Alkali Metals Group 1 + Halogens Group 7 Flashcards
Why are alkali metals highly reactive (2 reasons)
Because they only have one electron in the outer shell
And have a large atomic radius so electrons are held less strongly to thr positive nuclei (because further away from positive nucleus)
Do alkali metals have low or high boiling/melting points and explain why?
Low boiling/melting point
Because electrons in the outer shell are held weakly to the positive nuclei due to its large atomic radius
So electrostatic forces of attraction are weaker so less energy is required to break the bonds
(between the sea of delocalized electrons and the positive nuclei)
Do alkali metals have low or high densities? Can any float on water?
Low densities
Lithium, sodium potassium can float
Why do alkali metals all have similar properties
Because they have one electron in their outershell
Give two physical properties of alkali metals
Shiny when freshly cut but quickly tarnish
Soft to cut with a knife
What kind of solution do all alkali metals form with water
Alkaline solutions
What is the word equation for an alkali metal with water
Alkali metal + water —-) metal hydroxide + hydrogen
Write the balanced symbol equation for the reaction between potassium and water with state symbols
2K(s) + 2H20———) 2KOH(aq) + H2(g)
Give two properties of all metal hydroxide solutions
Aqeous
colourless
Write the balanced symbol equation with state symbols of reaction between Lithium and water
2Li(s) + 2H20(l) ——-) 2LiOH(aq) + H2(g)
Describe 4 observations from the reaction of lithium and water and explain why they happen(4)
- fizzes steadily because hydrogen is given off
- Lithium does not melt
- Relatively slow reaction
- eventually dissapears
Describe four observations from the reaction between sodium and water and explain why (3)
- Fizzes rapidly
- Melts to form a ball( because a lot of heat is released)
- ball moves across the surface (because hydrogen catches fire) and eventually dissapears
Describe 5 observations from the reaction between potassium and water and explain why (5)
- fizzes very rapidly
- Melts into a shiny ball- because a lare amount of heat is released
- dashes quickly across the surface - because hydrogen catches fire
- Burns to form a lilac flame- because a large amount of heat released
- sometimes there is an explosion
What kind of hazard could happen if alkali metal is in contact with water
Would be corrosive and could cause burns
Why are alkali metals stored in oil
To prevent them reacting with oxygen or water
Does the density increase or decrease down the group of alkali metals
Density increases
Why do alkali metals tarnish/corrode when exposed to air
Because they form metal oxides when reacted with oxygen
What does metal oxide look like on an alkali metal
A dull coating over the surface
Is rubidium less dense than water
No it is more dens
What is the word equation for the reaction between alkali metals and oxygen
Alkali metal + oxygen —-) metal oxide
What is the symbol equation for the reaction between sodium and oxygen with state symbols
4Na(s) + O2(g) ——-) 2Na2O(s)
What is the balanced symbol equation for the reaction between Potassium and oxygen with state symbols
4K(s) + O2(g) ——) 2K2O(s)
Predict the melting point, density and reaction between water of rubidium
Melting point is lower than potassium
Density is higher than potassium
Reacts more vigorously and explosively than potassium
Does the melting/boiling point of the halogens increase or decrease as you go down the group and explain why?
