Chapter 6    The Structure of Matter

 

Key Ideas:

1.  What holds a compound together? ______________________________________________________________________________

2.  How can the structure of chemical compounds be shown?     ______________________________ _________________________________

3.  What determines the properties of a compound? ______________________________________________________________________________

Key Terms:

·      Chemical bond

·      Chemical structure

·      Bond length

·      Bond angle

 

 

I.                Section 1 Compounds and Molecules

a.   Chemical Bonds-

                                                           i.      the forces that hold atoms or ions together in a compound.

                                                       ii.      An attractive force between one atoms protons and another atoms electrons.

 

b.  Chemical Structure- shows how atoms combine

                                                           i.      Some models represent bond lengths and angles

1.  bond lengths-is a distance from one nuclei to the other nuclei in a chemical compound.

2.  Bond angles- an angle created by the push and pull of electrons and protons in a group of bonded atoms.

                                                       ii.      Structural formulas show both the bond length and bond angle

c.   How does Structure affect properties?

                                                           i.      The chemical structure determines the properties of a compound

                                                       ii.      Compounds with network structures

1.  Properties

a.   Strong solid

b.  High melting point.

2.  examples

a.    Some covalent compounds/ silicon dioxide or quartz rock

b.  All ionic compounds/ Sodium chloride table salt

 

 

                                                   iii.      Some compounds are made of molecules

1.  Some covalent compounds

2.  Molecules are groups of atoms that can exist completely by themselves.

3.  Molecules properties

a.   Can be solids, liquids, are gases

b.  Has weak bonds

c.   Low melting point

 

 

Key Items:

4.  Why do atoms form bonds? _________________________________________________________

5.  How do ionic bonds form?________________________________________________________

6.  What do atoms joined by covalent bonds share?___________________

7.  What gives metals their distinctive properties?____________________

8.  How are polyatomic ions similar to other ions?___________________________________

Key Terms:

·      Ionic Bond

·      Covalent Bond

·      Metallic Bond

·      Polyatomic Bond

 

II.            (Section 2)  Ionic and Covalent Bonding

a.   Why do chemical bonds form?

                                                           i.      Atoms form bond to become stable

1.  Stable is when an atom has 8 electrons in the outer shell or energy level

2.  To become stable atoms will gain, lose, or share electrons to reach an octet (8 electrons).

                                                       ii.      Indicated with chemical formulas

1.  formulas show the kind of element

2.  formulas also show the number of atoms in the compound by using subscripts.

3.  How many carbons are in the following compounds?

a.   C₂H₃O₃

b.  Li₂CO₃

                                                   iii.      Three types of Bonds

1.  Ionic Bonds

a.   An attraction between two ions

                                                                                                                                   i.      Cation (positive) Lose

                                                                                                                               ii.      Anion (negative) gain

b.  Due to a transfer of electrons

c.   Between metals and non metals

d.  Use an arrow to show the transfer of electrons

e.   Use Lewis structures to model bonding

f.    Use criss-cross method to determine chemical formula

g.  When dissolved ionic compounds conduct electricity

2.  Covalent Bonds

a.   An attraction between two atoms

b.  Due to sharing of electrons

c.   Between two non-metals

d.  Use circles to show the sharing of electrons

e.   Use Lewis structure to model bonding

f.    Atoms can share more than one pair

                                                                                                                                   i.      Single bond 2 electrons

                                                                                                                               ii.      Double bond 4 electrons

                                                                                                                           iii.      Triple bond  6 electrons

g.  When atoms do not share electrons equally the create polar bonds

                                                                                                                                   i.      Polar bonds- unequal sharing of electrons that creates magnetic type molecules like wax, and water

                                                                                                                               ii.      Non-polar bonds- equal sharing of electrons.

3.  Metallic Bonds

a.   An attraction between two metals

b.  Due to free roaming electrons

c.   Free roaming electrons means that metals

                                                                                                                                   i.      Can conduct electricity

                                                                                                                               ii.      Are malleable and ductile.

 

 

Key Ideas:

9.  How are ionic compounds named? ____________________________________

10.                   What do the numerical prefixed used in naming covalent compounds tell you? ____________________________________________________________

11.                   What does a compound’s empirical formula indicate? ___________________________________________________________

Key Terms:

·      Empirical formula

·      Molecular formula

 

III.       Section 3 ( Compounds Names and Formulas)

a.   Naming Ionic Compounds

                                                           i.      The metal takes its name

1.  ex. Na

2.  sodium

                                                       ii.      The non-metal take its name with an –ide ending

1.  ex. Cl

2.  chlorine becomes chloride

                                                   iii.      Name is Sodium Chloride

                                                    iv.      Practice/

 

b.  Writing formulas from names

                                                           i.      Identifiy the charge of the ions

                                                       ii.      Criss-cross the charges and reduce if needed.

                                                   iii.      Ex.

1.  Mg ⁺² and Cl ^-1

2.  criss cross the charges   Mg Cl₂

c.   Naming Covalent Compounds

                                                           i.      Covalent compounds use prefixes that tell us the number of atoms present.

                                                       ii.      The first element takes a prefix except when it has only one.

1.  ex. CO

2.  one carbon so named carbon

3.  C₂O

4.  two carbons so named dicarbon.

                                                   iii.      The second element always takes a prefix and and –ide ending.

1.  ex. CO

2.  one oxygen so name monoxide.

d.  Writing formulas from names

                                                           i.      Covalent compounds have prefixes that tell you what to write.

                                                       ii.      Record the symbol and use the prefix to get the correct subscript