Predicting & Identifying Reactions & Products Flashcards
What are the group 1 elements known as?
alkali metals
What are 3 properties of alkali metals?
soft
low density
low melting point
very reactive
Why are alkali metals so reactive?
they have 1 electron in their outer shell which is really easy to lease, making it easier for them to reactive
As you go down group 1, the elements:
get more reactive
have lower melting and boiling points
Why are the lower alkali metals so reactive?
their valence shell is much further than the higher metals, meaning that their electron can be more easily lost.
Alkali metal + water ➔
metal hydroxide + hydrogen
What are the group 7 elements called?
halogens
What are the group 0/8 elements called?
noble gases
What do halogens exist as?
diatomic molecules
As you go down group 7, the elements:
melting and boiling point increase
reactivity decreases
Why are the lower halogens less reactive?
halogens need to attract electrons to achieve a full outer shell, but the lower halogens’ valence shell is further away and therefore has weaker forces of attraction
What are halogen displacement reactions?
the more reactive halogen displaces the less reactive halogen
Cl2 + 2KBr ➔
Br2 + 2KCl
what is the main property of noble gases?
they are inert as they have full outer shells
As you go down group 0, the elements:
boiling and melting points increase
Fluorine is a _____ _____ coloured gas and is the _____ reactive halogen
poisonous, yellow, most
Chlorine is a _____ coloured gas.
green
Bromine is a _____-_____ _____ liquid which is also _____ .
red-brown, volatile, poisonous
Iodine is a _____ coloured solid with _____ vapours.
grey, purple
Are noble gases flammable?
no
Sodium reacts with water to produce sodium hydroxide and a gas.
What is the name of the gas produced?
hydrogen
What would happen if iron and lithium sulfate were mixed together?
nothing
What is the order of the reactivity series?
potassium
sodium
lithium
calcium
magnesium
aluminium
carbon
zinc
iron
tin
lead
hydrogen
copper
Do metals react more vigorously with acid or water?
acid
What is the test for chlorine gas?
expose it to blue litmus paper, which will then turn red and bleach white if chlorine is present
What safety precautions are required for testing chlorine gas?
wear a gas mask
do the experiment in a fume cupboard
How do you test for oxygen gas?
expose it to a glowing splint, which will relight if oxygen is present
How do you test for hydrogen gas?
expose it to a lit splint, which will create a squeaky pop if hydrogen is present
How do you test for carbon dioxide gas?
bubble it through limewater, which will turn cloudy white if carbon dioxide is present
How do you test for carbonate ions?
1) add dilute HCl to sample
2) bubble the produced gas through limewater
3) if limewater goes cloudy, CO2 was produced, therefore, carbonate ions are present
How do you test for sulfate ions?
1) add dilute HCl to the sample
2) Add barium chloride solution
3) if white precipitate forms (Barium sulfate) sulfate ions are present
Why do we add HCl to the sample when testing for sulfates?
to remove any carbonate or sulfite ions. These ions can react with barium ions to form a white precipitate giving us a false positive
How do you test for halide ions?
1) add dilute nitric acid to sample
2) add silver nitrate
if chlorides are present, white precipitate is formed
if bromides are present, cream precipitate forms
if iodides are present, yellow precipitate forms
Why do we add nitric acid to the sample when testing for halides?
to remove any carbonate or sulfite ions. These ions can react with silver ions to form a white precipitate giving us a false positive
What are the 2 groups of tests for cations?
the flame tests
the metal hydroxide tests
how do you conduct a flame test?
Take a nichrome wire loop, and clean it by dipping it in some dilute hydrochloric acid, rinsing it in distilled water, and then heating it over a Bunsen burner flame.
Dip the wire loop into the compound you want to test.
Hold the wire loop in the clear blue part of the Bunsen burner flame (this is the hottest part).
See what colour the flame turns as the compound burns.
What are the flame colours for lithium, sodium, potassium, calcium, copper ions?
red, yellow, lilac, orange, green
What is a limitation of the flame test?
if you have 2 or more different metals in your sample, then the colours of the flames will mix together, and you probably won’t be able to tell which metals you have.
How do you conduct the metal hydroxide test?
react the cation with sodium hydroxide. The colour of the precipitate and solution tells us which cation is present
What precipitates do copper (ll), Calcium, iron (ll), iron (lll), and zinc ions produce?
blue, white, green, brown, white
How would you tell if calcium ions are present or zinc ions?
add excess NaOH until one of the solutions re-dissolves to form a colourless solution. The colourless solution has zinc ions
