iONIC AND Covalent bonding of atoms.pptx

he difference between ionic and covalent bonds is how the electrons are used. In ionic bonding, one atom donates electrons to the other. In covalent bonding, the two atoms share electrons. Covalent bonds share electrons and ionic bonds donate electrons.

1. Chemical Bond

2. Na Cl C H O H O What is holding them together? What is holding them together? What is holding them together? Attractive Force Attractive Force Attractive Force

3. Chemical Bond The attraction between atoms, ions and molecules to form a chemical compound is called chemical bond .

4. Metals Non-metals

5. Valence Electron Valence comes from the Latin word valentia which means “ capacity ”. Valence refers to the capacity to form bonds. Valence electrons are the outermost electrons The electrons involved in the bond. e

6. Octet Rule Electron are transferred or shared in a way that each atom acquires a stable noble-gas configuration, which is an eight valence shell electron or an octet.

7. Electronegativity “ Electronegativity is the tendency of an atom to attract electrons.” Metal atoms have low electronegativity, meaning that they have little tendency to attract electrons. Nonmetal atoms have high electronegativity, which means they are able to attract electrons easily.

8. IONIC BONDING

9. Ionic Bond Is a chemical bond between cation and anion formed by an electrostatic attraction. Bond between metals and non-metals

10. Ions Positive ions are called Cations Negative ions are called Anions Cations ( + ) Anions ( - )

11. Electrostatic Attraction States that particles of opposite charge attracts

12. Cl e e e e e e e e e e e e e e e e e e

13. Sodium Chloride Cl e e e e e e e e e e e e e e e e e e

14. Na e e e e e e e e e e Sodium Chlorine Cl e e e e e e e e e e e e e e e e e +1 -1 e e

15. Noble Gases

16. Ca e e e e e e e e e e e e e e e e e e Ca Na e e e e e e e e O CaO (Calcium Oxide) e e

17. Ca e e e e e e e e e e e e e e e e e e Ca CaO (Calcium Oxide) Na e e e e e e e e O e e 2+ 2-

18. COVALENT BONDING

19. Covalent bonds Nonmetals hold onto their valence electrons. They can’t give away electrons to bond . Get it by sharing valence electrons with each other. By sharing both atoms get to count the electrons toward noble gas configuration.

20. Steps in Lewis diagram of Covalent Step 1 count total valence e - involved Step 2 connect the central atom (usually the first in the formula) to the others with single bonds Step 3 complete valence shells of outer atoms IF the central atom has 8 valence e - surrounding it . . YOU’RE DONE!

21. Draw the Lewis Dot Diagram for polyatomic ions Count all valence e- needed for covalent bonding Add or subtract other electrons based on the charge REMEMBER! A positive charge means it LOST electrons!!!!!

22. Application Write the Lewis diagram of the following Compound CCl 4 H 2 O HCl NH 3 H 2

23. Covalent bonding Q7 CCl 4 - Covalent C Cl Cl Cl Cl HCl - Covalent H Cl MgF 2 - Ionic [ F ] 2 – [Mg] 2+ H 2 O - Covalent H O H NH 3 - Covalent H N H H NaCl - Ionic [ Cl ] – [Na] + OH – - Covalent O H H 2 - Covalent H H For more lessons, visit www.chalkbored.com

24. POLAR AND NON-POLAR COVALENT BOND Non-polar Covalent Bond A bond between 2 nonmetal atoms that have the same electronegativity and therefore have equal sharing of the bonding electron pair Equal sharing of electron Polar Covalent Bond A bond between 2 nonmetal atoms that have different electronegativities and therefore have unequal sharing of the bonding electron pair Unequal sharing of electrons

25. Nonpolar Covalent Bond H 2 - Covalent H H In H-H each H atom has an electronegativity value of 2.1, therefore the covalent bond between them is considered nonpolar

26. Polar Covalent Bond In H-Cl, the electronegativity of the Cl atom is 3.0, while that of the H atom is 2.1 HCl - Covalent H Cl

27. ELECTRONEGATIVITY DIFFERENCE Ionic- Electronegativity is ≥ 1.7 Polar Covalent - Electronegativity is 1.7 EN >0.4 Nonpolar Covalent- Electronegativity is < 0.4

