Alchemy In V Lesson 2 Electron Glue · • Two or more atoms can be connected together into units called molecules. ... Alchemy In V Lesson 2 Electron Glue.pptx Author: Byron Asakawa

Alchemy  Unit  –  Inves1ga1on  V  

Lesson 2:  Electron Glue  

Unit 1 • Investigation V

ChemCatalyst    

•  A  gold  ring  is  made  up  of  individual  gold  atoms.    •  What do you think holds these

atoms together? •  What do we call the glue that

keeps the atoms together? •  What parts of the atom do you

think are responsible for keeping the atoms together?  

Unit 1 • Investigation V

ChemCatalyst    

•  A  balloon  is  filled  with  atoms  of  helium.    •  What happens to those

atoms when the balloon is opened?

•  Why don’t these atoms stay together?  

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The  Big  Ques1on  

•  How  can  we  use  bonding  to  explain  the  proper1es  of  substances  we  encounter?  

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You  will  be  able  to:  

•  Classify  the  kind  of  bonding  that  occurs  in  the  making  of  brass,  sand,    water,  or  salt.  

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Notes  for  “Chemical  Bonds”  While  viewing  the  video,  “Chemical  Bonds”.  

•  Try  to  find  out  what  binds  one  atom  to  another  atom.    •  Describe  the  various  bonds,  especially  covalent  and  ionic  bonds.  

•  List  the  proper1es  of  compounds  formed  by  these  bonds.  

•  What  are  electrolytes  and  non-­‐electrolytes?  •  Give  examples  of  compounds  with  covalent  bonds.  •  Give  examples  of  compounds  held  together  by  and  ionic  bonds.  

•  Explain  what  happens  to  energy  when  more  stable  bonds  are  made.  

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•  A  chemical  bond  is  an  aSrac1on  between  atoms  that  holds  them  together  in  space.  

•  The  bonds  or  glue  that  holds  atoms  together  are  formed  by  the  valence  or  outer  electrons  in  an  atom  and  the  outer  shell  where  electrons  are  found.    

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Notes

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•  If two atoms approach each other with enough energy to overcome their charge repulsion… •  and stay together to form a “covalent bond” or… • the atom and core electrons separate, but the valence electrons stay with just one of the atoms

Notes  

•  What are valence orbitals? •  What are valence electrons? •  How can you tell which electrons are valence

electrons in an electron configuration? •  What subshells make up the valence shell for

silicon? •  How many valence electrons does silicon

have?

Unit 1 • Investigation V

Notes  

•  What is an electrolyte (Check your video notes)? What do they form when added to water?

•  What is an ion? •  How can a neutral atom be changed into a

positive ion of the same element? What are these ions called?

•  How can a neutral atom be changed into a negative ion of the same element? What are these ions called?

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Ac1vity  

•  Purpose: This lesson helps to explain the physical properties of basic substances by examining the types of bonds that exist between the atoms of these substances.    

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(cont.)

Four  common  types  of  bonds  

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Ionic Covalent Network Metallic

Molecular Covalent

(cont.)

Notes:  Copy  this  table  (full  page)  Kind of

Bond Description Drawing Properties Examples

Ionic

Covalent Network Metallic

Molecular Covalent Polar Covalent

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Model  1:  IONIC  •  The  blue  areas  represent  outer  

electrons  around  the  metal  (yellow)  atoms  and  non-­‐metals  (red)  atoms.    

•  Metal  atoms  “gave  up”  their  valence  electrons  to  non-­‐metal  atoms,  leaving  them  with  a  posi1ve  charge.    

•  The  non-­‐metal  atoms  took  the  valence  electrons  of  the  metals,  giving  them  more  electrons  than  protons  and  a  net  nega1ve  charge.  

•  These  charged  par1cles  are  called  IONS.  

•  Because  of  their  opposite  charges,  these  ions  are  aSracted  to  each  other.  

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Model  1:  IONIC  

•  Proper1es:    •  Made  of  metal  and  non-­‐metal  atoms  •  When  these  compounds  dissolve  in  water,  they  tend  to  separate  into  electrically  charged  par1cles  called  IONS.  

•  Conducts  electricity  when  dissolved  in  water  but  not  when  solid  (unless  melted  into  a  liquid  by  hea1ng)  

•  BriSle  solids  •  Example  :  Salt  (sodium  chloride),  Copper  (II)  sulfate,  Calcium  chloride  

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Ionic  Bonds:  One  big  greedy  thief  dog!  

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Ionic bonding can be best imagined as one big greedy dog stealing the other dog's bone. If the bone represents the electron that is up for grabs, then when the big dog gains an electron he becomes negatively charged and the little dog who lost the electron becomes positively charged. "The two ions (that's where the name ionic comes from) are attracted very strongly to each other as a result of their opposite charges."

Model  2:  COVALENT  NETWORK  

•  Descrip1on  of  drawing:  Valence  electrons  (blue)  connect  atoms  with  each  other  in  all  direc1ons  –  like  a  grid  or  network.  

•  The  mul1ple  connec1ons  make  the    resul1ng  substance  rigid  and  strong.  

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Model  2:  COVALENT  NETWORK  

•  Proper1es:  •  Made  en1rely  of  nonmetal  atoms  •  Does  not  dissolve  in  water  •  Does  not  conduct  electricity  •  Very  hard  solids  

•  Example  -­‐  Diamond,  sand.  

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Covalent  Network  Bonds:    Dogs  share  bones  to  make  a  grid.  

