Topic 6 - Groups in the Periodic Table Flashcards
What are group 1 elements know as?
The alkali metals
What are the properties of group 1 metals?
Low mp/bp
Very soft
How reactive are group 1 metals?
Very reactive
What determines a metals reactivity?
How readily it loses its outer electron
What is the trend of reactivity for group 1?
As you go down, it gets more reactive
What happens when alkali metals are put in water?
They react vigorously
What is the word equation for the reaction between water and alkali metals?
Alkali Metal + Water -> Metal Hydroxide + Hydrogen
How do test for the presence of hydrogen gas?
By a lit splint making a squeaky pop
Describe the observations when lithium is put into water?
It will move around the surface, fizzing furiously
Describe the observations when sodium is put into water?
It will move around the surface, fizzing furiously whilst also melting due to the heat of the reaction
Describe the observations when potassium is put into water?
It will move around the surface, fizzing furiously whilst also igniting the hydrogen gas produced
Write a balance symbol equation for the reaction between potassium and water
2K + 2H2O -> 2KOH + H2
What are group 7 elements known as?
The halogens
What do the halogens exist as?
Diatomic molecules
What do you notice as you go down the halogens?
The melting points and boiling points increase
Colour gets darker
Describe chlorine
A fairly reactive, poisonous, green gas
Describe bromine
A poisonous, red-brown liquid, which gives off an orange vapour at room temperature
Describe iodine
A dark grey crystalline solid which gives off a purple vapour when heated
How do you test for chlorine?
By holding a piece of damp blue litmus paper which will bleach if chlorine is present, turning it white
It may also turn red for a moment first
What is the trend of reactivity for halogens?
Decreases as you go down
What is the word equation between metals and halogens?
Metal + Halogen -> Metal Halide
What do metals and halogens react to form?
Metal halides
What are metal halides?
Salts formed when halogens react with metals
What is the word equation between hydrogen and halogens?
Hydrogen + Halogens -> Hydrogen Halide
Write a balanced symbol equation for the reaction between bromine and sodium?
Br2 + 2Na -> 2BrNa
What is a displacement reaction?
Where a more reactive element displaces a less reactive element from a compound
What type of reactions are halogen displacement reactions?
Redox
Why are halogen displacement reactions redox?
Because halide ions lose electrons whilst halogens gain elecrons
A student adds a few drops of a halogen solution to a potassium iodide solution
The solution turned brown
Explain what the student should do to help him identify the halogen solution
He should add a few drops of the solution to a bromine salt solution
If the solution turns orange, the halogen solution contains chlorine
What are group 0 elements?
Inert and colourless gases
What are group 0 elements called?
Noble gases
What does monatomic mean?
They are gases made up of single atoms
Are noble gases diatomic or monatomic?
Monatomic
What are the properties of the noble gases?
Monatomic
Inert
Colourless
Non-flammable
What are the uses of noble gases?
Stopping burning in filament lamp
Welding in metals
Airships
Balloons
Why are noble gases used in filament lamps?
Because they’re non-flammable
Why does helium float?
Because it’s density is lower than air
Why is helium used over hydrogen?
Because hydrogen is extremely flammable
What is the trend as you go down the noble gases?
Boiling point, melting point and density all increase
Use the densities off helium (0.2 kg/m³) and argon (1.8 km/m³) to predict the density of neon
(0.2 + 1.8) / 2 = 2.0 / 2 = 1
Neon should have a density of about 1.0 kg/m³
Give two properties of the group 1 metals?
Low mp/bp
Very soft
Explain why group 1 metals are so reactive?
Because all group 1 metals have only 1 outer electron meaning there is only 1 electron that needs to be lost meaning it is very reactive
Put all these alkali metals in order of reactivity, staring with the least reactive:
Potassium, Caesium, Lithium and Sodium
Lithium, Sodium, Potassium and Caesium
How many electrons do halogens have in their outer shell?
7
Why can halogen displacement reactions be described as redox reactions?
Because halogens gain electrons whilst the halide ions lose electrons
If chlorine water is added to potassium bromide solution, what colour will the solution turn?
Orange solution formed
At room temperature, what colour are the Group 0 gases?
Colourless
Why are balloons filled with helium able to float in the air?
Because helium has a lower density than air meaning it will float
