Bonding and Structure Flashcards
How do ionic bonds arise?
When the difference in electronegativity is so large that one element has a much stronger attraction for boding electrons than the other.
How do pure covalent bonds arise?
When the electronegativities of two atoms are identical and the bonding electrons are evenly shared between both atoms
How do polar covalent bonds arise?
When there is a small difference in electronegativities and the electrons are shared unequally
What is the order of the types of bonding on the bonding continuum?
Pure covalent, polar covalent, ionic bonding
What is a dipole?
A bond or molecule whose ends have opposite charges
If the shape of the molecule is symmetrical, would it be polar or non-polar?
It would be non-polar
Which liquid does the charged rod affect in the charged rod experiment?
The charge in the rod only affects the polar liquid because they contain a permanent dipole
What are intermolecular forces?
The forces between molecules
What are intramolecular forces?
The forces between atoms in a single molecule
What are the ‘Van Der Waals’ forces?
- London dispersion forces (LDF’s)
- Permanent dipole-permanent dipole (PDPD)
- Hydrogen bonding
How do London dispersion forces arise?
Due to an uneven distribution of electrons, which forms a temporary dipole. The slight charges in the dipole include opposite charges in neighbouring atoms, which are called induced dipoles.
The attraction between opposing charges are known ad LDF’s
What is the relationship between LDF’s and the number of electrons in an atom or molecule?
The more electrons there are, the stronger the LDF’s are. Larger atoms contain more electrons and therefore have stronger LDF’s between them.
What are PDPD interactions?
Additional electrostatic forces of attraction between oppositely charged ends of polar molecules (they are an addition to LDF’s)
How do PDPD interactions arise?
If a molecule has a permanent dipole, it has PDPD interactions
How does hydrogen bonding arise?
When a hydrogen atom is bonded to a strongly electronegative element such as fluorine, oxygen or nitrogen.
What is the effect of LDF’s on the melting and boiling points of molecules?
The larger the molecule, the stronger the LDF’s are, making it harder to break down bigger molecules
What is the effect of PDPD interactions on the melting and boiling points of molecules?
Polar molecules have higher boiling points than non-polar molecules due the PDPD interactions. This is because PDPD interactions are stronger than LDF’s
What is the effect of hydrogen bonding on the melting and boiling points of molecules?
Molecules containing hydrogen bonding have high melting and boiling points due to their high electronegativities
What are the types of bonding present in elements?
Covalent molecular
Covalent network
Metallic
Monatomic
What is a discrete molecule?
A covalent molecule
What molecules are covalent molecular?
- Diatomic elements: Hydrogen, Nitrogen, Fluorine, Oxygen, Iodine, Chlorine, Bromine
- Phosphorus P4, Sulphur S8, Fullerene C60
How are covalent networks formed?
When atoms join together to form a very large structure with no definite size
What molecules are covalent networks?
Carbon (as graphite or diamond), Silicon, Boron
What molecules are metallic?
All elements have a metallic lattice structure. They are also all solids at room temperature
What molecules are monatomic
The noble gases
what does the prefix ‘mono’ in monatomic tell us?
That monatomic elements contain single atoms and are not bonded to any other atoms
