Lecture 1 Flashcards
What determines the nature of chemical bond between atoms
Distribution pattern of electrons in atoms orbital
No of electrons
Enegativity
Bohr atomic model:
.
• Electrons revolve around the nucleus in discrete orbitals
Nucleus
Nucleus ~ 10-14 m diameter surrounded by electron cloud. Atomic diameter ~ 10-10 m
~ 99.98% of mass is in nucleus & most of volume is electron cloud.
Wave like mechanical model
Elec have both wave and particle like properties
Elec In orbitals determined by probability distribution
Energy is quantized
What is the probability distribution
Unlike bones fixed orbitals electrons are classified by a probability distribution or e clouds.
These clouds represent the region where the electron is likely to be
What does it mean when we say energy for electrons is quantized in wave like mech model
Electrons can exist only in specific energy levels but can jump to higher when absorb energy and to lower when lose energy and this is called quantum jumping
Valence electrons
Involved I. The atoms chemical interactions and determine its behaviors
E negativity range
.7 to 4
Quantu, numbers
N principle energy describes energy level
L subsidiary orbitals shape of orbitals ( s p d f)
ML ,agnetic orientation of orbitals from -l to l
Ms spin from -.5 and .5
Elec energy state
Electrons tend to occupy lowest energy state
Why do atoms bond
To reduce energy state since everything tends to low free e state
Interatomic spacing
Caused by balanced between rep and attrc forces
Attractive force
Depends on type of bond
Repulsive force
Occurs due to second atom getting too close and electron clouds interactions of two atoms
Net force of atoms
Balance of the two forces
Boeing energy
Minimum , energy when forces are balanced and net force=zero and is the amount of energy required to break the bond
Higher mean higher strength and melting point
Ionic bonds bonding energy
Strong bonds therefore strong bond energy 600-1500
How do ionic bonds attract each other
Through coulombic forces
During ionic bonding what happens to the ions
Anions same
Cations shrink
When to elements are close to each other what bond are they most likely to make
Covalent
Strength of cb
Can be strong or weak if strong don’t distort I
Easy
To back and review
Energy and force graph
Types of bonds
Dipoles
Rs btweeen melt tmp and bonding energy
Increase as Eo increase
Rs btweeen elastic modulus and bonding energy
Increase as Eo increase
Rs btweeen thermal expansion and bonding energy
Increasesa as Eo decrease
How do can appear
Weak even tho strong
Hybridization
Hybridization, which is mixing of atomic orbitals, occurs in covalently bonded elements
