High School Chemistry Rapid Learning Seriesl - 16

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Chemistry :: Biology :: Physics :: Math

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High School Chemistry Rapid Learning Seriesl - 16

Learning Objectives
By completing this tutorial, you will learn…
Valenc...
High School Chemistry Rapid Learning Seriesl - 16

Valence Bond Theory
and the Octet Rule

5/56

Definition: Valence Shell...
High School Chemistry Rapid Learning Seriesl - 16

Definition: Valence Bond Theory
Valence Bond Theory –
Bonds are formed ...
High School Chemistry Rapid Learning Seriesl - 16

Determining # of
Valence Electrons

9/56

Valence Electrons and Periodi...
High School Chemistry Rapid Learning Seriesl - 16

Valence Electrons of Transition Metals
The transition metals don’t have...
High School Chemistry Rapid Learning Seriesl - 16

Definition: Lewis Structure
Lewis Structure – 2D
visualization of how e...
High School Chemistry Rapid Learning Seriesl - 16

Lewis Structures - Covalent
Compounds with 2 Elements

15/56

Drawing B...
High School Chemistry Rapid Learning Seriesl - 16

Binary Covalent Structure #2
Another example:

1

Arrange the atoms sym...
High School Chemistry Rapid Learning Seriesl - 16

Lewis Structures
- Multiple Bonds

19/56

Multiple Bond Example #1 - 1
...
High School Chemistry Rapid Learning Seriesl - 16

Multiple Bond Example #1 - 2
When the previous steps do not result in f...
High School Chemistry Rapid Learning Seriesl - 16

Multiple Bond Example #2 - 2
When the previous steps do not result in f...
High School Chemistry Rapid Learning Seriesl - 16

Lewis Structures - Covalent
Compounds with More
Than 2 Elements

25/56
...
High School Chemistry Rapid Learning Seriesl - 16

Finishing the Lewis Structures
Once you’ve arranged the atoms, finish t...
High School Chemistry Rapid Learning Seriesl - 16

Example #2 - 2
1

Arrange the atoms according to the formula.

2

Deter...
High School Chemistry Rapid Learning Seriesl - 16

Moving Hydrogen Atoms Around
Sometimes, in order to have all atoms with...
High School Chemistry Rapid Learning Seriesl - 16

Definition: Polyatomic Ion
Polyatomic Ion – A group of
atoms covalently...
High School Chemistry Rapid Learning Seriesl - 16

Polyatomic Anion
An anion is a negatively charged ion (gain of electron...
High School Chemistry Rapid Learning Seriesl - 16

Another Approach - 1
1

Arrange the atoms symmetrically or
according to...
High School Chemistry Rapid Learning Seriesl - 16

Another Approach - 3
3

Put one pair of electrons in
between each set o...
High School Chemistry Rapid Learning Seriesl - 16

Another Approach - 5
5

If any atoms do not have full
valences, move a ...
High School Chemistry Rapid Learning Seriesl - 16

A Larger Compound - 2
2

Determine the total # of valence
electrons for...
High School Chemistry Rapid Learning Seriesl - 16

A Larger Compound - 4
4

Place lone pairs around the most
electronegati...
High School Chemistry Rapid Learning Seriesl - 16

Lewis Structures
- Ionic
Compounds

47/56

Definition: Ionic Compound
I...
High School Chemistry Rapid Learning Seriesl - 16

Ionic Compound Example
An ionic compound is between metals and non-meta...
High School Chemistry Rapid Learning Seriesl - 16

Exceptions to
the Octet Rule

51/56

Common Exceptions to the Octet Rul...
High School Chemistry Rapid Learning Seriesl - 16

Exception Examples
B is “full” with 6
electrons.

