COVALENT BONDING NOTES
DEFINITIONS:
- In covalent bonds, the sharing of electrons usually occurs so that atoms can get the electron configurations of the noble gas.
- A coordinate covalent bond is different from other covalent bonds as one atom in the bond contributes 2 electrons for the bond and the other atom does not contribute any.
- One way in which the octet rule can sometimes fail to be obeyed is within molecules in which an atom has less than a total octet of valence electrons.
STRUCTURAL:
- Another way is within molecules in which an atom has more than a complete octet of valence electrons. The third way is in molecules whose total number of valence electrons is an odd number.
- The strength of a covalent bond is related to the bond dissociation energy as a large bond dissociation energy corresponds to a strong covalent bond.
- Resonance structures are used to represent a covalent bond because it is another way of representing the structure of the atoms within a molecule.
- An electron dot structure is used to represent a covalent bond as it shows the particular and a number of electrons that are shared in the bond.
- A triple bond forms double or triple covalent bonds if they can achieve a noble gas structure by sharing two pairs or three pairs of electrons.
- A structural formula reveals that the compound it represents has covalent bonds as dashes and shows the order of covalently bonded atoms.
- A hydrogen bond is stronger because a hydrogen double bond has a more powerful bond dissociation energy.
- Scientists are conservative.
CLIMATE CHANGE:
- The temperature of Earth increased by 1C, for which more than half of the ice in The Arctic melted. Huge amounts of freshwater in the northern hemisphere/ocean = slow down the current of the gulf stream, which distributes heat.
- In arid areas, there is more evaporation = drought.
- When people claim they cannot breathe, it is often due to the increase in temperature in the atmosphere, due to climate change.
- Advantages of powder coating are resistant to fading, chipping, scratching, and wearing than other forms of finishes. The atom and the molecules bond together so they could stay close to each other.
ELECTRONEGATIVITY NOTES:
- Electronegativity values determine the charge distribution in a polar covalent bond as the more electronegative atom attracts electrons more strongly and gains a slightly negative charge in polar covalent bonds.
- The less electronegative atom has a slightly positive charge in polar covalent bonds.
INTERMOLECULAR ATTRACTIONS:
- The strengths of intermolecular attractions compare to the strengths of ionic bonds and covalent bonds as Intermolecular attractions are weaker than ionic and covalent bonds.
- The properties of covalent compounds are so diverse because of widely varying intermolecular attractions.
- When examining the structure of a carbon tetrachloride molecule, the molecule is noticed to be symmetrical so the polar bonds cancel, making it a nonpolar molecule.
NETWORK SOLIDS:
- A network solid is different from most other covalent compounds because it consists of molecules that form a solid-like structure.
- For example, NaCl would form a solid with cubes, while covalent networking does the same.
POLAR MOLECULES:
- When polar molecules are placed between oppositely charged metal plates, they tend to become oriented with regard to the positive and negative plates.
- Atomic orbitals and molecular orbitals are related as atomic orbitals are properties of individual atoms, while molecular orbitals are properties of the entire molecule.
- When two atoms merge, atomic orbitals combine to produce molecular orbitals.
VSEPR THEORY:
- Scientists use the VSEPR theory because electrons have a negative charge and repel each other, each molecule assumes the shape that places valence-electrons pairs as far apart as possible.
- Orbital hybridization provides information useful in describing molecules as the types of covalent bonds, molecular bonding, and molecular shape are provided.
- What shape would you expect a simple carbon-containing compound to have if the carbon atom has the following hydration?
a. sp - Trigonal Planar shape 2
b. Sp - Tetrahedral shape 3
c. Sp - Linear Shape
SIGMA BOND:
- What is a sigma bond? Describe, with the aid of a diagram, how the overlap of two half-filled 1s orbitals produces a sigma bond.
- A sigma bond is a bond formed when two atomic orbitals merge to create a molecular orbital that is symmetrical around the axis attaching two atomic nuclei.
- Explain why compounds containing C - N and C - O single bonds can form coordinate covalent bonds with H+ but compounds containing only C - H and C - C single bonds cannot.
- Unshared electron pairs are needed to coordinate covalent bonds. In compounds with only C-H and C-C bonds, there are no unshared pairs of electrons. Page 257
- How must the electronegativities of two atoms compare if a covalent bond between them is to be polar?
- The electronegativities of two atoms must be different if the polar covalent bond is present because one atom must pull shared electrons more strongly.
