1. C3 Atoms, elements & compounds 3.5: Molecules & Covalent bonds 3.6: Giant Structures Req-giant structure

2. 3.5: Learning Objectives State that non-metallic elements form non- ionic compounds using a different type of bonding called covalent bonding. Describe the differences in volatility, solubility and electrical conductivity between ionic & covalent compounds. (H/W)

3. 3.5: Learning Objectives Supplement: Draw dot-and-cross diagrams to represent the sharing of electron pairs to form single covalent bonds in simple molecules, exemplified by Cl 2, H 2 O, CH 4, HCl. Draw dot-and-cross diagrams to represent the multiple bonding in N 2, C 2 H 4 & CO 2

4. Covalent bonding in hydrogen chloride Both hydrogen (1) and chlorine (2.8.7) needs 1 more electron to attain a full outer shell. H (2) Cl (2,8,8) H-Cl Cl (2,8,7) H (1)

5. (H) Draw dot and cross diagrams for the following molecules and check your answers with the following slides (right click to zoom) N 2, C 2 H 4 N 2 C 2 H 4

6. Chemical formula of elements Each element has a symbol. Some elements exist as particular numbers of atoms bonded together. This fact can be represented in a formula with a number which shows how many atoms. O N H H H P N N FormulaMoleculeAtom O O P P P P O2O2 N2N2 H2H2 P4P4

7. The formula of molecular compounds Water Carbon dioxide Methane FormulaName C H H H H C O O H H O Molecular compounds have formulae that show the type and number of atoms that they are made up from. CH 4 CO 2 H2OH2O

8. 1. Octane The molecular formula of this compound: The number of different elements present in this compound: Names of each element and how many atoms of each element:

9. 2. Propane The molecular formula of this compound: The number of different elements present in this compound: Names of each element and how many atoms of each element:

10. 3. Ethanoic acid The molecular formula of this compound: The number of different elements present in this compound: Names of each element and how many atoms of each element:

11. 4. Hydrogen peroxide The molecular formula of this compound: The number of different elements present in this compound: Names of each element and how many atoms of each element:

12. 4. Ethene The molecular formula of this compound: The number of different elements present in this compound: Names of each element and how many atoms of each element:

13. 5. Methanol The molecular formula of this compound: The number of different elements present in this compound: Names of each element and how many atoms of each element:

14. 4.1

15. 20.08.12 Bonding Answer the questions below 1.Write down the formula that contains 4 elements. 2.Write down the formula that is made up of 5 atoms. 3.Write down the formula that is a hydrocarbon. 4.Write down the formula that is made up of two elements and two atoms in total

16. Basic ideas- match up Atom Ion Molecule H2OH2O Na + He

17. 3. Ethanoic acid The molecular formula of this compound: The number of different elements present in this compound: Names of each element and how many atoms of each element:

18. 4. Hydrogen peroxide The molecular formula of this compound: The number of different elements present in this compound: Names of each element and how many atoms of each element:

19. 4. Ethene The molecular formula of this compound: The number of different elements present in this compound: Names of each element and how many atoms of each element:

20. 5. Methanol The molecular formula of this compound: The number of different elements present in this compound: Names of each element and how many atoms of each element:

21. C3: Covalent bonding Non-metals combine together by sharing electrons and this is called covalent bonding

22. How is HCl bonded? HCl

23. Covalent bonding in hydrogen chloride Both hydrogen (1) and chlorine (2.8.7) needs 1 more electron to attain a full outer shell. H (2) Cl (2,8,8) H-Cl Cl (2,8,7) H (1)

24. Covalent compounds Covalent compounds are formed when non-metal atoms react together. As these atoms come near their outer electrons are attracted to the nucleus of both atoms and become shared by the atoms. The shared electrons count towards the shells of both atoms and therefore help fill up incomplete electron shells. (Duplet 2 ) (Octet 8)

25. Covalent bonds Covalent compounds are held together by this sharing of electrons. covalent bond.A pair of electrons shared in this way is known as a covalent bond. It is sometimes represented in full bonding diagrams (see figure 1). Often these bonds are just shown as a pair of electrons (xx) or even just a line (see figure 2). F XXXX F F F - Figure 1Figure 2

26. Covalent bonding in hydrogen chloride Both hydrogen (1) and chlorine (2.8.7) needs 1 more electron to attain a full outer shell. H (2) Cl (2,8,8) H-Cl Cl (2,8,7) H (1)

27. (H) Draw dot and cross diagrams for the following molecules and check your answers with the following slides (right click to zoom)

28. 3.5: Learning Objectives Supplement: Draw dot-and-cross diagrams to represent the sharing of electron pairs to form single covalent bonds in simple molecules, exemplified by Cl 2, H 2 O, CH 4, HCl. Draw dot-and-cross diagrams to represent the multiple bonding in N 2, C 2 H 4 & CO 2

29. HCl. Cl 2 H 2 O, CH 4 N 2 C 2 H 4 CO 2

30. Ionic & covalent bonding When an atom of a metal joins with an atom of a non-metal an ionic bond is formed. When 2 non-metals combine they share electrons to form a covalent bond. The atoms join to form a molecule.

