Bonding, structure and properties Flashcards
Metallic bonding
the electrostatic force of attraction between positively charged ions and (negatively charged) delocalised outer electrons.
How are atoms in covalent bonds held together?
By the electrostatic forces of attraction between positively charged nuclei and the negatively charged shared electrons
What does the polarity of a covalent bond depend on?
On the difference in electronegativity of the bonded atoms
Ionic bonding
electrostatic force of attraction between positively and negatively charged ions.
what causes Van der Waals?
Electrostatic attraction between temporary dipoles and induced dipoles caused by movement of electrons in atoms or molecules.
Describe Van der Waals forces
Can operate between all types of molecules and atoms.
Are the weakest of all the other types of bonding.
Their strength depends on the sizes of the atoms or molecules.
polar molecule:
molecule with a permanent dipole.
what are permanent dipole-permanent dipole interactions?
they are additional electrostatic forces of attraction between polar molecules. they are stronger than VDW forces between molecules of the same size.
the spatial arrangement of polar covalent bonds results in a molecule being…
polar.
Between what elements can hydrogen bonding occur with?
Nitrogen, oxygen and fluorine
Describe hydrogen bonding
Stronger than permanent dipole-permanent dipole interactions but weaker than covalent.
(el.st. forces of ) Attraction between molecules which contain highly polar covalent bonds.
Describe a metallic structure
Lattice of positive ion and delocalised electrons
Describe covalent molecular structure
Discrete molecules held together by weak intermolecular forces.
Describe covalent network structure
A giant lattice of covalently bonded atoms.
Describe ionic molecular structure
A giant lattice of oppositely charged ions.
Describe monatomic structure
Discrete atoms held together by VDW forces.
what does it mean if a molecule is discrete (don’t need to know for exam)
it is held together by VDW forces.
compare melting and boiling points of polar molecules to those of non polar molecules.
The melting/boiling points are higher for polar molecules.
What can these be related to?
- melting/boiling points
- hardness/softness
bonding and structures of elements
What compounds are soluble in polar solutions such as water?
Polar molecular and ionic compounds.
what is not soluble in water or polar compounds, but is in non-polar solutions?
Non-polar compounds.
Give examples of anomalous boiling points due to hydrogen bonding.
Ammonia, water and hydrogen fluoride.
Give 4 properties of compounds that are affected by hydrogen bonding.
higher boiling points and melting points, greater viscosity and miscibility with water.
Why is the density of ice less than that of water?
Hydrogen bonding results in tunnels forming in the structure which are full of air.