COVALENT BONDING NOTES
DEFINITIONS:
- In covalent bonds, the sharing of electrons usually occurs so that atoms can get the electron configurations of the noble gas.
- A coordinate covalent bond is different from other covalent bonds as one atom in the bond contributes 2 electrons for the bond and the other atom does not contribute any.
- One way in which the octet rule can sometimes fail to be obeyed is within molecules in which an atom has less than a total octet of valence electrons.
STRUCTURAL:
- Another way is within molecules in which an atom has more than a complete octet of valence electrons. The third way is in molecules whose total number of valence electrons is an odd number.
- The strength of a covalent bond is related to the bond dissociation energy as a large bond dissociation energy corresponds to a strong covalent bond.
- Resonance structures are used to represent a covalent bond because it is another way of representing the structure of the atoms within a molecule.
- An electron dot structure is used to represent a covalent bond as it shows the particular and a number of electrons that are shared in the bond.
- A triple bond forms double or triple covalent bonds if they can achieve a noble gas structure by sharing two pairs or three pairs of electrons.
- A structural formula reveals that the compound it represents has covalent bonds as dashes and shows the order of covalently bonded atoms.
- A hydrogen bond is stronger because a hydrogen double bond has a more powerful bond dissociation energy.
- Scientists are conservative.
CLIMATE CHANGE:
- The temperature of Earth increased by 1C, for which more than half of the ice in The Arctic melted. Huge amounts of freshwater in the northern hemisphere/ocean = slow down the current of the gulf stream, which distributes heat.
- In arid areas, there is more evaporation = drought.
- When people claim they cannot breathe, it is often due to the increase in temperature in the atmosphere, due to climate change.
- Advantages of powder coating are resistant to fading, chipping, scratching, and wearing than other forms of finishes. The atom and the molecules bond together so they could stay close to each other.
ELECTRONEGATIVITY NOTES:
- Electronegativity values determine the charge distribution in a polar covalent bond as the more electronegative atom attracts electrons more strongly and gains a slightly negative charge in polar covalent bonds.
- The less electronegative atom has a slightly positive charge in polar covalent bonds.
INTERMOLECULAR ATTRACTIONS:
- The strengths of intermolecular attractions compare to the strengths of ionic bonds and covalent bonds as Intermolecular attractions are weaker than ionic and covalent bonds.
- The properties of covalent compounds are so diverse because of widely varying intermolecular attractions.
- When examining the structure of a carbon tetrachloride molecule, the molecule is noticed to be symmetrical so the polar bonds cancel, making it a nonpolar molecule.
NETWORK SOLIDS:
- A network solid is different from most other covalent compounds because it consists of molecules that form a solid-like structure.
- For example, NaCl would form a solid with cubes, while covalent networking does the same.
POLAR MOLECULES:
- When polar molecules are placed between oppositely charged metal plates, they tend to become oriented with regard to the positive and negative plates.
- Atomic orbitals and molecular orbitals are related as atomic orbitals are properties of individual atoms, while molecular orbitals are properties of the entire molecule.
- When two atoms merge, atomic orbitals combine to produce molecular orbitals.
VSEPR THEORY:
- Scientists use the VSEPR theory because electrons have a negative charge and repel each other, each molecule assumes the shape that places valence-electrons pairs as far apart as possible.
- Orbital hybridization provides information useful in describing molecules as the types of covalent bonds, molecular bonding, and molecular shape are provided.
- What shape would you expect a simple carbon-containing compound to have if the carbon atom has the following hydration?
a. sp - Trigonal Planar shape 2
b. Sp - Tetrahedral shape 3
c. Sp - Linear Shape
SIGMA BOND:
- What is a sigma bond? Describe, with the aid of a diagram, how the overlap of two half-filled 1s orbitals produces a sigma bond.
- A sigma bond is a bond formed when two atomic orbitals merge to create a molecular orbital that is symmetrical around the axis attaching two atomic nuclei.
- Explain why compounds containing C - N and C - O single bonds can form coordinate covalent bonds with H+ but compounds containing only C - H and C - C single bonds cannot.
- Unshared electron pairs are needed to coordinate covalent bonds. In compounds with only C-H and C-C bonds, there are no unshared pairs of electrons. Page 257
- How must the electronegativities of two atoms compare if a covalent bond between them is to be polar?
- The electronegativities of two atoms must be different if the polar covalent bond is present because one atom must pull shared electrons more strongly.