31. Covalent Bonding This involves electrons being shared Full outer shells are formed. Resulting in a stable structure Covalent bonds are made between atoms of non-metals Examples of molecules with covalent bonds include: Water and Carbon dioxide

32. Basic ideas 1.Elements are chemically joined to make ………….. 2.The connection between the atoms in a compound is called a …………….. bond 3.There are two types of this: ……………… bonding and...………… bonding 4.The type of chemical bonding between metals and non-metals is ……………. and the type of chemical bonding between non-metals is ………………… 5.A substance that is made of two or more atoms bonded together is called a m……………..

33. Basic ideas 1.Elements are chemically joined to make compound 2.The connection between the atoms in a compound is called a chemical bond 3.There are two types of this: covalent bonding and ionic bonding 4.The type of chemical bonding between metals and non-metals is ionic and the type of chemical bonding between non-metals is covalent 5.A substance that is made of two or more atoms bonded together is called a molecule

34. C3: Covalent bonding Non-metals combine together by sharing electrons and this is called covalent bonding

35. Covalent compounds Covalent compounds are formed when non-metal atoms react together. As these atoms come near their outer electrons are attracted to the nucleus of both atoms and become shared by the atoms. The shared electrons count towards the shells of both atoms and therefore help fill up incomplete electron shells. (Duplet 2 ) (Octet 8)

36. Covalent bonds Covalent compounds are held together by this sharing of electrons. covalent bond.A pair of electrons shared in this way is known as a covalent bond. It is sometimes represented in full bonding diagrams (see figure 1). Often these bonds are just shown as a pair of electrons (xx) or even just a line (see figure 2). F XXXX F F F - Figure 1Figure 2

37. Covalent bonding in hydrogen chloride Both hydrogen (1) and chlorine (2.8.7) needs 1 more electron to attain a full outer shell. H (2) Cl (2,8,8) H-Cl Cl (2,8,7) H (1)

38. (H) Draw dot and cross diagrams for the following molecules and check your answers with the following slides (right click to zoom)

39. Covalent bonding in hydrogen – H 2 Hydrogen (1) needs 1 more electron to attain a full outer shell. H (2) H-H H (1) H H (2)

40. Covalent bonding in chlorine Cl 2 Chlorine (2.8.7) needs 1 more electron to attain a full electron shell. Cl (2,8,7) Cl ( 2,8,7 ) Cl (2,8,8) Cl (2,8,8) Cl-Cl

41. Hydrogen (1) needs 1 more electron. How many does carbon (2,4) need? How many hydrogens per 1 carbon? Draw bonding diagrams for methane – CH 4. 4 4 C H H H H C H H H H

42. C O O Represented as = COO Covalent bonding in Carbon dioxide – CO 2 Carbon needs 4 more electrons but oxygen (2.6) needs 2 more. Therefore, we need 2 oxygen's. 4 electrons: Double covalent bond

43. Covalent bonding in water – H 2 O Hydrogen (1) needs 1 more electron but oxygen (2.6) needs 2 more. Therefore, we need 2 hydrogen's. O H H O H H O H H

44. Covalent bonding - multiple bonds Mostly electrons are shared as pairs. There are some compounds where they are shared in fours or even sixes. This gives rise to single, double and triple covalent bonds. Again, each pair of electrons is often represented by a single line when doing simple diagrams of molecules. Cl-Cl Single bond O=O Double bond N=N Triple bond

45. Task Can you draw a dot and cross diagram for Oxygen Nitrogen Ethene C 2 H 4 HCl

46. Covalent bonding in oxygen Oxygen (2.8.6) needs 2 more electrons to attain a full electron shell. O O O=O O O 4 electrons

47. (Higher) Nitrogen (2.8.5) needs 3 more electrons to attain a full electron shell and forms a triple bond. Draw a bonding diagram of nitrogen. 6 electrons N N N N N=N Nitrogen

48. Supplement Ensure you can draw structures for the following: Remember the exam is not restricted to using only these! So practice and ensure you understand this! Chlorine Water Methane Hydrogen Chloride Nitrogen Ethene Carbon Dioxide

