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Bonding and Chemical Reactions

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Presentation on theme: "Bonding and Chemical Reactions"— 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: H2, O2, N2, CO2 (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 Lithium Flourine

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)


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 Fe2O3 = Fe+3 + O-2 Iron (III) Oxide

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

17 What is the name for CuCl2
What is the name for CuCl2? cation- ___________ anion- ___________, ending- __________ name- _____________________________

18 Covalent Naming To name covalent compounds, put a numerical prefix in front of the element’s name: 1- mono hexa 2- di hepta 3- tri octa 4- tetra nona 5- penta 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 H2O? _______________________

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 Molecular Formula Empirical Formula C6H12O6 CH2O

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 Result in rearranged atoms
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 Reaction Exothermic Reaction

24 Chemical Equations Describing Coefficients: individual atom = “atom”
2Mg  2 atoms of magnesium covalent substance = “molecule” 3CO2  3 molecules of carbon dioxide ionic substance = “unit” 4MgO  4 units of magnesium oxide

25 Chemical Equations (cont’d)

26 Coefficient  subscript = # atoms
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 Balancing Example Al + CuCl2  Cu + AlCl3 Al Cu Cl 3 2 2 3 2 2 3 3 2
Aluminum and copper(II) chloride form copper and aluminum chloride. Al CuCl2  Cu AlCl3 Al Cu Cl 2   2 3  6   6  3

28 Chemical Equations ___ CH4 + ___ O2 ___ CO2 + ___ H2O
methane and oxygen yield carbon dioxide and water ___ CH4 + ___ O ___ CO2 + ___ H2O Reactants Products

29 Balance the Reaction. ___ Mg + ___ O ___MgO

30 Balance the reaction. ___ H2O ___H2O + ___ O2

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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