UNIT 1 - electrical conductivity
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what is an electrical current?
a flow of charged particles (e-, ions)
what do conductors of electricity allow?
they allow an electrical current to flow through them
what do non-conductors of electricity not allow?
they dont allow an electrical current to flow through them
describe the experiment for finding out what elements conduct electricity.
connect a battery to a bulb then the bulb to an element, if the bulb glows when in contact with the element it is a conductor
what elements are electrical conductors?
metal elements and carbon in the form of graphite
what elements are not electrical conductors?
non-metals
what do the atoms share in a covalent bond?
a pair of electrons
why is there no conduction of electricity in a covalent bond?
because the electrons are not free to move around because the atoms share a pair of electrons
why do non-metals not conduct electricity?
because they do not have charged particles which can move and therefore they do not conduct electricity
what is the one electrical conductor that is a non-metal?
carbon in the form of graphite
what does carbon in the form of graphite have?
a layered covalent network structure
what does each carbon in the form of graphite atom use?
only 3 electrons for bonding, the remaining electron is delocalised over the whole structure
why can carbon in the form of graphite conduct electricity?
because the electrons are free to move between the layers therefore the electrons can flow through it
what compounds do not conduct electricity? and why?
-covalent compounds because the electrons in covalent compound are not free to move, -ionic compounds do not conduct electricity in the solid state, however they conduct when dissolved in water or when molten
why can ionic compounds only conduct electricity when dissolved in water or when molten?
because the lattice break and the ions become free to move
what may covalent molecular substances which are insoluble in water dissolve in?
other solvents
what does not dissolve?
covalent network substances
what happens as covalent molecular substances dissolve?
the lattice structure breaks up allowing water molecules to surround the seperated ions
what is a saturated solution?
it is a solution which has dissolved as much solute as it is capable of dissolving
what do ionic compounds tend to be insoluble in?
covalent solvents, like ethanol
if your writing out a word equation with the elements symbols do you need to show if they’re diatomic?
YES!!!
what is the GFM?
the mass in grams of ONE MOLE of a substance
what are the all the equations for m, n, gfm, calculations?
-(m=n x gfm) -(n=m / gfm) -(gfm=m / n)
Explain the physical properties of ionic compounds: 1.melting point and boiling point 2.solubility (water molecules surround ions) 3.electrical conductivity
• Ionic compounds have high melting and boiling points because strong ionic bonds must be broken in order to break down the lattice. • Tend to be soluble in water. • Ionic compounds conduct electricity only when molten or in solution, due to the breakdown of the lattice resulting in the ions being free to move.