49. Covalent bonding animation sc_ocr_c3c2

50. 1.Hydrogen fluoride (HF) 2.Hydrogen sulphide (H 2 S) 3.Ethane (C 2 H 6 and the carbons are joined by a single covalent bond) 4.Carbon dioxide (CO 2 and the carbon oxygen bonds are double bonds) H F H H S H H H H H H CC CO O Draw ‘dot and cross’ type bonding diagrams for each of the following:

51. 3.6 GIANT STRUCTURES Learning objectives Supplement only: Describe the giant covalent structures of graphite & diamond. Relate their structures to the use of graphite as a lubricant and of diamond in cutting. Describe the structure of Silicon (IV) Oxide (Silicon dioxide)

52. Research Task Research the following: Structures of Diamond, Graphite & Silicon (IV) Oxide (Silicon Dioxide). Relate the structure to the use of Diamond & Graphite.

53. Small covalent structures Sometimes just a few atoms join together in this way. This produces small covalent molecules – often known as simple molecular structures. a simple molecular structure covalent bonds

54. Giant covalent structures Sometimes millions of atoms are joined together by covalent bonds. giant lattice.This produces a rigid 3-D network called a giant lattice. a giant lattice covalent bonds

55. Giant covalent structures: diamond One form of carbon is diamond. Each diamond consists of millions of carbon atoms bonded into a single giant structure. veryIt is very hard. Diamond strong covalent bonds carbon atoms

56. Giant covalent structures: graphite A more common form of carbon is graphite. Millions of carbon atoms are bonded into a giant structure but within this structure the layers are only weakly joined.

57. Giant covalent structures: carbon footballs! During the last 20 years new forms of carbon have been discovered some of which have “closed cage” arrangements of the atoms. These are large but are not really giant molecules. One of them contains 60 carbon atoms and bears remarkable similarities to a football!

58. Giant covalent structures: sand Sand is an impure form of silicon dioxide. Although it is a compound, it has a giant covalent structure with certain similarities to diamond.

59. BONDING AND PHYSICAL PROPERTIES

60. Metallic bonding Metal atoms form a giant lattice similar to ionic compounds. The outermost electrons on each metal are free to move throughout the structure and form a “sea of electrons”. Having released electrons into this “sea” the metal atoms are left with a + charge. = positively charged metal ion Metallic bonding is the attraction of + metal ions for the “sea of electrons.”

61. Bonding and physical properties These are things such as: Density Conductivity Malleability/ brittleness Melting point The type of structure that substances have has a huge effect upon physical properties. The next few slides illustrate just a few of the general patterns.

62. Bonding & physical properties HARDNESS, WHY? CONDUCT ELECTRICITY MELTING POINT /BOILING POINT DISSOLVE IONIC GIANT COVALENT SIMPLE COVALENT METALLIC

63. Simple covalent compounds Carbon dioxide and water are simple covalent molecules

64. Carbon dioxide does not conduct electricity Unlike ions, Carbon dioxide does not have a charge or free electrons and so does not conduct electricity C O O Covalent bonds

65. Water does not conduct electricity Unlike ions, Water does not have a charge or free electrons and so does not conduct electricity

66. Intermolecular forces in CO 2 and H 2 O Carbon dioxide and water have weak intermolecular forces between molecules. Understanding this can help explain the properties of CO 2 and H 2 O

67. Intermolecular Forces First we must learn about intermolecular forces: Intermolecular forces are forces which act between whole molecules Look at the following slides

68. Intermolecular forces between Water molecules

69. Intermolecular forces between hydrocarbon molecules

70. Carbon dioxide is a molecule: It has LOW MELTING &…. BOILING POINT. (that’s why it’s a gas) This is because of the WEAK forces of attraction BETWEEN the molecules – WEAK INTERMOLECULAR BONDS CO 2

71. Carbon dioxide – CO 2 – is a GAS at room temperature, with a low M.P, this is due to weak intermolecular bonds. Water – H 2 O – is a LIQUID at room temperature, with a low M.P, this is due to weak intermolecular bonds, BUT stronger than CO 2. CO 2 H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O

72. Relating the properties of carbon dioxide and water to their structure The weak intermolecular forces in CO 2 and H 2 O mean these simple molecules have low melting points There are no free electrons so both do not conduct electricity.

