Compounds. Part 1: Types of Compounds & Bonding

Transcription

1 Compounds Part 1: Types of Compounds & Bonding

2 Review In their natural state, atoms have no overall charge. 18 Ar Argon 40 Protons = 18 Electrons = 18 This is because the number of protons (+) equals the number of electrons (-).

3 Review Electrons are found in shells around the nucleus. 18 Ar Argon 40 Shell 1 = 2 e - Shell 2 = 8 e - Shell 3 = 8 e - * Each shell holds a certain number of electrons. * For elements 1-20 only

4 Review Elements link together to form compounds. A compound is formed when two or more different elements bond together. hydrogen atom H O oxygen atom hydrogen atom H

5 Review Elements link together to form compounds. A compound is formed when two or more different elements bond together. H O H water molecule

6 Why Compounds Form Some elements never form compounds! 2 He Helium 4 8 Ne Neon Ar Argon 40 Elements of the Noble Gases are unreactive. Why?

7 Why Compounds Form Some elements never form compounds! He Ne Ar To understand why, we must look at the number of electrons in their outer shells.

8 Why Compounds Form A full outer shell makes atoms very stable. He Ne Ar 2 e - 8 e - 8 e - Full shell Full shell Full shell

9 Why Compounds Form All other atoms do NOT have a full outer shell! Compounds form because atoms want to achieve a full outer shell of electrons. Atoms can do this in one of two ways: Gaining Ionic or Losing Compounds Electrons Covalent Sharing Compounds Electrons

10 Ionic Compounds Some atoms gain or lose electrons to get a full shell. An ion When is an they atom do with this, a they (+) form (-) ions. charge. + ion - ion

11 Ionic Compounds Some atoms gain or lose electrons to get a full shell. An ion When is an they atom do with this, a they (+) form (-) ions. charge. Full + ion shell! Full - ion shell!

12 Ionic Compounds Some atoms gain or lose electrons to get a full shell. An ion When is an they atom do with this, a they (+) form (-) ions. charge. Na +1 Cl -1 Sodium chloride

13 Ionic Compounds Ionic compounds are held together by ionic bonds. An An ion When ionic is an they bond atom do forms with this, a they as (+) a result form (-) ions. of charge. the attraction between (+) and (-) ions. Metals Lose e - Nonmetals Gain e - Ionic compounds always form between a metal and a nonmetal.

14 Another Example Mg reacts with F to form an ionic compound. Full Shell F -1 Mg Full +2 Shell 2 e - Full Shell F -1

15 Other Ionic Compounds Fertilizer (K 3 N) Toothpaste fluoride (NaF) White M&M logo (TiO 2 ) Bone minerals (CaO)

16 Review First! Most atoms do NOT have a full outer shell. Compounds form because atoms want to achieve a full outer shell of electrons. Atoms can do this in one of two ways: Gaining Ionic or Losing Compounds Electrons Covalent Sharing Compounds Electrons

17 Review First! Ionic compounds form between metals & nonmetals. Metals will LOSE electrons. Nonmetals will GAIN electrons. Metals lose e - since they have less than 4 electrons in their outer shells. Nonmetals gain e - since they have 4 or more electrons in their outer shells.

18 Covalent Compounds Covalent compounds form between nonmetals. Since nonmetals do NOT like to lose electrons, they share them instead. covalent bond Full Shell Full Shell Full Shell

19 Covalent Bonds Covalent compounds require covalent bonds. A covalent bond forms when two atoms share a pair of electrons. Atoms can share more than one pair of electrons: Double Two Pairs Bond Triple Three Bond Pairs

20 Covalent Bonds Covalent compounds require covalent bonds. Full Shell Full Shell Full Shell 6 e - 4 e - 6 e - carbon dioxide

21 Other Covalent Compounds Methane (CH 4 ) Hydrochloric acid (HCl) Rubbing alcohol (C 3 H 8 O) Glucose (C 6 H 12 O 6 )

22 Any Questions?

23 Compounds Part 2: Naming Compounds

24 1. Binary Compounds Naming binary compounds involves simple rules. The name of the first element (usually a metal) stays the same. Change the name of second element (usually a nonmetal) so that it ends in -ide NaCl sodium chlorine chloride

25 Practice Questions LiCl lithium chloride MgS magnesium sulfide FeP iron phosphide

26 2. Compounds With Many Atoms Other compounds have more than two elements. The name of the first element (usually a metal) stays the same. You must add a prefix in front of the 2nd element when there is more than one atom. TiO 2 titanium dioxide

27 Prefixes mono one penta five di two hexa six tri three hepta seven tetra four octa eight

28 Practice Questions CaCl 2 calcium dichloride BeF 3 beryllium trifluoride CCl 4 carbon tetrachloride

29 3. Compounds With Polyatomic Ions Some compounds have feature groups of atoms that stay together and act as a single unit. These groups are called polyatomic ions. (meaning: many atoms and charged) For example

30 Groups of Elements -CO 3 carbonate CO 3

31 3. Compounds With Polyatomic Ions Some compounds have feature groups of atoms that stay together and act as a single unit. These groups are called polyatomic ions. (meaning: many atoms and charged) For example When naming compounds with a polyatomic ion group, use its unique name at the end.

32 Groups of Elements MgCO 3 Mg CO 3 magnesium carbonate

33 Groups of Elements -CO 3 carbonate - SO 4 sulfate -PO 4 phosphate -NO 3 nitrate -HCO 3 bicarbonate -OH hydroxide

34 Practice Questions CaPO 4 calcium phosphate NaSO 4 sodium sulfate KOH potassium hydroxide

35 Any Questions?