2.2.2 structure and bonding
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an ionic bond is…
a strong electrostatic force of attraction between oppositely charged ions
state and describe the structure of ionic compounds
giant ionic lattice where the positive ions attract the negative ions and are surrounded by them and vice versa
state and explain whether ionic compounds have a high or low melting and boiling points
high, the attraction between ions is very strong which means lots of energy is needed to overcome this force
state and explain the conduction of ionic compounds in both solid and liquid states
when solid there are no free ions to conduct electricity so the compound is a poor conductor when molten the ions are free to move and conduct electricity so the compound is a good conductor
a covalent bond is…
a shared pair of electrons (the strong electrostatic force of attraction between a shared pair of electrons and the nuclei of the bonded atoms)
a dative covalent bond is…
formed when the shared pair of electrons in a covalent bond come from only one of the bonding atoms
a dative covalent bond could also be called…
co-ordinate bonding
give the names of the two covalent structures
giant covalent / macromolecular simple molecular
describe the simple molecular structure
individual molecules with weak forces between them with atoms being joined by covalent bonds
state and explain wether simple molecular substances have a high or low melting and boiling points
low, there are weak London forces between molecules that need little energy to overcome
describe a giant covalent structure
lattice structure in which all atoms are joined to others by covalent bonds
state and explain whether simple molecular substances are good or poor conductors
poor, there are no free electrons to move and conduct electricity
state and explain whether giant covalent substances have high or low melting and boiling points
high, strong covalent bonds need lots of energy to overcome
state and explain whether giant covalent substances are poor or good conductors
poor, in most giant covalent substances there are no free electrons that can move and conduct electricity except in graphite where there are 3 carbon to carbon bonds with each 4th outer electron being able to move and conduct electricity
explain why graphite is malleable
graphite is formed in layers that are able to slide over each other easily
a metallic bond is…
the electrostatic force of attraction between positive metal ions and a sea of delocalised electrons
state and describe the structure of metallic substances
giant metallic, lattice structure of metal ions with outer shell electrons free to move through structure
state and explain whether metallic substances have high or low melting and boiling points
high, there is strong electrostatic force of attraction between the positive metal ions and sea of delocalised electrons that means lots of energy is needed to overcome this
state and explain whether metallic substances are poor or good conductors
good, the sea of delocalised electrons are free to move through the structure and conduct electricity
explain why metallic substances are malleable
the positive ions are all identical and formed in layers that allow the ions to slide easily over one and other
from highest to lowest order the following by their repulsion • lone pair to bond pair • bond pair to bond pair • lone pair to lone pair
highest lone pair to lone pair lone pair to bond pair bond pair to bond pair lowest
each lone pair reduces the bond angle by…
2.5°
name the shape of a molecule with 2 bond pairs and 0 lone pairs and give the bond angle
linear 180°
name the shape of a molecule with 3 bond pairs and 0 lone pairs and give the bond angle
trigonal planar 120°