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 These bonds are found in substances made of non-metal atoms that share electrons with each other to form a grid or network of bonding atoms." It involves many atoms (dogs) which shares many bones with other dogs. This makes the bonds strong and results in solids being formed which are hard and rigid. " The silicon chips, diamonds and graphite are examples of substances held together by network covalent bonds."

Model  3:  METALLIC  

•  Descrip1on  of  drawing:  Valence  electrons  (blue)  are  free  to  move  throughout  the  substance  like  a  “sea”  of  electrons.  

•  Since  the  atoms  are  in  the  suspended  in  the  electron  sea,  the  atoms  can  be  pushed  around  and  the  valence  electrons  are  free  to  move  around.  

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Model  3:  METALLIC  

•  Proper1es:  •  Made  en1rely  of  metal  atoms  •  Do  not  dissolve  in  water  •  Conduct  electricity  •  Bendable  solids  

•  Example:  brass,  gold,  copper,  aluminum,  zinc  

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Metallic  Bonds:    Mellow  dogs  with  plenty  of  bones  to  go  around.  

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These bonds are best imagined as a room full of puppies who have plenty of bones to go around and are not possessive of any one particular bone. This allows the electrons to move through the substance with little restriction. ""The model is often described as the "kernels of atoms in a sea of electrons."

Model  4:  MOLECULAR  COVALENT  

•  Descrip1on  of  drawing:  Valence  electrons  (blue)  are  shared  between  some  atoms.  This  creates  numerous  small  stable  units  within  the  substance.  

•  Since  the  stable  units  are  small,  they  separate  from  each  other  easier.  

Unit 1 • Investigation V

Model  4a:  MOLECULAR  COVALENT  •  Proper1es:  

•  Made  of  nonmetal  atoms  •  Some  dissolve  in  water,  some  do  not  •  Do  not  conduct  electricity  •  Tend  to  be  liquids  or  gases  or  so^er  solids  

•  Example:  Water,  Methane  (natural  gas),  oxygen  (in  air),  wax  (paraffin),  sugar  

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Molecular  Covalent  Bonds:    Mellow  dogs  that  share  bones!  

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Covalent bonds can be thought of as two or more dogs with attraction to the bones. Suppose the dogs (atoms) are similar. Then they will share the pairs of available bones equally. ""Since one dog does not have more of the bone than the other dog, the charge is evenly distributed among both dogs.

Model  4b:  POLAR  COVALENT  

•  Descrip1on  of  drawing:  Valence  electrons  are  shared  unequally  between  some  atoms.  This  creates  small  stable  units  within  the  substance  with  a  par1al  posi1ve  charge  on  one  end  and  a  par1al  nega1ve  charge  on  the  other  end.  

•  Example:  Water.  

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Model  4b:  POLAR  COVALENT  •  Proper1es:  

• Made  of  nonmetal  atoms  • Most  dissolve  in  water  •  O^en  will  dissolve  ionic  compounds  •  Do  not  conduct  electricity  •  Tend  to  be  liquids  or  gases  or  so^er  solids  

•  Example:  Water,  Ammonia,  sugar  

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Polar  Covalent  Bonds:  Unevenly  matched  but  willing  to  share.  

•  These  bonds  can  be  thought  of  as  two  or  more  dogs  that  have  different  desire  for  bones.    The  bigger  dog  has  more  strength  to  possess  a  larger  por1on  of  the  bones.    Sharing  s1ll  takes  place  but  is  an  uneven  sharing.    In  the  case  of  the  atoms,  the  electrons  spend  more  1me  on  the  end  of  the  molecule  near  the  atom  with  the  greater  electronega1vity  (desire  for  the  electron)  making  it  seem  more  nega1ve  and  the  other  end  of  the  molecule  seem  more  posi1ve.charge  than  the  other.  

Unit 1 • Investigation V

•  Two or more atoms can be connected together into units called molecules. These units may be composed of only two atoms or of dozens of atoms.

•  Since the valence electrons in ionic compounds are bound to only the anion, they are attracted to cations but not connected to them. The ratio of cations to anions referred to as a formula unit.

•  What kind of clues can tell us what kind of bond two atoms might form?

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Notes (cont.)

Bonding  based  on  proper1es  

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NaCl – salt CaCl2 – calcium chloride CuSO4 – copper sulfate

H2O – water C12H22O11 – sugar C2H6O – ethanol

Au – gold Cu – copper Al – aluminum

SiO2 – sand

Dissolves

Yes No

Solution Conducts

Yes Yes No No

Compound Conducts

Ionic Molecular Covalent

Metallic Covalent Network

C20H42 – paraffin

C20H42 – paraffin

Clues  based  on  composi1on  

Metal + Metal atoms

Non-Metal + Non-Metal

atoms

Metal & Non-Metal

atoms

Metallic Covalent Network

Molecular Covalent Ionic

Notes (cont.)

Hard solids

Covalent

Soft solids, liquids. gases

Polar Covalent

Dissolves in water

Check-­‐In  

•  When tested with a conductivity tester, brass lights up the LEDs (indicator lights). On the very first day of class, you combined copper with zinc to form brass. How would you classify the bonding in brass? Explain.  

•  When sodium is added to chlorine, it reacts to form a white solid. The solid dissolves in water and the water now conducts electricity. How would you classify the bonding between sodium and chlorine?

Unit 1 • Investigation V

Wrap-­‐Up  

• A chemical bond is an attraction between atoms involving the electrons in the outer shell - valence electrons.

•  There are four basic types of bonds -ionic, extended or network covalent, molecular covalent, and metallic.

Unit 1 • Investigation V