bonding Flashcards
Ionic bonding -
Ionic bonding is the electrostatic force of attraction between oppositely charged ions formed by electron transfer
Ionic bonding is stronger and the melting points
higher when the ions are smaller and or have higher charges
Positive ions are s
Smaller compared to their atoms because it has one less shell of electrons and the ratio of protons to electrons has increased so there is greater net force on the remaing electrons holding them more closely
The negative ions formed from groups
five to seven are larger than the corresponding atoms.
The negative ion has more electrons than the corresponding atom but the same number of protons. So the pull of the nucleus is shared over more electrons and the attraction per electron is less, making the ion bigger
Within a group the size of the ionic radii
increases going down the group. This is because as one goes down the group the ions have more shells of electrons
Covalent bonding
Is a shared pair of electrons
Dative covalent bonding
A dative covalent bond forms when the shared pair of electrons in the covalent bond comes from only one of the bonding atoms. A dative covalent bond is called co - ordinate bonding.
Draw NH4, H30, NH3BF3- covalent
DRAW
The direction of the arrow goes from the atom that is providing
the lone pair to the atom that is deficient
Metallic bonding
Metallic bonding is the electrostatic force of attraction between the positive metal ions and the delocalised electrons
Three factors that affect the strength of metallic boning -
- Number of protons, strength of nuclear attraction
- The more protons the stronger the bond
- Number of delocalised electrons per atom ( The outer shell electrons are delocalised)
- more delocalised electrons the stronger the bond
- Size of the ion
- The smaller the ion, the stronger the bond
Ionic bonding - structure -
Giant ionic lattice
covalent bonding - structure
Simple molecular - with intermolecular forces between molecules
Macromolecular - giant molecular structures
Metallic bonding - structure
Giant metallic lattice
Ionic - covalent - metallic
- melting and boiling points
Ionic - high - because of giant lattice of ions with strong electrostatic forces between oppositely charged ions
Covalent simple molecular - low because of weak intermolecular forces between molecules - van der waals
Covalent macromolecular - high - because of many strong covalent bonds in macromolecular structure. Takes a lot of energy to break the strong bonds
Metallic - high because of strong electrostatic forces between positive ions and sea of delocalised electrons
Solubility in water -
Ionic - generally good
Covalent Simple molecular - generally poor
Covalent macromolecular - insoluble
metallic - insoluble
Conductivity when solid -
Ionic - ions can’t move fixed in lattice - poor
covalent molecular simple - poor - no ions to conduct and electrons are fixed in place - localised
macromolecular covalent - diamond and sand - poor because electrons can’t move
graphite - good as free delocalised electrons between layers
metallic - good - delocalised electrons can move through the structure
conductivity when molten -
ionic - good ions can move
covalent - poor no ions
metallic - good
Do lone pairs repel less than bonding pairs
NO, Lone pairs repel more than bonding pairs and so reduce bond angles - 2.5 - per lone pair
How to explain shapes -
- state number of bonding pairs and lone pairs of electrons
- state that electrons pairs repel and try to get as far apart as possible
- if there are no lone pairs state that the electron pairs repel equally
- if there are lone pairs of electrons - state that lone pairs repel more than bonding pairs
- state actual shape and bond angle
