Bonding Flashcards
(34 cards)
What is ionic bonding
Strong electrostatic forces of attraction between oppositely charged ions held in a lattice
How high are ionically bonded substances bp and mp and why?
High - takes alot of energy to break strong electrostatic forces of attraction between oppostiely charged ions
Do ionic compounds conduct electricity
Yes - when molten as the ions are free to move and carry a charge ( not when solid)
What is simple molecular covalent bonding
Strong covalent bonds between atoms, weak van der waal forces of attraction between molecules
Are there are lone electrons in simple covalent bonding?
No - all involved
Can simple molecular covalent molecules conduct electricity and why?
No - all electrons used in bonding arent free to move
do simple molecular substances have a high/ low mpt and bpt. Why?
Low - weak van der waal froces of attraction between molecules that dont take much energy to overcome
Describe macromolecular covalent bonding
Lattice of many atoms held together by strong covalent bonds.
Do substances with macromolecular covalent bonds have high/ low mpt and bpt and why?
High as it takes alot of energy to overcome strong covalent bonds
Do substances with macromolecular covalent bonds conduct electricity
Most dont as all alectrons used in bonding
describe the structure of diamond
3D tetrahedral structure of C atoms with each C atom bonded to 4 others
describe the structure of graphite
- each C atom is only bonded to 3 others so it is in layers
- weak van der waal forces of attraction between layers mean they can slife over each other - soft, slippery
- one electron from each carbon atom is delocalised and can carry charge - conducts electricity.
describe metallic bonding
Lattice of positive metal ions strongly attracted to a sea of delocalised electrons.
Latyers can slide over each other - malleable
Do metallic compounds have high/low bpt and mpt and why?
High as strong forces of attraction between positive metal ions and negatively charged sea of delocalised electrons
Do metallic compounds conduct electricity and why?
Yes as delocalised electrons can move throughout the metal to carry charge
How does the strength of metallic bonds change across the periodic table and why
Increases - so higher melting and boiling points = stronger
- higher charge on metal ions
-more delocalised electrons per ion
-stronger force of attraction between them
what is electronegativity
the power of an atom to attract a bonding pair of electrons in a covalent bond
What affects electronegativity
Nuclear charge
Atomic radius
electron shielding
How do you get a nonpolar bond
Both bonding elements have the same electronegatives
When do you get a polar bond
Bonding atoms have different electronegatives
Describe how van der waals arise
- temporary dipoles are created by the random movement of electrons
- induces dipole in neighbouring molecule
- temporary induced dipole dipole attraction aka van der waals forces of attraction
Are van der waal forces greater in smaller or larger mols
larger - more electrons
Describe dipole dipole attraction
Some molecules with polar bonds have permanent dipoles
forces of attraction between those dipoles and those of neighbouring mols
what conditions are needed for H bonding to occur
H bonded to NOF
Because NOF are highly electronegative
strong force of attraction between H nucleus and lone pair of electrons on NOF
