Unit 1 - Bonding and Structure Flashcards
Are the electrons shared equally in a pure covalent bond?
Yes
What causes London Dispersion Forces?
Imbalanced electrons cause momentary and small positive and negative charges
What do we call the charges caused by LDF?
Temporary Dipoles
Does Hydrogen bonding cause temporary or permanent dipoles?
Permanent Dipoles
Are London Dispersion Forces easily broken and what element and compounds can they be found?
Yes - all elements and compounds can show LDF. It causes low melting and boiling points
What are the diatomics?
Hydrogen, nitrogen, oxygen, fluorine, chlorine, iodine, bromine.
What is not broken when water turns from ice into water and into steam
Covalent bonds
What are elements that can bond in a covalent network structure?
Carbon, Boron and Silicon
Why is graphite a conductor of electricity?
Unlike diamond the carbon atoms in graphite are only bonded three times. This leaves a mobile electron (delocalised electron) to conduct electricity which is found in-between the graphite layers.
What are intramolecular bonds?
Bonds which join atoms within the molecule.
What are intermolecular bonds?
Bonds which join between molecules.
What structure do ionic compounds form?
Three dimensional lattices.
What 2 structures can covalent compounds have?
Discreet molecules and networks
When there is little difference in electreronegativities between atoms bonding what is produced?
A pure covalent bond
What is the electronegativity difference where we see polar covalent bonds forming?
0.4
How are the electrons shared in a polar covalent bond?
Not equally
Why can some molecules have polar bonds but not be polar molecules?
If a molecule is symmetrical the polar bond dipoles all cancel out leaving a non-polar molecule with polar bonds
What are at opposite ends of the bonding continuum?
Pure covalent and ionic
When does hydrogen bonding happen?
When hydrogen is bonded to a VERY electronegative atom (Nitorgen, Oxygen and Fluorine)
What type of dipole is a hydrogen bond?
Permanent
Which is stronger H bonding or LDF
H bonding
Polar solvents will dissolve what types of molecules?
Polar
What could cause LDF forces to get bigger?
More electrons in the molecule
H bonding will cause melting and boiling points to …
Increase
