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IONIC BONDING 

 

Stability 

The Octet Rule 

The  noble  gases  are  the  chemical  elements  in group 18 of 
the  periodic  table
...
  Therefore,  they  rarely  react  with  other 
elements since they are already stable
...
  They  may  accomplish  this  by  either  giving 
electrons away or taking them
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● are formed between a metal and a nonmetal 
*atoms that have gained or lost electrons are called ions 
○ metals 
give 
electrons 
and 
become 
positively-charged cations 
○ nonmetals  take  electrons  and  become 
negatively-charged anions 
● tend to be stronger than ionic compounds 

● are formed between two nonmetals 
○ transfer of electrons between nonmetals  

● have high melting and boiling point 
○ Why?  ​Because  ionic  bonds  are  relatively  strong; 
thus,  ionic  crystals  require  a  large  amount  of 
energy to be broken apart 

● generally have much lower melting and boiling points 

● are poor conductor of electric current as solids 
○ Why?  ​In  the  solid  state,  the  ions  in  an  ionic 
compound  are  locked into fixed positions by strong 
attractive forces
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The  symbol  for  the  cation  is  always  written  first, 
followed by the symbol of the anion
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Subscripts  represent  the  number  of  ions  of  each 
element in an ionic compound
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3
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Polyatomic Ions  
● are ions made up of more than one atom 
● acts  as  an  individual  ion  in  a  compound  and  its  charge 
applies to the entire group of atoms  
● The  formula  for  a  polyatomic  ion follows the same rules 
of used for a binary compound 
○ Because  a  polyatomic  ion  exists  as  a unit, ​never 
change subscripts of polyatomic ions
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4
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To  distinguish  between different oxidation states 
of  the  same  element,  the  oxidation  state  is 
written  in  parentheses  after  the  name  of  the 
cation
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REVIEW: 
Why do atoms bond?  
● Atoms  gain stability when they share electrons and form 
covalent bonds
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● Gaining  or  losing  electrons  makes atoms more stable by 
forming ions with noble-gas electron configurations
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Covalent Bonds 
Shared Elections 
● Atoms in non-ionic compounds share electrons
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● A ​molecule i​ s formed when two or more atoms bond
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● Covalent  bonding  generally can occur between elements 
that are near each other on the periodic table
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○ Hydrogen (H​2​) 
○ Nitrogen (N​2​) 
○ Fluorine (F​2​) 
○ Chlorine (Cl​2​) 
○ Bromine (Br​2​) 
○ Iodine (I​2​) 

Names for Ions and Ionic Compounds 

Naming an oxyanion 
● An ​oxyanion ​is a polyatomic ion composed of an 
element (usually a non-metal), bonded to one or more 
oxygen atoms 
Naming Ionic compounds 
● Chemical nomenclature​ is a systematic way of naming 
compounds
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Name the cation followed by the anion
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For monatomic, cations use the element name
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For  monatomic  anions,  use  the  root  element 
name and the suffix –ide
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Repulsion  occurs  between  nuclei  and  between  electron 
clouds 
● The  distance  is  right  for  the  attraction  between  one 
atom’s  protons  and  the  other  atom’s  electrons  to  make 
the bond stable 
● If  the  atoms  are  forced  closer  together,  the  nuclei  and 
electrons repel each other 

 
The most stable arrangement of atoms in a covalent bond exists at 
some optimal distance between nuclei
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Molecular Compounds 
● the chemical formula of a molecular compound
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● A  ​molecular  formula  ​shows  the  actual  number  of 
atoms,  while  a  formula  unit  (for  ionic  compounds) 
shows the lowest whole-number ratio of ions
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○ The  shared  electron  pair  of  a  pi  bond occupies the 
space  above  and  below  the  line  that  represents 
where the atoms are joined together 

Single Covalent Bonds 
●

When  only  one  pair  of  electrons  is  shared,  such  as  in  a 
hydrogen molecule, it is a single covalent bond
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Naming Binary Molecular Compounds 

 
 

 
Multiple Covalent Compounds 
●

Sharing  multiple  pairs  of  electrons  forms  multiple 
covalent bonds 
Double Bonds 
○ form  when  two  pairs  of  electrons  are  shared 
between two atoms 

 
●

Triple Bonds 
○ form  when  three  pairs  of  electrons  are  shared 
between two atoms 

The  strength  depends  on  the  distance  between  the  two 
nuclei, or bond length
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The  amount  of  energy  required to break a bond is called 
the bond dissociation energy
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1
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2
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3
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Exceptions: 
● The  first  element  in  the  compound  name ​never ​uses 
the ​mono-- p
​ refix 
● If  using  a  prefix  results  in  two  consecutive  vowels, 
one  of  the  vowels  is  usually  dropped  to  avoid  an 
awkward pronunciation 

Naming Acids 
1
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2
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Oxyacid 
●
●

an  acid  that  contains  both  a  hydrogen  atom  and  an 
oxyanion 
Naming Oxyacids 
○ Identify the oxyanion present
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An  acid,  whether  a  binary  acid  or  an  oxyacid,  can  have  a 
common name in addition to its compound name
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Write the correct skeletal structure for the molecule 
2
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  of  electrons  for  the  Lewis 
structures  by  summing up the valence electrons of each 
atom in the molecule
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Distribute  the  electrons  among  the atoms, giving octets 
to as many atom s as possible
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4
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Too few electrons- Electron deficient molecule 
● Molecules  where  some  atoms  have  fewer  than 
eight electrons are called electron deficient
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2
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Lonely Electrons - Free Radicals 
● Free  radicals  contain  at  least  one  unpaired 
electron in their valence shell 
● Molecules  with  an  odd  number of electrons tend to be 
free radicals 



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