F B F
F
BF3 = 24 Vale...
High School Chemistry Rapid Learning Seriesl - 16

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You have successfully completed
the core tutorial

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Drawing molecules

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Drawing molecules

  1. 1. High School Chemistry Rapid Learning Seriesl - 16 Rapid Learning Center Chemistry :: Biology :: Physics :: Math Rapid Learning Center Presents… p g Teach Yourself High School Chemistry in 24 Hours 1/56 http://www.RapidLearningCenter.com Drawing Molecules HS Ch i t R id Learning Series Chemistry Rapid L i S i Wayne Huang, PhD Kelly Deters, PhD Russell Dahl, PhD Elizabeth James, PhD Rapid Learning Center www.RapidLearningCenter.com/ © Rapid Learning Inc. All rights reserved. © Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 1
  2. 2. High School Chemistry Rapid Learning Seriesl - 16 Learning Objectives By completing this tutorial, you will learn… Valence Bond Theory The O t t R l Th Octet Rule Lewis Structures for: Elements Covalent Compounds Polyatomic Ions Ionic Compounds p 3/56 Concept Map Previous content Chemistry New content Studies Matter One type is Valence Bond Theory 1 bonding theory is Compounds Shown with Lewis Structures 4/56 © Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 2
  3. 3. High School Chemistry Rapid Learning Seriesl - 16 Valence Bond Theory and the Octet Rule 5/56 Definition: Valence Shell Valence Shell – Outermost shell of electrons; the electrons with the highest principal energy level number; the electrons that form chemical bonds. Cl: 1s2 2s2 2p6 3s2 3p5 7 valence electrons l l t Br: [Ar] 4s 2 3d10 4p5 7 valence electrons 6/56 © Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 3
  4. 4. High School Chemistry Rapid Learning Seriesl - 16 Definition: Valence Bond Theory Valence Bond Theory – Bonds are formed by overlap of valence orbitals from bonding atoms. Valence Bond H H H H s-orbital Both atoms get to “count” the electrons that are being shared between the two. 7/56 Definition: Octet Rule Octet Rule – Most atoms are more stable with a full valence shell (which is a noble gas h ll ( hi h i bl configuration). A full shell has 8 electrons (“oct-” = 8). More exceptions will be discussed soon, but for now, Hydrogen is an exception. Hydrogen’s valence shell only contains a 1s orbital, which can only hold 2 electrons. Therefore, hydrogen is most stable with 2 electrons (one single bond). 8/56 HONC Valence Rule Mnemonic: The electrons needed for full valence shell and covalent bonds formed are H(1), O(2), N(3) and C(4) = HONC © Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 4
  5. 5. High School Chemistry Rapid Learning Seriesl - 16 Determining # of Valence Electrons 9/56 Valence Electrons and Periodic Table The main groups of the periodic table have # of valence electrons = main group #. 1 2 3 4 5 6 7 8 10/56 © Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 5
  6. 6. High School Chemistry Rapid Learning Seriesl - 16 Valence Electrons of Transition Metals The transition metals don’t have easy patterns. Here are some of the common elements: Element Valence Electrons Configuration Cu 2 [Ar] 3d104s1 Zn 2 [Ar] 3d104s2 Cd 2 [Kr]4d105s2 Ag 1 [Kr]4d105s1 Au 3 [Xe]4f145d106s1 Valence electrons in transition metals are not as reliable and predictable as the ones in main group elements. 11/56 Lewis Structures 12/56 © Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 6
  7. 7. High School Chemistry Rapid Learning Seriesl - 16 Definition: Lewis Structure Lewis Structure – 2D visualization of how electrons are shared to form bonds between atoms. Also called: Electron Dot Structures Dot Structures Lewis Dot Structures Lewis Dot Diagrams 13/56 Lewis Structures of Elements How to draw an element’s Lewis structure: 1 Use the element’s symbol to represent the ( ) nucleus and core (non-valence) electrons. 2 Determine the number of valence electrons from the position on the Periodic Table. 3 Draw the electrons around the “nucleus” - one on each side before doubling up (Hund’s Rule - place one in each orbital before doubling). Example: Draw the Lewis Structure for an oxygen atom. Oxygen is in the 6th main group. There are 6 valence electrons. O 14/56 © Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 7
