Lab 10 - Chemical Bonding And Hybridization Flashcards
Types of bonds
Covalent bond
Occurs between non-metal atoms like CO₂.
Strongest type
Ionic bond
Occurs between metal and non-metal atoms like NaCl.
Metallic bond
Occurs between metal atoms only and the sea of delocalized electrons around them.
Why do atoms form bonds?
• Bonds involve the electrons in the outer shells of atoms.
• Each shell has a maximum number of electrons that it can hold.
• Electrons fill the shells nearest to the nucleus first.
• The outermost shell is called the valence shell, and electrons in the valence shell are termed as valence electrons.
• Filled electron shells are very stable.
The level of energy of the first shell
Lowest energy
Energy levels
• Also called shells, represent the main energy states of an electron in an atom.
• Each energy level is denoted by a principal quantum number n (e.g., n =1, 2, 3, etc.).
• Energy level increases as n increases (electrons are farther from the nucleus).
Sublevels (Subshells) Within Energy Level
s, p, d, and f
The type and number of sublevels within an energy level depend on the value of n:
• n=1: Only an s sublevel
• n=2: s and p sublevels
• n=3: s, p, and d sublevels
• n=4: s, p, d, and f sublevels
How many electrons can orbitals hold?
The number of orbitals in each sublevel determines the maximum number of electrons it can hold:
• s sublevel: 1 orbital, holds a maximum of 2 electrons
• p sublevel: (px, py, pz) 3 orbitals, holds a maximum of 6 electrons
• d sublevel: 5 orbitals, holds a maximum of 10 electrons
• f sublevel: 7 orbitals, holds a maximum of 14 electrons
Which is filled first the 4s or 3d sublevel?
4s sublevel fills before the 3d sublevel because it has slightly lower energy.
Shapes of the orbitals
s orbital (spherical shape)
p orbital (dumbbell shape)
d orbital (cloverleaf shape)
f orbital (complex shapes)
Octet rule
principle stating that atoms tend to gain, lose, or share electrons in order to achieve a full valence shell, typically with eight electrons (stable configuration)
Electrostatic attractions
Ionic
Charge - dipole
Dipole - dipole
Hydrogen bonding
Ionic bonding
strong electrostatic attraction between fully charged ions
Na+ and Cl− in NaCl
Charge-dipole
interactions between a fully charged ion and a polar molecule with a partial charge (a dipole).
Na+ in H₂O
Dipole-dipole
interactions occur between two polar molecules that have partial charges.
HCl (polar covalent bond)
Hydrogen bonding
Strong dipole-dipole interactions
Occur when hydrogen is covalently bonded to highly electronegative atoms (O, N, or F)
Hydrogen bonds between water molecules (H₂O
Bond strength unit
kcal/mol
Bond strength
represents the amount of energy required to break one mole of bonds in a substance
Types of overlapping
Sigma bond
Pi bond
Sigma bond
Formed by the end to end (head-on) overlap
Pi bond
Formed by the side wise overlap
Hybridization
Process of intermixing of the orbitals of slightly different energies
Types of hybridization
sp
sp2
sp3
sp3 hybridization
one s-orbital and three p-orbitals to form four equivalent sp3 hybridized orbitals.
Tetrahedron
109.5°
CH4
sp2 hybridization
one s and two p-orbitals in order to form three equivalent sp² hybridized orbitals.
Trigonal planar
120°
C2H4
sp hybridization
one s and one p orbital resulting in the formation of two equivalent sp hybrid orbitals.
Linear
180°
C2H2
