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 Cl2, H2O, CH4, HCl. • Draw dot-and-cross diagrams to represent the multiple bonding in N2, C2H4 & CO2

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

5. (H) Draw dot and cross diagrams for the following molecules and check your answers with the following slides (right click to zoom) N2, C2H4 N2, C2H4 N2 C2H4

6. Atom Molecule Formula O O O N N N H H H P P P P P 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. O2 N2 H2 P4

7. Name Formula Methane H H C H H Carbon dioxide O O C Water H O H The formula of molecular compounds • Molecular compounds have formulae that show the type and number of atoms that they are made up from. CH4 CO2 H2O

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 • Write down the formula that contains 4 elements. • Write down the formula that is made up of 5 atoms. • Write down the formula that is a hydrocarbon. • Write down the formula that is made up of two elements and two atoms in total

16. Basic ideas- match up

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

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. - Figure 1 Figure 2 F F X X F F Covalent bonds • Covalent compounds are held together by this sharing of electrons. • 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).

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

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 Cl2, H2O, CH4, HCl. • Draw dot-and-cross diagrams to represent the multiple bonding in N2, C2H4 & CO2

29. HCl. • Cl2 • H2O, • CH4 • N2 • C2H4 • CO2

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

33. Basic ideas • Elements are chemically joined to make compound • The connection between the atoms in a compound is called a chemical bond • There are two types of this: covalent bonding and ionic bonding • The type of chemical bonding between metals and non-metals is ionic and the type of chemical bonding between non-metals is covalent • 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. - Figure 1 Figure 2 F F X X F F Covalent bonds • Covalent compounds are held together by this sharing of electrons. • 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).

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

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

39. H H (1) (1) H (2) Covalent bonding in hydrogen – H2 Hydrogen (1) needs 1 more electron to attain a full outer shell. H-H H (2)

40. Cl Cl Cl (2,8,7) (2,8,7) Cl (2,8,8) (2,8,8) Covalent bonding in chlorine Cl2 Chlorine (2.8.7) needs 1 more electron to attain a full electron shell. Cl-Cl

41. H H H H H H H H C C 4 • How many does carbon (2,4) need? 4 • How many hydrogens per 1 carbon? • Hydrogen (1) needs 1 more electron. • Draw bonding diagrams for methane – CH4.

42. Covalent bonding in Carbon dioxide – CO2 Carbon needs 4 more electrons but oxygen (2.6) needs 2 more. Therefore, we need 2 oxygen's. O C O 4 electrons: Double covalent bond 4 electrons: Double covalent bond Represented as = O C O

43. O O H H H H H H O Covalent bonding in water – H2O Hydrogen (1) needs 1 more electron but oxygen (2.6) needs 2 more. Therefore, we need 2 hydrogen's.

44. Cl-Cl O=O N=N Double bond Triple bond Single bond 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.

45. Task • Can you draw a dot and cross diagram for Oxygen • Nitrogen • Ethene C2H4 • HCl

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

47. N=N N N N N Nitrogen (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

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. Draw ‘dot and cross’ type bonding diagrams for each of the following: H H F H O C O C C H H S H H H H • Hydrogen fluoride (HF) • Hydrogen sulphide (H2S) • Ethane (C2H6 and the carbons are joined by a single covalent bond) • Carbon dioxide (CO2 and the carbon oxygen bonds are double bonds)