structure and bonding Flashcards
(24 cards)
how are ions formed
by electron loss or gain
charge of silver ion
Ag+
charge of copper
Cu2+
charges of iron ions
Fe2+, Fe3+
charge of lead
PB2+
charge of zinc
Zn2+
charge of hydroxide
OH-
charge of ammonium
NH4+
charge of carbonate
CO3 2-
charge of sulfate
SO4 2-
charge of nitrate
NO3-
ionic bonding
the electrostatic attraction between oppositely charged ions
ionic bonding always talking about electrostatic attraction because IONS have charges
no inter/intra-molecular forces
between metal and non-metal
ionic compounds properties
high melting/boiling points: strong electrostatic bonds between ions so more energy needed to overcome bonds
larger charges on the ions leads to stronger ionic bonds so higher melting points
don’t conduct when solid: no free charge carriers able top carry charge, ions in fixed position
conduct electricity when aqueous: the ions are free to move and can carry charge
brittle: made in layers, and when moved over one another, the same forces repel each other
giant ionic lattice
a cube made of the same basic repeating units
same properties as an ionic compound (high melting/boiling point; conduct only when aqueous)
example: NaCl
covalent bonding
the electrostatic attraction of two nuclei to a shared pair of electrons
two non-metals
can have one, two or three (etc) bonds between atoms
simple molecular structures
low melting/boiling points: weak intermolecular forces that don’t take a lot of energy to overcome
therefore only found as gases or liquids at room temp
however, strong intramolecular bonds within the molecule
generally melting/boiling points increase with increasing relative atomic mass because there are more intermolecular forces which take more energy to overcome
BONDS BETWEEN MOLECULES
giant covalent structures
arranged in a lattice structure
high melting/boiling point: many covalent bonds which require a lot of energy to overcome
don’t usually conduct electricity because there are no free charge carriers (exception for graphite)
BONDS BETWEEN ATOMS
diamond
doesn’t conduct electricity: no free charge carriers as all carbons bonded to 4 other carbons
very hard: rigid covalent bonds in structure
high melting/boiling point: strong c-c covalent bonds that require a lot of energy to overcome
graphite
conducts electricity: has 1 delocalised electron per every C because all carbons bonded to 3 other carbons
soft: made of layers with weak intermolecular forces of attraction between them, so can slide easily
high melting/boiling point: strong covalent bonds in the layers which require a lot of energy to overcome
C-60 fullerene
doesn’t conduct: in each molecule every carbon is only covalently bonded to 3 others and the other electrons are delocalised, these electrons cannot jump between different molecules
soft: weak intermolecular forces
low melting/boiling points: weak inter-molecular forces
do covalent structures conduct electricity
usually not
metallic bonding
electrostatic attraction between positively charged metal ions and negatively delocalised electrons
metals
conduct electricity: metals have a sea of delocalised electrons which are free to carry charge
malleable: can be shaped, when a force is applied the layers of atoms can slide over one another
thermal conductor: when heated, the delocalised electrons gain kinetic energy, making them move faster. this transfers the gained energy throughout the material making the heat transfer very efficient.
why are alloys harder than metals?
the different sized atoms disrupts the lattices regular layers, making it more difficult for the layers to slide over one another