73. Generally substances with giant structures have high melting points and boiling points. Small molecules have melting points and boiling points that increase as the size of the molecule increases. + - + - + - - ++ + - + - -- - + + + - + - + - - ++ In giant structures all the atoms are tightly bonded together. Usually they are high melting-point solids. Small molecules tend to be gas, liquid solids with low melting points. weak forces between molecules Bonding and physical properties

74. Ionic compounds are very brittle. Opposite charges attract, so neighbouring ions are pulled together. When something hits the substance a layer of ions will be pushed so that they are next to ions with the same charge. Attraction becomes: + - + - + - - ++ + - + - -- - + + + - + - + - - ++ + - + - + - - ++ Blow + - + - + - - ++ repulsion! Bonding and physical properties

75. Metals are not brittle. The metal atoms are the same and exist in simple structures. If something hits the substance, it simply moves to the next layer along. Blow Bonding and physical properties

76. Covalent substances do not conduct electricity. This is because in covalent substances the outer electrons are fixed (localised) between specific atoms. Metals conduct electricity. In metals the electrons can, given a potential, move anywhere throughout the structure. H H H H H H CC electrons fixed in covalent bonds electrons free to move Bonding and physical properties

77. Ionic substances do not conduct electricity as solids. When molten or dissolved they will conduct (and also undergo electrolysis). This is because the electricity is carried through the solution by the ions which are free to move when the ionic compound is molten or in solution. + - + - + - - ++ + - + - -- - + + + - + - + - - ++ Solid – not free to move Doesn’t conduct - + + - + - Molten – mobile Does conduct Bonding and physical properties

78. Generally substances with giant structures do not dissolve easily (although many ionic compounds dissolve in water for a special reason). Again this is because in giant structures separating the particles involves breaking chemical bonds. Small molecules usually dissolve in a range of solvents. We just separate one molecule from another. weak forces between molecules + - + - + - - ++ + - + - -- - + + + - + - + - - ++ Giant structures generally don’t dissolve easily. strong bonds between the atoms/ions Bonding and physical properties

79. Bonding & physical properties HARDNESS, WHY? CONDUCT ELECTRICITY MELTING POINT /BOILING POINT DISSOLVE IONIC BRITTLE WHEN molten or dissolved as electricity is carried through the solution by ions. Not when molten HIGH-due to strong electrostatic attraction between ions. DISSOLVE IN SOLVENTS LIKE WATER OR PETROL SIMPLE COVALENTUsually gas of liquid at room temperature. No-electrons are fixed between atoms. Increase with size. Water unusual has high mp & bp for a small covalent molecule. Dissolve in some solvents GIANT COVALENTHARD NO- as electrons are fixed between atoms HIGHDO NOT DISSOLVE EASILY-as it involves breaking chemical bonds METALLICNOT BRITTLEWHEN SOLID & LIQUID –as electrons can move freely. HighNo

80. (H) Find and explain … 1.Find these physical properties of water and carbon dioxide. – Melting points – Electrical conductivity (do they conduct electricity?) 2.Explain why some of the above have low melting points and others high? Use these ideas in your answer Intermolecular forces Freely moving electrons or ions Support sheet for foundation students Information sheet for higher students

81. Recap activites

82. Copy the Table and fill in the blank columns. Yes LowNoE Small or giant? Yes No Yes Conduct when molten NoHighNoD HighNoC LowYesB HighNoA Metal Ionic Small Mol Giant Mol Conduct as solid Melting Point Soluble in petrol GiantMetal SmallSmall Mol Giant Giant Mol Giant Ionic Substance E is peculiar: Can you suggest an actual substance that E could be? Can you explain the low melting point? Metal Giant Activity Substance

84. What type of bonding will the substances have? SubstanceBonding Brass (Alloy copper + zinc) Copper oxide Sulphur dioxide Iron Sodium fluoride Nitrogen chloride Metallic Ionic Covalent Metallic Ionic Covalent

85. Which of the following will have covalent bonding? A. Sodium chloride B. Iron C. Bronze D. Nitrogen dioxide

86. Which of the following will have metallic bonding? A. Copper chloride B. Graphite C. Bronze D. Phosphorus chloride

87. Which is a true statement about covalent bonds? A. Usually formed between metals and non- metals B. Involve transfer of electrons between atoms. C. Form full electron shells by sharing of electrons. D. Always involve 2 electrons per atom.

