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Bonding and Chemical Reactions Chapters 6 and 7. Compounds and Molecules Chemical structure: the arrangement of atoms in a substance Chemical Bond: forces.

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Presentation on theme: "Bonding and Chemical Reactions Chapters 6 and 7. Compounds and Molecules Chemical structure: the arrangement of atoms in a substance Chemical Bond: forces."— Presentation transcript:

1 Bonding and Chemical Reactions Chapters 6 and 7

2 Compounds and Molecules Chemical structure: the arrangement of atoms in a substance Chemical Bond: forces that hold atoms together in a compound

3 Bond Models bond length: models distance between nucleus of 2 atoms bond angle: models angle the bonds between 3 or more atoms form space-filling: shows space that atoms take up bond angle space-filling

4 Nature of Bonds Some bonds are stronger than others, but all bonds can: bend stretch rotate without breaking

5 Chemical Structure and Properties compounds with networks are strong solids ex: diamond, quartz, many rocks networked compounds have melting and boiling points ex: salts, rocks, diamonds

6 Chemical Structure and Properties (cont’d) Some compounds are made of bonded ions ex. NaCl (strong attraction between ions) Some compounds are made of molecules ex: H 2, O 2, N 2, CO 2 (gases with weak attraction for each other) Hydrogen bonds are very strong

7 Bonding Atoms bond to gain 8 valence electrons- stable electronic configuration 2 basic types of bonding: -ionic -covalent

8 Ionic Bonding Ionic Bonds: between oppositely charged atoms; usually on opposite sides of the periodic table (metal and nonmetal) transfer electrons form networks, not molecules conduct electricity when dissolved LithiumFlourine

9 Covalent Bonds Covalent Bonds: share electrons; usually between 2 elements close on the periodic table (nonmetals) nonpolar covalent bond: e- shared equally polar covalent bond: e- shared unequally

10 Metallic Bonding “sea of electrons”: electrons can “float” freely between atoms; allows metals to conduct electricity well

11 Polyatomic Ions Compounds with both ionic and covalent bonds acts as a single unit (like ions) parentheses group polyatomic ion in a compound most names end in “ite” or “ate” (depending on # of oxygen atoms)

12 Compound Names and Formulas (Compounds have specific names so you can tell how many and what atoms are in the compound/moleule)

13 Ionic Naming Cations: the name of the element Anions: have “ide” at the end of the element’s name Ionic compounds must have a total charge of zero Sodium Chloride Cation is ALWAYS FIRST Anion is ALWAYS LAST Na +1 + Cl -1 = NaCl (0 charge)

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15 Transition Metal Naming Transition metals show their charges as Roman numerals because they can change charge FeO = Fe +2 + O -2 Iron (II) Oxide Fe 2 O 3 = Fe +3 + O -2 Iron (III) Oxide

16 What is the formula for Lithium oxide? Li- ____ O- ____ formula: _______________________

17 What is the name for CuCl 2 ? cation- ___________ anion- ___________, ending- __________ name- _____________________________

18 Covalent Naming To name covalent compounds, put a numerical prefix in front of the element’s name: 1- mono 6- hexa 2- di 7- hepta 3- tri 8- octa 4- tetra 9- nona 5- penta 10-deca If only 1 cation is present, no prefix is needed Atom to the right of the first cation ends in “ide”

19 What is the name of H 2 O? _______________________

20 Formulas Empirical Formula: smallest whole-number ratio of atoms in a compound Molecular Formula: how many atoms are in a molecule of a compound GLUCOSE C 6 H 12 O 6 CH 2 O Empirical Formula Molecular Formula

21 Organic and Biochemical Compounds Organic compound: covalently bonded compound that contains carbon Polymer: large molecule formed by more than 5 monomers (small units) ex. DNA

22 Chemical Reactions 1. Result in rearranged atoms 2. Involve changes in energy Exothermic: release energy (heat, fire, fizz, etc) Endothermic: absorb energy (drop in temp.) -remember, chemical energy is stored in chemical bonds

23 Endothermic ReactionExothermic Reaction

24 Chemical Equations Describing Coefficients: individual atom = “atom” 2Mg  2 atoms of magnesium covalent substance = “molecule” 3CO 2  3 molecules of carbon dioxide ionic substance = “unit” 4MgO  4 units of magnesium oxide

25 Chemical Equations (cont’d)

26 Balancing Steps 1. Write the unbalanced equation. 2. Count atoms on each side. 3. Add coefficients to make #s equal. Coefficient  subscript = # atoms 4. Reduce coefficients to lowest possible ratio, if necessary. 5. Double check atom balance!!!

27   2 3  6   6  Al + CuCl 2  Cu + AlCl 3 Al Cu Cl Balancing Example Aluminum and copper(II) chloride form copper and aluminum chloride.

28 Chemical Equations ___ CH 4 + ___ O 2 ___ CO 2 + ___ H 2 O methane and oxygen yield carbon dioxide and water Reactants Products

29 Balance the Reaction. ___ Mg + ___ O 2 ___MgO

30 Balance the reaction. ___ H 2 O 2 ___H 2 O + ___ O 2

31 Reaction Types Synthesis: combines substances A + B AB Decomposition: substances are broken apart AB A Combustion: ALWAYS has O₂ as a reactant AB + O₂ AO + BO

32 Reaction Types Single-Replacement (single-displacement): one element takes the place of another AX + B A + BX Double-Replacement (double-displacement): two compounds appear to exchange ions AX + BY AY + BX


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