  8. 8. High School Chemistry Rapid Learning Seriesl - 16 Lewis Structures - Covalent Compounds with 2 Elements 15/56 Drawing Binary Covalent Structures For compounds with only 2 different non-metals: 1 Arrange the atoms symmetrically. 2 Determine the # of valence electrons for each atom. 3 Draw the valence electrons - do not double up where 2 atoms are bonding. 4 When atoms have 8 (2 for H) electrons, the structure is done. Example: E l Draw th L i Structure for CH4 D the Lewis St t f H Carbon is in the 4th main group. There are 4 valence electrons. Hydrogen is in the 1st main group. There is 1 valence electron. H C H H 16/56 © Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com Carbon now has 8 electrons it’s sharing. Each hydrogen has 2 electrons it’s sharing. 8
  9. 9. High School Chemistry Rapid Learning Seriesl - 16 Binary Covalent Structure #2 Another example: 1 Arrange the atoms symmetrically. 2 Determine the # of valence electrons for each element. 3 Draw the valence electrons - do not double up where 2 atoms are bonding. 4 When atoms have 8 (2 for H) electrons, the structure is done. Example: E l Draw th L i Structure for NH3 D the Lewis St t f Nitrogen is in the 5th main group. There are 5 valence electrons. Hydrogen is in the 1st main group. There is 1 valence electron. H N H H 17/56 Nitrogen now has 8 electrons it’s sharing. Each hydrogen has 2 electrons it’s sharing. Lone Pairs and Bonding Pairs Lone Pair Electrons not shared in a bond. H N H H Bonding Pair Electrons shared between two atoms. Lone Pairs are “counted” only by the one atom. y y Lone Pairs are important and must be drawn even though they aren’t bonding. Bonding Pairs are “counted” by both atoms that are sharing them. 18/56 © Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 9
  10. 10. High School Chemistry Rapid Learning Seriesl - 16 Lewis Structures - Multiple Bonds 19/56 Multiple Bond Example #1 - 1 Begin with the same steps: 1 Arrange the atoms symmetrically. 2 Determine the # of valence electrons for each element. 3 Draw the valence electrons - do not double up where 2 atoms are bonding. 4 When atoms have 8 (2 for H), the structure is done. the Lewis St t f CO Example: D E l Draw th L i Structure forCO2 Carbon is in the 4th main group. There are 4 valence electrons. Oxygen is in the 6th O C O main group. There are 6 valence electron. Currently, carbon only has 6. And each oxygen only has 7. 20/56 © Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 10
  11. 11. High School Chemistry Rapid Learning Seriesl - 16 Multiple Bond Example #1 - 2 When the previous steps do not result in full valences: 5 Move two unpaired electrons on j adjacent atoms to bond together. Repeat until all atoms have full valence shells. Example: Draw the Lewis Structure for CO2 Now the carbon has 8. O C O And each oxygen also has 8. 21/56 Multiple Bond Example #2 - 1 Begin with the same steps: 1 Arrange the atoms symmetrically. 2 Determine the # of valence electrons for each element. 3 Draw the valence electrons - do not double up where 2 atoms are bonding. 4 When atoms have 8 (2 for H), the structure is done. Example: Draw the Lewis Structure for HCN HCN. Carbon has 4 valence electrons. H C Hydrogen has 1 valence electron. Nitrogen has 5 valence electrons. N But the carbon and nitrogen each only have 6 electrons, not 8. 22/56 © Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 11
  12. 12. High School Chemistry Rapid Learning Seriesl - 16 Multiple Bond Example #2 - 2 When the previous steps do not result in full valences: 5 Move two unpaired electrons j on adjacent atoms to bond together. Repeat until all atoms have full valence shells. Example: Draw the Lewis Structure for HCN HCN. Now all valence shells are full. H C N 23/56 Double and Triple Bonds O C O Double Bond H C N Triple Bond A double bond is 2 pairs of electrons being shared. Double bonds are shorter and stronger than single bonds. 24/56 A triple bond is 3 pairs of electrons being shared. Triple bonds are shorter and stronger than double bonds. © Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 12