88. Which of the following exists as a giant molecular structure? A. Water B. Carbon dioxide C. Sodium chloride D. Diamond

89. What will be the formula of the compound formed by hydrogen and sulphur? A.HS B.H 2 S C.HS 2 D.H 2 S 2 32 S 16 1H11H1 1 2.8.6

90. Which of these will conduct as both solid and liquid? A. metal B. ionic C. small molecules D. giant molecules

91. Which of these will conduct when liquid but not when solid? A. small molecules B. giant molecules C. metal D. ionic

92. Which of these will dissolve in solvents like petrol? A. small molecules B. giant molecules C. metal D. ionic

93. Which of these will not conduct at all and is hard to melt? A. small molecules B. giant molecules C. metal D. ionic

94. HHe LiBeBCNOFNe NaMgAlSiPSClAr KCaFeNiCuZnBrKr AgIXe PtAuHg The Periodic Table Alkali metals Noble gases Halogens These elements are metals This line divides metals from non- metals These elements are non-metals

95. Electronic Structure

96. 17234568 Arrangement of Electrons 1 2 3 Click on action buttons to reveal how electron configuration is built-up. The transition metals Skip this

97. 3 2,8,12,8,22,8,32,8,42,8,52,8,62,8,72,8,8 17234568 Electrons in Period 3 Elements in the third period have complete first and second shells. The third shell is completed one electron at a time as you cross the period from left to right. Skip this

98. 17234568 1 Electrons in Period 1 1 2 Skip this

99. Electrons in Period 2 17234568 2 2,12,22,32,42,52,62,72,8 This atom is special it has a complete outer shell Elements in the second period contain 2 electrons in the first shell (complete) and the second shell is completed one electron at a time as you cross the period from left to right. Skip this

100. 3 2,8,12,8,22,8,32,8,42,8,52,8,62,8,72,8,8 17234568 Electrons in Period 3 Elements in the third period have complete first and second shells. The third shell is completed one electron at a time as you cross the period from left to right. Skip this

101. 1 1 2 3 1 2,1 2,8,1 Group 1 Elements Group 1 elements have 1 electron in the outermost shell which they lose in chemical reactions. The outer electron is further from the nucleus and so more easily lost as you go down the group. This is why reactivity increases going downwards Skip this

102. 2 2,2 2,8,2 Group 2 Elements In chemical reactions metals tend to lose their outer shell electrons to form positive ions. So, these elements all form ions with a 2+ charge. The further the outer shell is from the nucleus the more easily electrons are lost. CATIONS-form after loss of electron Anions-gain of electrons Skip this

103. 3 2,3 2,8,3 Group 3 Elements Metals lose their outer electrons to form ions. The charge on the ion produced by Group 3 metals will be +3. Skip this

104. 4 2,4 2,8,4 Group 4 Elements The elements at the top of Group 4 are non-metals. They bond covalently, i.e. by sharing electrons with another atom. Skip this

105. 5 2,5 2,8,5 Group 5 Elements The number of electrons in the outermost shell is the same as the group number. They need 3 more electrons to achieve a full electron shell. Skip this

106. 6 2,6 2,8,6 Group 6 Elements The atoms in Group 6 form negative ions (2-) by the addition of two extra electrons. This completes their outer most shell. Skip this

107. 7 2,7 2,8,7 Group 7 Elements Group 7 elements form 1- ions by the addition of 1 extra electron. They are most reactive at the top of the group because incoming electrons are pulled into shells that are closer to the nucleus. Skip this

108. 8 2,8 2,8,8 Group 0 Elements The elements in Group 8 (or 0) have complete outer shells. They are very unreactive and are called NOBLE (or inert) GASES. 2 Skip this

109. Mendeleev Periodic table Horizontal rows are called PERIODS Vertical columns are called GROUPS Hello. My name’s Dimitri Mendeleev. In the 19th century I arranged all the known elements into a pattern according to their properties. This pattern is called “The Periodic Table”

110. Columns of elements H Li Na K Rb Cs Fr Be Mg Ca Sr Ba Ra Ga In Tl Al B Ge Sn Pb Si C Sb Bi P N AsSe Te Po O S He Kr Ne Ar Rn Xe ScTiVCrMnFeCoNiCuZn YZrNbMoTcRuPdAgCdRh HfTaWReOsIrAuHgLaPt RfDbSgBhHsMt??Ac? Br At Cl F I What are columns of elements called? 765432 Groups 10 Group number transition elements

111. Rows of elements H He LiBeNOFNeBC NaMgAlPSClArSi KScTiVCrMnFeCoNiCuZnGaGeSeBrCaKrAs RbYZrNbMoTcRuPdAgCdInSnSbSrTeRhIXe CsBaHfTaWReOsIrAuHgTlPbBiPoLaAtPtRn FrRaRfDbSgBhHsMt??Ac? Periods What are rows of elements called? 1234567 Period number

112. Tasks Starter after finishing both bonding imp.doc Structure and bonding information sheet.doc Bonding_card_sort or info sheet.doc

113. Plenary C3c_self assess quiz.doc C3c_self assess answers.doc.

114. Don’t forget your homework! Describe the differences in volatility, solubility and electrical conductivity between ionic & covalent compounds. (H/W)