Bonding Flashcards
Define ion
a charged atom
Define ionic bond
the electrostatic force of attraction between oppositely charged ions
Describe the structure of an ionic structure
ionic bonds have a lattice structure and the ions are arranged in a regular pattern
Properties of ionic compounds
- high melting and boiling point (strong electrostatic forces of attraction)
- brittle (ionic crystals can split apart)
- soluble in water (can form ion-dipole bonds)
- conduct electricity when molten or dissolved (ions are free to move)
- low volatility (strong ionic bonds, lot of energy required)
covalent bond
the electrostatic force of attraction between a positively charged nuclei and a pair of electrons
Relationship between bond length and bond strength
bond length decreases as there are more electron pairs involved, causing greater attractive forces between the 2 nuclei and the bond strength increases because more energy is needed to break them
How does electronegativity relate to the type of bond
- big electronegativity difference <2 (ionic bond)
- small electronegativity difference 1 – 2 (polar)
- no difference in electronegativity <1 (non-polar)
Properties of simple covalent structures
- low melting and boiling point (weak IMFs)
- doesn’t conduct electricity (no free ions or electrons)
- insoluble if non-polar, soluble if polar
- high volatility (weak IMFs)
What affects the polarity of a molecule
- the electronegativity difference
- the symmetry of the bonds
What are the properties of non-polar and polar molecule
polar: difference in electronegativity, asymmetrical structure
non-polar: polar bonds cancel out
How to draw a lewis structure
1) count the total number of valence electrons
2) determine the central atom (furthest from F)
3)Put all the remaining valence electrons as lone pairs
4)Count the total number of valence electrons
Who has incomplete octets
Be and B
Who can expand their octets
elements of period 3 and below
Examples of resonance structures
carbonates, benzene, ozone,
Vesper Theory
- all electron pairs and all lone pairs arrange themselves as far apart
- Lone pairs repel more strongly than bonding pairs
- multiple bonds behave like single bonds
What is the structure and bond angle for 2 bonding pairs
linear + 180°
ex: CO2 or BeCl2
What is the structure + bond angle for 3 bonding pairs
trigonal planar + 120°
ex: BF3
bent + <120° (118°) – (1lone pair)
ex: SO2
What is the structure and bond angle for 4 bonding pairs
tetrahedral + 109.5°
ex: CH4, NH4+
trigonal pyramidal + <109.5° (1 lone pair)
ex:NH3
bent + <109.5° (2 lone pairs)
ex:H2O
What is the structure and bond angle for 5 bonding pairs
trigonal bipyramid + 90°&120°
ex:PCl5
seesaw + 90°&<120° (1 lone pair)
ex: SF4
T-shaped + 90° (2 lone pairs)
ex: ClF3
linear + <180° (3 lone pairs)
ex: I3-
What is a resonance structure
it involves (delocalised) electrons being shared between more than one bonding position