topic 2 Flashcards
what kind of structure do ionic compounds have?
closely packed regular lattice structure
ionic bonds have very strong…
electrostatic forces of attraction between oppositely charged ions
what are the 2 main properties of ionic compounds?
they have high melting and boiling points
they conduct electricity when aqueous or molten
when do inimical compounds conduct electricity?
when aqueous or molten
do I ionic compounds have high or low melting and boiling points?
high
why do I ionic compounds have high melting and boiling points?
they have strong electrostatic forces of attraction between oppositely charged ions so it takes a lot of energy to break these bonds
why do ionic compounds conduct electricity when aqueous?
the ions speedster and are all free to move so they can carry an electrical current
what diagrams are used to show inimical compounds?
dot and cross diagram
why do ionic compounds conduct electricity when molten?
the ions are free to move so they can carry and electrical current
what are the two rules when naming compounds?
1) when two different elements combine the compounds name is something ‘ide’
2) when 3 or more different elements combine and one of the is oxygen the compounds name is something ‘ate’
how do you make a pure, dry sample of an insoluble salt?
use a precipitate reaction
is barium sulphate an insoluble salt?
yes
what are the steps of a precipitation reaction?
1) mix the two solutions together
2) filter out the precipitate
3) wash it with distilled water to wash impurities off the precipitate
4) dry it on filter paper
give a use of barium sulphate
x - Rays
barium meal
why do we use barium sulphate for x rays?
it is opaque to x rays so when you drink it it shows up the gut so that any problems can be seen
barium salts are toxic so why can you safety drink barium sulphate?
it’s insoluble so it isn’t absorbed into the bloodstream
what colour flame is: sodium potassium calcium copper
yellow/orange
lilac
brick-red
blue-green
how do you conduct a flame test?
1) dip a clean fire loop into a compound
2) put the wire loop in the clear blue part of the Bunsen flame
how do you make sure the wire loop is clean when doings flame test?
dipping it into hydrochloride acid and rinsing it with distilled water
what do you do if you’re using a powered solid when doing a flame test?
dip the wire loop in hydrochloric acid to moisten it before dipping it in the solid so that some of the solid sticks to the wire
what is a spectroscopy used for?
to identify elements in a sample
what are positives of using spectroscopy?
it’s fast, reliable and can be used with vey small amounts of elements in a sample
how does a spectroscopy work?
a little like the flame test, the patterns of light emitted by the elects in a heated sample are analysed
how do you test for carbonates? testing to see if a gas is carbon dioxide
by bubbling it through limewater and if carbon dioxide is present then the limewater turns milky