  13. 13. High School Chemistry Rapid Learning Seriesl - 16 Lewis Structures - Covalent Compounds with More Than 2 Elements 25/56 What Order do the Elements Go In? When there are more than two elements, how do you arrange them? 1 “COOH” is a carboxylic acid. 2 Hydrogen and halogens (F, Cl, Br, I) can’t go in the middle. 3 Of the elements that can go in the middle, write in the order they’re given. 4 Write the hydrogen and halogen atoms around what they’re next to in the formula. Example: H5C2OH (i.e. CH3CH2OH) Write in this order HH H C C O H HH 26/56 © Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 13
  14. 14. High School Chemistry Rapid Learning Seriesl - 16 Finishing the Lewis Structures Once you’ve arranged the atoms, finish the process: 1 Arrange the atoms according to the formula. 2 Determine the # of valence electrons for each element. 3 Draw the valence electrons - do not double up where 2 atoms are bonding. 4 When atoms have 8 (2 for H), the structure is done. Example: H5C2OH (i.e. CH3CH2OH) Each carbon has 4 electrons. Each hydrogen has 1 electron. The oxygen has 6 electrons. H H H C C O H H H 27/56 Example #2 - 1 1 “COOH” is a carboxylic acid. 2 Hydrogen and halogens (F Cl Br I) can’t go in the (F, Cl, Br, can t middle. 3 Of the elements that can go in the middle, write in the order they’re given. 4 Write the hydrogen and halogen atoms around what they’re next to in the formula. Example: BrH2CCH2COOH Carboxylic acid HHO Br C C C O H HH 28/56 © Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 14
  15. 15. High School Chemistry Rapid Learning Seriesl - 16 Example #2 - 2 1 Arrange the atoms according to the formula. 2 Determine the # of valence electrons for each element. 3 Draw the valence electrons - do not double up where 2 atoms are bonding. 4 When atoms have 8 (2 for H), the structure is done. Example: BrH2CCH2COOH Currently, some of the atoms are full… 29/56 But one carbon and one oxygen each only have 7. H H O Br C C C O H HH Example #2 - 3 5 Move two unpaired electrons on j g adjacent atoms to bond together. Repeat until all atoms have full valence shells. Example: BrH2CCH2COOH All valence shells are currently full. H H O Br C C C O H HH 30/56 © Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 15
  16. 16. High School Chemistry Rapid Learning Seriesl - 16 Moving Hydrogen Atoms Around Sometimes, in order to have all atoms with full valence shells, a hydrogen must be bonded in a different location. Example: C3H6 Each carbon has 4 electrons. Each hydrogen has 1 electron. H H H C C C H H H Two carbons do not have full valence shells. They Th are not adjacent - they cannot double bond. dj h d bl b d If one hydrogen is moved to another carbon… Now two carbons right next to each other have un-full shells and can double bond. 31/56 This move of the hydrogen is not prohibited by the given information (the formula C3H6). Lewis Structures Polyatomic Ions 32/56 © Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 16
  17. 17. High School Chemistry Rapid Learning Seriesl - 16 Definition: Polyatomic Ion Polyatomic Ion – A group of atoms covalently bonded that together have a charge. h h h Examples: NH4+ and SO42-. Common Polyatomic Ions: +1 Cations 2+ Ammonium (NH4+), Hydronium (H3O+), Mercury (I) (Hg22 ). -1 Anions Acetate (C2H3O2), Bicarbonate (HCO3-), Chlorate (ClO3-), Cyanide (CN-), bisulfate (HSO4-), Hydroxide (OH-), Nitrate (NO3-), Nitrite (NO2-), Perchorate (ClO4-), Permanganate (MnO4-). -2 Anions Carbonate (CO32-), Chromate (CrO42-), Dichromate (Cr2O72-), Hydrogen Phosphate (HPO42-), Peroxide (O22-),Sulfate (SO42-), Sulfite (SO32-), Thiosulfate (S2O32-). -3 Anions Phosphate (PO43-) 33/56 Polyatomic Cation A cation is a positively charged ion (loss of electrons). 1 Arrange the atoms according to the formula. 2 Determine th # of valence electrons for each element. D t i the f l l t f h l t 3 Draw the valence electrons - do not double up where 2 atoms are bonding. 4 When atoms have 8 (2 for H), the structure is done. In this case, there is no choice but to double up on a side with a bond. Example: NH4+ Nitrogen has 5 electrons. Each hydrogen has 1 electron. The +1 charge means we can remove 1 electron! H H N H H +1 H’s electron is removed to result in +1 charge. 34/56 © Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 17
