is a trasition metal, write a roman numeral to indicate its charge. CoSO 4 = cobalt (II) sulfate

16. Naming Ionic Compounds Name these ionic compounds; – CaF2 = calcium fluoride – Mg 3 N 2 = – AlPO 4 = – Ba(NO 3 ) 2 =

17. Naming Ionic Compounds Name these ionic compounds; – CuF2 = copper (II) fluoride – Mg 3 N 2 = – Pb 3 (PO 4 ) 2 = – Ba(NO 3 ) 2 =

18. Ionic Compounds Some physical properties; – Very high melting point. – Very high boiling point. – Brittle – They have a crystalline structure

19. Ionic Compounds Crystalline structure of ionic compounds; – A crystal is an orderly arrangement of atoms.

20. Ionic Compounds Crystalline structure of ionic compounds; – These crystalline structures ‘lock’ the atoms of the compound in place. – As a result, they form a structurally strong solid.

21. Ionic Compounds Crystalline structure of ionic compounds; – The 3-dimensional arrangement of atoms is referred to as a lattice, not lettuce. – The lattice energy is the amount of energy required to disrupt the 3- dimensional arrangement of atoms and change the solid ions into gaseous ions. – The lattice energy of NaCl is 13,500 Joules for every gram of NaCl.

22. Ionic Compounds Crystalline structure of ionic compounds; – There are many types of crystalline shapes of ionic compounds.

23. Ionic Compounds Crystalline structure of ionic compounds; – There are many types of crystalline shapes of ionic compounds.

24. Metallic Bonding What happens when two metallic atoms interact? Do they ionize? Do they give away their electrons?

25. Metallic Bonding When metallic atoms bond, the metallic nuclei donate their electrons to all of the atoms in the sample.

26. Metallic Bonding This type of bonding between metallic nuclei is called the ‘sea of electrons’ model. It appears as if the metal atoms are floating in an ocean of valence electrons.

27. Metallic Bonding This type of bonding gives metals some unique properties. Metals are malleable – They can be bent and they will stay in the shape.

28. Metallic Bonding This type of bonding gives metals some unique properties. Metals are ductile – They can be pulled into long and thin wires.

29. Metallic Bonding An alloy is a mixture of metals. Some common alloys are; – Brass (Cu and Zn)

30. Metallic Bonding An alloy is a mixture of metals. Some common alloys are; – Bronze (Cu and Pb)

31. Metallic Bonding An alloy is a mixture of metals. Some common alloys are; – 14 carat gold (Au and Ni)

32. Metallic Bonding An alloy is a mixture of metals. Some common alloys are; – 14 carat gold (Au and Ni)

33. Metallic Bonding An alloy is a mixture of metals. Pure Gold (not an alloy); – 24 carat gold (100 % Au)