⢠Coordinate covalent bonds
• Coordinate covalent bonds – one atom contributes both bonding electrons – once formed they act like other covalent bonds – example: CO
Slide 1 of 22
• Resonance structures – occur when there is more than one valid way to draw an electron dot structure – the molecule does not flip back and forth, – the electrons are spinning in their cloud shapes, being shared in different ways around the central atom
Slide 2 of 22
• Polyatomic ions – groups of atoms joined by covalent bonds – carry a charge and act like an ion in a bond – example: ammonium ion NH4+
Slide 3 of 22
1. Phosphate •
PO43‐
2. Nitrate •
NO3‐
3. Carbonate •
CO32‐
4. Sulfate •
SO42‐
5. Ammonium •
NH4+
Slide 4 of 22
Slide 5 of 22
8.3
Bonding Theories
This car is being painted by a process called electrostatic spray painting. The negatively charged droplets are attracted to the auto body. You will learn how attractive and repulsive forces influence the shapes of molecules. Slide 6 of 22 © Copyright Pearson Prentice Hall
11. Describe how VSEPR theory helps predicts the shapes of molecules, and use a VSEPR theory flowchart to determine the three dimensional shapes of molecules.
Slide 7 of 22
• Valence Shell Electron‐Pair Repulsion theory – Electron pairs repel each other – Molecules adjust their shape so that the valence‐electron pairs are as far apart as possible
Slide 8 of 22
• Lewis structures fail to represent the three dimensional shapes of objects – ammonia (NH3) • has one unshaired pair of electrons • draw the Lewis structure
Slide 9 of 22
The measured H—N—H bond angle is only 107°.
Slide 10 of 22
• Common molecular shapes 1. 2. 3. 4. 5. 6.
linear trigonal planar (planar triangular) tetrahedral bent triatomic pyramidal (trigonal, square) trigonal bipyramidal
Slide 11 of 22
8.3
Bonding Theories > VSEPR Theory
Nine Possible Molecular Shapes
Slide 12 of 22 © Copyright Pearson Prentice Hall
8.3
Bonding Theories > VSEPR Theory
The hydrogens in a methane molecule are at the four corners of a geometric solid. All of the H—C—H angles are 109.5°, the tetrahedral angle.
Slide 13 of 22 © Copyright Pearson Prentice Hall
• Determining molecular shape using VSEPR theory 1. Draw a valid Lewis structure 2. Then follow the flowchart • Determine the total # of “things” (atoms and unshared pairs of e‐s) bonded to the central atom • Then use the number of unshared pairs of e‐ to determine the final shape Slide 14 of 22
• Example: – What is the shape of a water molecule? 1. Draw a Lewis structure 2. Follow the flowchart
Slide 15 of 22
• Nonlinear/Bent Triatomic
Slide 16 of 22
• Carbon dioxide (CO2) 1. Draw a Lewis structure 2. Follow the flowchart, • Count the “things” around the central atom (other atoms bonded to it and unshaired pairs of e‐) • Remember a double bond counts as one “thing”
Slide 17 of 22
– Linear triatomic
Slide 18 of 22
• Sulfur dichloride (SCl2)
– bent triatomic Slide 19 of 22
• Silicon tetrachloride (SiCl4)
– Tetrahedral Slide 20 of 22
8.3 Section Quiz.
VSEPR theory enables prediction of 3‐dimensional molecular shape because the valence electron pairs A. are attracted to each other. B. form molecules with only four possible shapes. C. stay as far apart as possible. D. always form tetrahedral shapes. © Copyright Pearson Prentice Hall
Slide 21 of 22
• Q 54, pg 247 • Read 237‐240
Slide 22 of 22
Slide 1 of 22
• Resonance structures – occur when there is more than one valid way to draw an electron dot structure – the molecule does not flip back and forth, – the electrons are spinning in their cloud shapes, being shared in different ways around the central atom
Slide 2 of 22
• Polyatomic ions – groups of atoms joined by covalent bonds – carry a charge and act like an ion in a bond – example: ammonium ion NH4+
Slide 3 of 22
1. Phosphate •
PO43‐
2. Nitrate •
NO3‐
3. Carbonate •
CO32‐
4. Sulfate •
SO42‐
5. Ammonium •
NH4+
Slide 4 of 22
Slide 5 of 22
8.3
Bonding Theories
This car is being painted by a process called electrostatic spray painting. The negatively charged droplets are attracted to the auto body. You will learn how attractive and repulsive forces influence the shapes of molecules. Slide 6 of 22 © Copyright Pearson Prentice Hall
11. Describe how VSEPR theory helps predicts the shapes of molecules, and use a VSEPR theory flowchart to determine the three dimensional shapes of molecules.
Slide 7 of 22
• Valence Shell Electron‐Pair Repulsion theory – Electron pairs repel each other – Molecules adjust their shape so that the valence‐electron pairs are as far apart as possible
Slide 8 of 22
• Lewis structures fail to represent the three dimensional shapes of objects – ammonia (NH3) • has one unshaired pair of electrons • draw the Lewis structure
Slide 9 of 22
The measured H—N—H bond angle is only 107°.
Slide 10 of 22
• Common molecular shapes 1. 2. 3. 4. 5. 6.
linear trigonal planar (planar triangular) tetrahedral bent triatomic pyramidal (trigonal, square) trigonal bipyramidal
Slide 11 of 22
8.3
Bonding Theories > VSEPR Theory
Nine Possible Molecular Shapes
Slide 12 of 22 © Copyright Pearson Prentice Hall
8.3
Bonding Theories > VSEPR Theory
The hydrogens in a methane molecule are at the four corners of a geometric solid. All of the H—C—H angles are 109.5°, the tetrahedral angle.
Slide 13 of 22 © Copyright Pearson Prentice Hall
• Determining molecular shape using VSEPR theory 1. Draw a valid Lewis structure 2. Then follow the flowchart • Determine the total # of “things” (atoms and unshared pairs of e‐s) bonded to the central atom • Then use the number of unshared pairs of e‐ to determine the final shape Slide 14 of 22
• Example: – What is the shape of a water molecule? 1. Draw a Lewis structure 2. Follow the flowchart
Slide 15 of 22
• Nonlinear/Bent Triatomic
Slide 16 of 22
• Carbon dioxide (CO2) 1. Draw a Lewis structure 2. Follow the flowchart, • Count the “things” around the central atom (other atoms bonded to it and unshaired pairs of e‐) • Remember a double bond counts as one “thing”
Slide 17 of 22
– Linear triatomic
Slide 18 of 22
• Sulfur dichloride (SCl2)
– bent triatomic Slide 19 of 22
• Silicon tetrachloride (SiCl4)
– Tetrahedral Slide 20 of 22
8.3 Section Quiz.
VSEPR theory enables prediction of 3‐dimensional molecular shape because the valence electron pairs A. are attracted to each other. B. form molecules with only four possible shapes. C. stay as far apart as possible. D. always form tetrahedral shapes. © Copyright Pearson Prentice Hall
Slide 21 of 22
• Q 54, pg 247 • Read 237‐240
Slide 22 of 22
