Question

Name Homework 9 Chemical Bonding CHEM 111-01 April 17, 2018 Due: April 24, 2018 1. On a separate sheet of paper in your own words, define or describe: (2 points each) a. ?bond b. Tr bond c. Molecular orbitals d. Bonding orbital e. Antibonding orbital . Bond order g. Hybridized atomic orbitals h. Delocalized electrons 2. From the following compounds, which are most likely to form ionic bonds? Covalent bonds? (5 points) NaBr, H2O, ??, ??,, KNo,Cl2 onic: Covalent 3. Phenanthrene, C,Hyois a polycyclic aromatic hydrocarbon. It's structure is pictured, at right. (5 points) a. What is the hybridization on the C atoms? b. How many C-H ? bonds are in phenanthrene? C. How many C-C ? bonds are in phenanthrene d. How many bonds are in phenanthrene? On the figure, circle the bonds containing the ? bonds. . Given the molecular orbital scheme, for the CO' ion (5 points) a. How many electrons are involved in the bonding 2p-

Answer 1

1.

a). Sigma bond(? bonds) - Sigma bonds are formed by head on overlapping between atomic orbitals. They are the strongest type of covalent chemical bond.

b). In chemistry, pi bonds (? bonds) are covalent chemical bonds formed by the lateral or sidewise overlap of the half filled atomic orbitals of the atom involved in bonding .

c). A molecular orbital (MO) is a mathematical function describing the wave-like behavior of an electron in a molecule. It can be used to calculate chemical and physical properties such as the probability of finding an electron in any specific region.

d). Bonding molecular orbital is formed by the addition of overlapping of atomic orbitals. The wave function of the bonding MO may be written as-

? (MO) = ?A + ?B.

The electron density is greater in the region between the two nuclei of bonded atoms.

e). Anti-bonding molecular orbital is formed by the subtraction of overlapping of atomic orbitals. The wave function for the anti-bonding MO may be written as:

? (MO) = ?A – ?B.

The electron density is lesser in the region between the two nuclei of the atoms.

f). Bond order is the number of chemical bonds between a pair of atoms.

Bond order = number of bonding electrons – number of antibonding electrons / 2

The bond order for diatomic nitrogen(N2) = 3

g). Hybridisation is the concept of mixing atomic orbitals into new hybrid orbitals (with different energies, shapes, etc., than the component atomic orbitals). Thus hybrid orbitals are type of atomic orbitals that result when two or more atomic orbitals of an isolated atom mix. They are used to describe the orbitals in covalently bonded atoms. Hybrid orbitals have shapes and orientations that are very different from those of atomic orbitals. Hybrid orbitals are very useful in the explanation of molecular geometry and atomic bonding properties.

h). Delocalized electrons are electrons in a molecule, ion or solid metal that are not associated with a single atom or a covalent bond. In organic chemistry, this refers to resonance in conjugated systems and aromatic compounds. In solid-state physics, this refers to free electrons that facilitate electrical conduction. In quantum chemistry, this refers to molecular orbitals that extend over several adjacent atoms.

2.

Ionic bonds are formed by the transfer of electrons from one atom to another and an ionic bond is formed between a metal and a non metal . A covalent bond is formed by the sharing of electrons between atoms and is between a nonmetal and nonmetal atoms

So

Ionic bonds are in NaI, KNO3

Covalent bonds are in H2O, CO,CHCl3 and Cl2