structure and bonding Flashcards
chapter 2
ionic bonding
transferring electrons
-ionic compounds are held together by strong forces of attraction between their oppositely charged ions
-group 1 and 7 can form ionic compounds
-groups 2 and 6 can also form ionic compounds
covalent bonding
sharing electrons
-formed with 2 non-metals
bonding in group 1 and 7
the elements in group react with the elements in group 7. As they react, atoms of group 1, can each lose one electron to gain the stable electronic structure of a gas. This electron can be given to an atom of group 7, which then also achieves the stable electronic structure of noble gas
metallic bonding
metals closely packed together and arranged in regular layers
-positively charged metal ions held together by electrons from the outermost shell. These delocalised electrons are free to move throughout the giant metallic lattice
giant ionic structures
-have high melting points (strong forces of attraction)
-solid at room temperature
-conducts electricity when melted or dissolved in water (ions can move freely and can charge throughout the liquid)
simple molecules
-low melting and boiling points (weak intermolecular forces)
-have no overall charge
-cannot conduct electricity
giant covalent structures
-very high melting and boiling points
-graphite can conduct electricity and heat because of the delocalised electrons along its layers
-graphite has no covalent bonds between its layers, just weak intermolecular forces, meaning the layers are soft and slippery
-diamond, graphite and carbon exists as fullerene (large cage like structures)
why are alloys harder than pure metals?
the regular layers of pure metal are distorted by differently- sized atoms so the layers cant slide over eachother
shape memory alloy
if it is deformed it can return to its original shape by heating
why can metals be bent and shaped?
the layers of atoms (or positively charged ions) can slide over eachother
