2.1 Flashcards
what are metals physical properties
high mp & bp
good electrical conductivity
good thermal conductivity
malleability
ductility
define delocalized electrons
electrons that are not associated with any single atom or any single covalent bond
define metallic bonding
the electrostatic force of attraction between the nuclei of metal cations and delocalized electrons
what 2 factors effect the mp & bp of metals
number of delocalized electrons
atomic radius - bigger = delocalized electrons further away so decrease in forces of attraction
why do d block metals have higher melting points
they have more delocalized electrons
how do metals conduct electricity
when a potential difference is applied across the ends of a metal delocalized electrons move towards the positive terminal creating an electrical current
what factors effect a metals thermal conductivity
- free moving delocalized electrons to pass kinetic energy
- how closely cations are packed to pass kinetic energy between them
what is ment by metals being malleable & ductile
malleability - hammered or pressed into different shapes
ductility - drawn into a wire
define ionic bonding
a regular array of oppositely charged ions extending through a giant lattic
what are the physical properties of ionic compounds and why do they have these properties
high melting temperature- strong electrostatic forces of attraction between ions
brittle- layers slide over each other and opposite charges repel
poor electrical conductivity when solid- ions are not free to move and carry charge
good electrical conductivity when molten or aqueous- ions are free to move and carry charge
soluble in water- polarity of water molecules separate the ions
define covalent bond
electrostatic force of attraction between a shared pair of electrons and the nuclei of their atoms when an atomic orbital containing a single electron from one atoms overlaps with another
what is a sigma bond
end on overlap (00)
what is a pi bond and when are they formed
sideways overlap of 2 p-orbitals
must form after a sigma bond has been formed
only exist between atoms joined by a double or triple bond
high electron density both above and below the molecule
is a sigma or pi bond stronger and why
a sigma bond is stronger because it is formed from head to head overlap so the area of overlap is larger
define bond length
the distance between nuclei of the two atoms that are covalently bonded together