  18. 18. High School Chemistry Rapid Learning Seriesl - 16 Polyatomic Anion An anion is a negatively charged ion (gain of electrons). 1 Arrange the atoms according to the formula. 2 Determine th # of valence electrons for each element. D t i the f l l t f h l t 3 Draw the valence electrons - do not double up where 2 atoms are bonding. When atoms have 8 (2 for H), the structure is done. 4 When placing electrons around the oxygen, do not place them where there is already a pair of electrons from sulfur. Example: SO42- O Each oxygen has 6 electrons. O S O The -2 charge means we can add 2 electrons! Warning: This structure satisfies the Octet rule. O However, the more realistic structure is where two -2 Sulfur has 6 electrons. 35/56 2 electrons are added to result in the -2 charge. S=O bonds are formed with resonance structures. Lewis Structures Another Approach 36/56 © Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 18
  19. 19. High School Chemistry Rapid Learning Seriesl - 16 Another Approach - 1 1 Arrange the atoms symmetrically or according to the chemical formula. Example: Draw the Lewis Structure for CO2. O C O 37/56 Another Approach - 2 2 Determine the total # of valence electrons for each element. Example: Draw the Lewis Structure for CO2. Counting electrons: 1 Carbon = 1 × 4 = 4 electrons 2 Oxygens = 2 × 6 = 12 electrons O C O Total = 16 electrons 38/56 © Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 19
  20. 20. High School Chemistry Rapid Learning Seriesl - 16 Another Approach - 3 3 Put one pair of electrons in between each set of atoms. Example: Draw the Lewis Structure for CO2. Counting electrons: 1 Carbon = 1 × 4 = 4 electrons 2 Oxygens = 2 × 6 = 12 electrons Total = 16 electrons O C O Electrons to Fill = 16 12 14 39/56 Another Approach - 4 4 Place lone pairs around the most electronegative atom first (closest to F on the periodic table). Stop when you run out of electrons. t f l t Example: Draw the Lewis Structure for CO2. Counting electrons: Oxygen is more electronegative than carbon. 1 Carbon = 1 × 4 = 4 electrons 2 Oxygens = 2 × 6 = 12 electrons Total = 16 electrons O C O 10 0 2 6 4 8 Electrons to Fill = 12 40/56 © Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 20
  21. 21. High School Chemistry Rapid Learning Seriesl - 16 Another Approach - 5 5 If any atoms do not have full valences, move a lone pair from an adjacent atom in to form a multiple bond. lti l b d Example: Draw the Lewis Structure for CO2. Each oxygen has 8 electrons. But carbon only has 4 electrons. O C O Note: There is a simpler notation where a single bonding pair is replaced with a single line, double bond with a double line and triple bond with a triple line. CO2 becomes … .. .. O .. = C = C .. 41/56 A Larger Compound - 1 1 Arrange the atoms symmetrically or according to the chemical formula. Example: BrH2CCH2COOH H H O Br C C C O H HH 42/56 © Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 21
  22. 22. High School Chemistry Rapid Learning Seriesl - 16 A Larger Compound - 2 2 Determine the total # of valence electrons for each element. Example: BrH2CCH2COOH Counting electrons: 1 Bromine = 1 × 7 = 7 electrons 5 Hydrogens = 5 × 1 = 5 electrons 3 Carbons = 3 × 4 = 12 electrons 2 Oxygens = 2 × 6 = 12 electrons Total = 36 electrons H H O Br C C C O H HH 43/56 A Larger Compound - 3 3 Put one pair of electrons in between each set of atoms. Example: BrH2CCH2COOH Counting electrons: 1 Bromine = 1 × 7 = 7 electrons 5 Hydrogens = 5 × 1 = 5 electrons 3 Carbons = 3 × 4 = 12 electrons 2 Oxygens = 2 × 6 = 12 electrons Total = 36 electrons 44/56 H H O Br C C C O H HH 16 Electrons to Fill = 36 © Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 22
