Chemical Bonding12

1. Chemical Bonding12

2. Noble Gas Configuration • Elements will gain or lose electrons to obtain a noble gas configuration (full outer shell). • Metals tend to lose electrons • Nonmetals tend to gain electrons Current Electron Configuration 2-8-8-1 After losing an electron Nobel gas configuration 2-8-8

3. Energetically Stable • By achieving the noble gas configuration, the atom becomes more energetically stable (reaches a lower energy state). e-

4. Practice • How many electrons does fluorine what to gain or lose? • How many electrons would strontium like to gain or lose?

5. Gaining or Losing Electrons • When an electron is gained or lost, it isn’t being pulled out of air or released into space. • Electrons are always taken from or given to other atoms.

6. Bonding • When electrons are transferred, shared or pooled between atoms, a bond is formed. • A bond represents increased stability between two atoms.

7. Spectrum of Bonding There are many different types of bonding. Ionic Bonding CovalentBonding Electron Transferred Electron Attracted Electron Shared MetallicBonding IntermolecularBonding

8. Types of Bonding • Ionic Bonding: when electrons are transferred between atoms (Metal and Nonmetal) • Metallic Bonding: when electrons are pooled among atoms (all Metal) • Covalent Bonding: when electrons are shared between two atoms (all Nonmetals) • Intermolecular bonding: When an atom is attracted to electrons in another molecule (between covalent molecules)

9. Ionic Bonding • In ionic bonding, the electron is completely transferred from one atom to another. • Both atoms become charged ions. - + Na Cl

10. - Ionic Bonding Cl + 2 Mg - Cl

11. Ionic Formulas • Formulas represent the number of ions that are involved in bonding. • In the formula MgCl2, one magnesium atom is ionically bonded with two atoms of chlorine. • In the formula NaCl, one sodium atom is ionically bonded with one atom of chlorine.

12. Formula Writing When writing formulas for ionic systems, always write the cation (positively charged ion) first. MgCl2 Cl2Mg

13. Nature of ionic Bonds • Charged atoms are attracted to opposite charges much like magnets are. • However, nothing more is holding the atoms together. + -

14. Formula Units • Since no ion is specifically bonded with another ion, we cannot refer to ionic compounds as molecules. • Instead, we refer to ionic compounds as formula units (the ratio of cations to anions in the solid).

15. Writing Ionic Compound Formulas • Na and F K and P • Ca and O Mg and Cl

16. Writing Ionic Compound Formulas

17. Binary Compounds • For ionic compounds consisting of two types of atoms… NaCl The anion is given the element name ending in -ide The cation is given the element name Sodium Chloride

18. Common Anions • Sulfur = Sulfide • Oxygen = Oxide • Phosphorus = Phosphide • Nitrogen = Nitride • Fluorine = Fluoride • Chlorine = Chloride • Carbon = Carbide • Arsenic = Arsenide • Sellenium = Selenide • Bromine = Bromide • Iodine = Iodide

19. What is the formula for Sodium Phosphide?

20. You try one… What is the formula for Magnesium Oxide?

21. Polyatomic Ions • Some ions are composed of multiple atoms covalently bonded together • These groups of ions are called polyatomic ions [OH]- Hydroxide

22. Polyatomic Ions can be found on Table E

23. What is the formula for Sodium Hydrogen Carbonate? • Hint: Look on Table E

24. Ions with multiple charge states • Some elements have multiple charge states possible. • To designate the charge of these ions in the formula name, we use roman numerals.

25. Roman Numerals • 1 = I • 2 = II • 3 = III • 4 = IV • 5 = V • 6 = VI

26. Examples Consider the following name: Copper (II) Chloride

27. Practice Consider the following name: Chromium (VI) Oxide

28. Writing Ionic Compounds Iron (II) Oxide

29. Writing Ionic Compounds Vanadium (V) Bromide

30. Writing Ionic Compounds Beryllium Oxide

31. Writing Ionic Compounds Sodium Phosphate

32. Writing Ionic Compounds Iron (II) Cyanide

33. Writing Ionic Compounds Potassium Hydroxide

34. Writing chemical Names

35. For Binary Compounds • Write the name of the cation (first element) • Check the periodic table • If you look on the periodic table and the element has more than one charge, undo the criss-cross to determine the charges of the elements

36. Double check that the negative charge is correct, if not multiply BOTH charges by whatever number you need to have the correct negative charge (this means we simplified the first time round) • Use a Roman Numeral to represent the charge of the first element

37. Name the anion (second element). • Change the ending of the name to end in “ide”

38. What is the name for NaP?

39. What is the name for Fe2O3?

40. What is the name for MnO?

41. Polyatomic Compounds • Identify the polyatomic ion using Table E • Keep the name the same for the polyatomic ion and use the above naming rules for the other ion

42. What is the name for NH4Cl?

43. What is the name for NaOH?

44. What is the name for KClO3?

45. Covalent Bonding http://www.chemistrydaily.com/chemistry/Double_bond

46. Shared Electrons Covalent bonds are about sharing electrons. *Also called molecular bonds*

47. Shared Electrons • Atoms share electrons to have access to electrons to achieve a noble gas configuration. • Neither atom wants to lose its electrons. • They engage in a “tug of war” over the electrons. F e- H

48. Drawing Bonds • When two electrons are shared between two atoms, this bond is represented as a line. Hydrogen wants to gain 1 Fluorine wants to gain 1 e- e- F e- e- e- H e- e- e-

49. Non-bonding Electrons Electrons not involved in bonding are referred to as Lone Pairs of Electrons F H

50. Drawing Covalent Molecules • Drawing covalent molecules are a bit more complicated than ionic formula units. • Atoms are now bonded to specific atoms within the system. • We can represent these bonded systems through Lewis Dot Diagrams.