28. Some Compounds and the type of Chemical B onds Compound More electronegative atom Electronegativity Type of Chemical Bond NaCl Chlorine 3.0 - 0.9 = 2.1 Ionic ICl Chlorine 3.0 – 2.5 = 0.5 Polar Covalent H 2 None (same) 2.1 – 2.1= 0 Non-polar Covalent

29. Activity: Based on the metallic properties of elements, predict first if the bond between the pair of atoms is ionic, non-polar covalent and polar covalent. Then calculate the electronegativity difference between the atoms to further classify the bond. Determine the more electronegative atom in each pair: Compound More electronegative atom Electronegativity Type of Chemical Bond Cl and K Cl and C Cl and Cl O and Ca O and Cl O and O

30. MOLECULAR POLARITY

31. Polarity is a physical property of compounds which relates other physical properties such as melting and boiling points, solubility, and intermolecular interactions between molecules Polar molecules are soluble in water, while non-polar are not

32. Polarity Substances with similar polarities dissolve in each other Polar molecules are soluble in water, while non-polar are not Substances with very different polarities do not dissolve in each other

33. DETERMINING THE POLARITY OF MOLECULES Check the electronegativity of each element If the difference in electronegativity for the atoms in a bond is greater than 0.4, we consider the bond polar . If the difference in electronegativity is less than 0.4, the bond is nonpolar 36

34. ELECTRONEGATIVITY DIFFERENCE Ionic- Electronegativity is ≥ 2.0 Polar Covalent - Electronegativity EN >0.4 Nonpolar Covalent- Electronegativity is < 0.4

35. Sample: Find the type of bonds 1. NaCl 2. ICl 3. H 2

36. Some Compounds and the type of Chemical B onds Compound More electronegative atom Electronegativity Type of Chemical Bond NaCl Chlorine 3.0 - 0.9 = 2.1 Ionic ICl Chlorine 3.0 – 2.5 = 0.5 Polar Covalent H 2 None (same) 2.1 – 2.1= 0 Non-polar Covalent

37. Intermolecular Forces of Attraction

38. 41 Van Der Waals Forces These are intermolecular forces of attraction between neutral molecules. The Nobel Prize in Physics 1910 (Johannes van der Waals) "for his work on the equation of state for gases and liquids"

39. 42 intER vs. intRA molecular forces Intramolecular forces are the forces within a molecule or ionic compound NaCl Ionic bond between atom of Na and atom of Cl Intermolecular forces are the forces between molecules or ions and molecules Example: Solid liquid gas .

40. 43 3 Types of van der Waals Forces Dipole-Dipole forces London Dispersion forces Hydrogen bonding

41. 44 DIPOLE-DIPOLE FORCES These are forces of attraction that occur between polar molecules. (big difference in electron negativity) These forces are effective only when polar molecules are very close. As distance increase strength of bond decreases. For molecules of approximately equal mass and size, the strength of force of attraction increases as the polarity increases. Radius have an effect on strength of dipole.

42. 45 DIPOLE-DIPOLE FORCES + _ _ _ + + + _

43. 46 DIPOLE-DIPOLE FORCES Molecules with larger dipole moments have higher melting and boiling points (hard to break) than those with small dipole moments. Dipole attractions are relatively weak and tend to be liquids or gas at room temperature.

44. 47 HYDROGEN BONDING A special type of dipole-dipole interaction between the hydrogen atom in a polar bond and an unshared electron pair of an element that is very electronegative usually a F, O, or N atom on another molecule (note that all of these have very high EN’s and small atomic radii).

45. 48

46. 49 HYDROGEN BONDING These types of bonds are super-humanly strong. (4X stronger that dipole dipole)

47. 50 HYDROGEN BONDING IN WATER

48. 51 IMPORTANCE OF HYDROGEN BONDING Are important biologically, in stabilizing proteins and keeping DNA together. Also explains why ice is less dense than water (see text).

49. 52 LONDON DISPERSION FORCES Fritz London These are forces that arise as a result of temporary dipoles induced in the atoms or molecules.( it’s a temporary accident!) All molecules have some degree of LD forces

50. 53 LONDON DISPERSION FORCES LD forces occur between neutral non-polar molecules. (nobles gases and nonpolar compounds) LD forces are weak The greater the number of electrons the greater the LD force. ( ie the greater the melting and boiling pt.) LD force molecules have Low melting and boiling pts