  23. 23. High School Chemistry Rapid Learning Seriesl - 16 A Larger Compound - 4 4 Place lone pairs around the most electronegative atom first (closest to F on the periodic table). Stop when you run out of electrons. t f l t Example: BrH2CCH2COOH Oxygen is most electronegative, followed by bromine. Counting electrons: 1 Bromine = 1 × 7 = 7 electrons 5 Hydrogens = 5 × 1 = 5 electrons 3 Carbons = 3 × 4 = 12 electrons 2 Oxygens = 2 × 6 = 12 electrons Total = 36 electrons H H O Br C C C O H HH 0 6 Electrons to Fill = 16 45/56 A Larger Compound - 5 5 If any atoms do not have full valences, move a lone pair from an adjacent atom in to form a multiple bond. Example: BrH2CCH2COOH All have full valences except one carbon and one oxygen. H H O Br C C C O H HH Now all have full valences! 46/56 © Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 23
  24. 24. High School Chemistry Rapid Learning Seriesl - 16 Lewis Structures - Ionic Compounds 47/56 Definition: Ionic Compound Ionic Compound – Metals transfer electrons to non-metals. The resulting ions form an electrostatic attraction. e.g. KCl, Na2SO4 48/56 © Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 24
  25. 25. High School Chemistry Rapid Learning Seriesl - 16 Ionic Compound Example An ionic compound is between metals and non-metals. 1 Determine the # of valence electrons for each atom. 2 Draw the valence electrons. 3 Transfer electrons from the metals to the nonmetals to fill valence shells. The metal will be left with no electrons in the electrons shell “drawn”. However, the next inner shell is full and it now a full “valence” shell. Example: KCl Potassium has 1 electron. Chlorine has 7 electrons. K +1 Cl -1 49/56 Polyatomic Ionic Compound Example An ionic compound is between metals and non-metals. 1 Determine the # of valence electrons for each atom. 2 Draw the valence electrons. 3 Transfer electrons from the metals to the nonmetals to fill valence shells. The total charge should = 0 Example: Na2SO4 Each sodium has 1 electron. SO42- is a polyatomic ion - it must be covalently bonded first. Na Na +1 +1 -2 O -1 O S O O 50/56 © Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 25
  26. 26. High School Chemistry Rapid Learning Seriesl - 16 Exceptions to the Octet Rule 51/56 Common Exceptions to the Octet Rule # of Valence Electrons when “Full” Element(s) 2 H, H He (i e H2, He) (i.e. 4 Be (i.e. BeCl2) 6 B >8 Any l A element i the 3rd period t in th i d and below. (i.e. PF5, SF6) (i.e. BCl3) Elements in period 3 and below have empty “d” orbitals that can be used to hold more than 8 valence electrons (18 Electrons Rule). Free radicals with one unpaired electron clearly do not follow the Octet rule. 52/56 Octet Exception Mnemonic: H&He: 2; Be: 4; B = 6; S&P > 8 = “2 Hawks and Hens (2-legs); 4 Bears (4-legs); 6 Bugs (6-legs); many SPiders (<8 legs).” © Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 26
  27. 27. High School Chemistry Rapid Learning Seriesl - 16 Exception Examples B is “full” with 6 electrons. F B F F BF3 = 24 Valence Electrons (Trigonal Planar Geometry) S F S has 10 electrons. SF5+ = 40 Valence Electrons (Trigonal Bipyramidal Geometry) 53/56 Learning Summary Elements bond to obtain a full valence shell - for most elements, that means 8 (the Octet Rule). Lewis Structures are used to show the valence electrons and their arrangement in compounds. Covalent compounds share electrons, while ionic compounds transfer electrons from one atom to another. 54/56 © Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 27
  28. 28. High School Chemistry Rapid Learning Seriesl - 16 Congratulations You have successfully completed the core tutorial Drawing Molecules Rapid Learning Center Rapid Learning Center Chemistry :: Biology :: Physics :: Math What’s N t Wh t’ Next … Step 1: Concepts – Core Tutorial (Just Completed) Step 2: Practice – Interactive Problem Drill Step 3: Recap – Super Review Cheat Sheet Go for it! 56/56 http://www.RapidLearningCenter.com © Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 28

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