Melting/ boiling point increases
Because molecular mass increases
So the intermolecular forces of attraction become stronger
And more energy is required to break them
Does the reactivity of the halogens increase or decrease as you go down a group and explain why
Reactivity decreases
Because atomic radius gets larger of each atom
so forces of attraction between the positive nuclei and shared electrons are weaker
Why are halogens gases at the top of the group but solids at the bottom of the group
Because boiling and melting point increases as you go down so more energy is required to break the intermolecular forces of attraction
Are halogens good conductors of heat and electricty? Explain why
Poor conductors of heat and electricty
Because covalent substances
So no delocalized electrons
What is the physcial state at room temperature of fluorine
Gas
What is the physical state at room temperature of chlorine
Gas
What is the physical state at room temperature of bromine
Liquid
What is the physical state at room temperature of iodine
Solid
Predict what the physical state at room temperature is of astatine
Solid
What colour is fluorine at room temperature
Yellow
What colour is astatine at room temperature
Black
What colour is iodine at room temperature
Dark grey
What colour is bromine at room temperature
Dark Orange
What colour is chlorine at room temperature
Yellow- Green
What colour is iodine when heated (when its in vapour form)
Purple
Does the density of halogens increase or decrease as you go down
Density increases
What happens when a halogen and hydrogen react
A hydrogen halide is formed
What forma when a hydrogen halide is dissolved in water
an acid
Write the balanced symbol equation for the reaction between hydrogen chloride and water
HCl(g) + H2O(l)——) HCL (aq)
Write the balanced symbol equation for the reaction between hydrogen and chlorine
H2(g) + Cl2(l) ——) 2HCl(g)
What is the product of the reaction between bromine and hydrogen(in words)
Hydrogen bromide
What is the general word equation for the reaction between a halogen and a metal
Halogen + metal——-) metal halide
What does a metal halide look like
A salt
What is another word for a metal halide
An ionic salt
What type of substance is formed when a halogen reacts with a non metal
A covalent compound
Wht is the word equation between fluorine and potassium chloride
Potassium chloride + fluorine ——) potassium fluoride + chlorine
Explain why iodine is able to be displaced by chlorine
Because chlorine is more reactuve than iodine
Describe what the colour change is from the reaction between potassium chloride + fluorine
to green
Chlorine is added to a solution of a compound of another group seven element.
There was a reaction and the colour changed from green to grey
Identify the group seven element present
Iodine
What colour flame is produced when lithium burns
Red flame
What is hazadous about the halogens
All have poisonous vapours
Would you see a observe a flame when there is a reaction between lithium and water or sodium and water
No
Only if you burn to test for the gas
Describe how could you test that a solution of lithium hyrdroxide is alkaline
Use red litmus paper
It should turn blue
Why can lithium nitride not conduct electricty
Because ionic compounds can only conduct electricty when molten, so when ions are free to move
State two similarities and one difference between the reaction of lithium in water and the reaction of sodium in water
They both fizz(effervesence)
They both dissolve and dissapear
But lithium does not melt
And sodium melts into a ball
Why does LiOH turn blue on red litmus paper
Because LiOH is an alkaline solution as OH- ions are present
Chlorine reacts witn hydrogen to form hydrogen chloride. This is then dissolved in water, and a ribbon of magnesium is added
State the positive ion
And the negative ion formed
And the gas that is formed
Positive = Mg2+
Negative= Cl -
Gas= hydrogen
(Because remember that hydrogen chloride in water is hydrochloric acid and then a metal and an acid makes metal salta and hydrogen)
Suggest why there is no reason to add chlorine to lithium chloride solution
Because halogens do not react with their own halides
When chlorine reacts with potassium iodide solution, what is the substance that produces a brown colour
Iodine
When there is a displacement reaction between bromine and potassium iodide, does bromine displace iodine or does bromine disolace iodide
Bromine displaces iodine
What colour does damp litmus paper turn in chlorine gas and why
White
Becuase chlorine reacts with water to form an acidic solution which acts as a bleach
(Halogen + water = acidic solution)
Which halogen has the palest colour
Chlorine
If metal X reacts with aluminum nitrate and there is no colour change, is metal X more reactive than aluminum or less reactive
Less reactive
If i add zinc to a solution of copper nitrate, and then there is a layer of layer thin coating over the zinc, what is the substance that causes this
Copper
When magnesium reacts with an aqeous solution of silver nitrate, a redox reaction occurs.
State in terms of electrons which species is the oxidizing agent and explain why
Silver ions
Because they are being reduced and gaining electrons
So are taking them away from magnesium ions
If you add phenothalepin, to a solution of potassium hydroxide, what colour does it turn and why
Pink
Because of the presence of OH- ions
