topic 2 - ionic compounds Flashcards
what is ionic bonding?
a transfer of electrons.
what happens in ionic bonding?
atoms transfer (lose or gain) electrons to form pos. or neg charged atoms called ions.
what groups are most likely to form ions?
1,2,6,7
what do groups 1 & 2 do?
they are metals and lose electrons to form cations.
what do groups 6 & 7 do?
they are non-metals and gain electrons to form anions.
what groups form ionic bonds?
ionic bonds only form when opposites sides of the periodic table join so cations and anions will form ionic bonds.
what do ionic bonds always produce?
compounds with similar structures.
what do ions form? and why?
a closely packed lattice structure.
because ionic bonds are very strong electrostatic forces of attraction between opposite charges.
why do ionic compounds have high melting and boiling points?
due to strong bonds between ions, therefore it takes a lot of energy to break these bonds.
why do ionic compounds conduct electricity when aqueous or molten?
when in aqueous solution, ions separate and are free to move: so will carry electric currents.
The same happens when they melt and the ions are free to move and will carry electric currents.
Common carbonates and hydroxides are insoluble except what?
sodium, potassium and ammonia.
what is a precipitation reaction?
is when soluble substances in solutions react to form an insoluble precipitate.
what is the method for a precipitation reaction?
- add a spatula of lead nitrate to a test tube and fill it with distilled water.
- shake to ensure all lead has dissolved and do the same with the sodium chloride.
- tip 2 solutions into a small beaker and give a good stir to make sure its all mixed.
- the lead then should precipitate out.
- put a folded piece of filter paper into a funnel and stick into a conical flask.
- pour the contents of the beaker onto filter paper.
- swill out the beaker with more distilled water and tip into the filter paper.
what is a barium meal?
barium sulfate is given to patients to help diagnose if they have problems in their intestine.
the patient swallows a drink called barium meal which contains barium sulphate.
barium salts are toxic, however the drink is safe to swallow because barium sulphate is insoluble so cannot enter the blood stream.
how do you carry out a flame test?
dissolve salt in water.
dip the wire rod into HCL and then into the flame.
dip the wire into salt and put in the flame, the colour should of dissolved.
