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Why do elements combine to form compounds?. Example: Two elements, sodium and chlorine, combine to form sodium chloride.. When sodium is ignited and lowered into a jar of chlorine, it continues to burn and heat is given out. A white solid is left behind which is sodium chloride.. Why do elements c
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1. Chapter 12 Chemical Bonding
2. Why do elements combine to form compounds? Example: Two elements, sodium and chlorine, combine to form sodium chloride.
3. Why do elements combine to form compounds? Sodium and chlorine have higher potential energy compared with sodium chloride. When ignited, the elements combine and release energy.
4. Why do elements combine to form compounds?
5. IONIC BONDING What are ionic compounds?
Compounds made up of both positive and negative ions are called ionic compounds.
6. IONIC BONDING Is there any evidence for the existence of ions?
7. IONIC BONDING Is there any evidence for the existence of ions?
8. IONIC BONDING Is there any evidence for the existence of ions?
9. How and why ions are formed? Except helium, all atoms of noble gases have 8 electrons in the outermost shell, i.e. an octet structure of electrons in the outermost shell.
It is believed that noble gases are unreactive because their electronic structures are very stable.
Atoms of elements other than noble gases do not have such stable electronic arrangements. They can become stable by gaining or losing electron(s) to attain the nearest noble gas structure.
10. Positive ions (Cations) Metal atoms lose their outermost shell electron(s) to form positive ions.
11. Positive ions (Cations)
12. Negative ions (Anions) Non-metal atoms gain electron(s) until there are eight electrons in the outermost shell to form negative ions (except hydrogen).
13. Negative ions (Anions)
14. What is an ionic bond? An ionic bond is the strong electrostatic attractive force between cations (+ve) and anions (-ve).
A complete transfer of electrons from a metal atom to a non-metal atom can form an ionic bond.
15. What is an ionic bond? Example: Magnesium fluoride
16. What is an ionic bond? What is a simple ion?
17. NAMES AND FORMULAE OF COMMON IONS
18. NAMES AND FORMULAE OF COMMON IONS
19. Formulae and naming of ionic compounds How can the formulae of an ionic compound be accurately predicted?
20. Formulae and naming of ionic compounds Examples:
21. Formulae and naming of ionic compounds Examples:
22. Formulae and naming of ionic compounds Examples: Mg(OH)2
23. Some more about formulae of ionic compounds: Suppose that the compound is made up of the cation Mm+ and the anion Aa-.
The formula of the compound is MaAm (simplify a and m if necessary). As examples,
24. Names of ionic compounds Name the cation first, then name the anion.
25. Names of ionic compounds Most anions have names ending in -ide, -ate or -ite.
26. Names of ionic compounds -ate and –ite stand for anions with more than one atom in the ion (e.g., sulphate, sulphite, nitrate, nitrite).
27. COVALENT BONDING How and why are covalent bonds (covalent molecules) formed?
28. COVALENT BONDING In the example below, each atomic nucleus (positively charged) has an attraction for the shared electron pair (negatively charged). Therefore, the two atoms are held firmly together.
29. COVALENT BONDING In the example below, each atomic nucleus (positively charged) has an attraction for the shared electron pair (negatively charged). Therefore, the two atoms are held firmly together.
30. COVALENT BONDING What is a molecule?
31. Examples for formation of covalent bond: The chlorine molecule
32. Examples for formation of covalent bond: The chlorine molecule
33. Examples for formation of covalent bond: The oxygen molecule
34. Examples for formation of covalent bond: The oxygen molecule
35. Examples for formation of covalent bond: The nitrogen molecule
36. Examples for formation of covalent bond: The nitrogen molecule
37. Examples for formation of covalent bond: The water molecules, H2O
38. Examples for formation of covalent bond: The water molecules, H2O
39. Examples for formation of covalent bond: The CH4 and NH3 molecules
40. Chapter 12 Chemical Bonding
41. Chapter 13 Chemical Equations
42. Chemical Equations
43. Chemical Equations
44. Chemical Equations
53. Chemical Equations
54. Chemical Equations
55. Chemical Equations
57. Chemical Equations
58. Examples – balance the following equations:
59. Examples – balance the following equations:
62. Chapter 13 Chemical Equations