Topic 6 - Groups in the Periodic Table Flashcards
Why do the elements in Group 1 have similar chemical properties?
They all have 1 outer electron
What is Group 1 called?
Alkalai Metals
What are the Group 1 Physical Properties
Low melting and boiling points ( comp to other metals)
Very soft
What bonds do Group 1 elements form?
Ionic, no covalent bonds
Why doesnt group 1 form covalent bonds?
They only have 1 outer electron so it is lost very easily, there is no point of sharing it
What ions do group 1 form?
+1
What makes a metal reactive?
the more readily a metal looses their outer electrons, this makes group 1 ( with only 1 outer electron ), very reactive
Why are metals more reactive with water ( or dilute acid ) as you go down a group?
Their outer electrons are further out, having more shells in between them. This makes the electron less strongly bonded the the nucleus and less energy is needed to remove it.
What happens when Alkali Metals (group 1) react with water?
A hydroxide and a hydrogen gas
They react vigorously, forming an ionic compound
Write the balanced equation for sodium reacting with cold water
2Na + 2H₂O –> 2NaOH + H₂
Sodium + water —> Sodium hydroxide + water
Lithium’s reaction with water
Move around the surface, Fizzing furiously
Sodium and Potassium reactions with water.
Same as lithium, but they also melt in the heat of the reaction.
Potassium often gets hot enough to ignite the hydrogen produced.
WHat are group 7 elements known as?
Halogens
Why do group elements have similar properties?
They all have the same number of outer electrons
How do halogens exist chemically?
In Diatonic Molecules, sharing one pair of electrons in a covalent bond giving both atoms a full outer shell
What are the physical properties of Group 7 elements?
The melting and boiling points increase as you go down the group
Why do the melting/boiling points increase as you go down group 7 molecules?
The Molecules get bigger due to more shells, this creates stronger intra-molecular forces meanign more energy is needed to break them apart
What is Chlorine at room temperature?
a fairly reactive, poisonous, green GAS
What is Bromine at room temperature?
a poisonous red-brown liquid, which gives off an orange vapour at room temperature.
What is iodine at room temperature?
a dark grey crystalline solid which gives off a purple vapour when heated.
How do you test a gas for Chlorine?
Damp Blue Litmus Paper
- Chlorine will bleach the litmus paper, turning it white.
- ( it may turn it red first as it is acidic)
How does reactivity work in Group 7?
It is less as you go down the group.
Halogens need to gain an electron, as more shells are gained the attraction to the nucleus is less, making it harder to attract and electron.
What makes a Halogen reactive?
the Easier it is to attract an electron
What is the reaction of Halogens with metals?
Halogen + Metal –> Metal Halide (Salt)
Why are halogens higher in the group more reactive with metals?
The attract the outer shell of the metal more easily.
What is the reaction of halogens and Hydrogen?
Halogen + Hydrogen -> hydrogen halides
Properties of hydrogen halides?
Soluble, and can dissolve in water to form acidic solutions.
Hydrogen chloride -> Hydrochoric acid
What is a displacement reaction?
Where a more reactive element displaces a less reactive element from a compound
What are halogen displacement reactions?
Redox reactions
WHat happens in a halogen displacement reaction?
The halogens gain electrons, whilst halide ions loose electrons
A higher period halogen will displace the halide
Why does the solution turn orange when chlorine reacts with potassium bromide
the chlorine displaces the bromide and the bromine is released therefore turns the solution orange
Displacement reactions halogens experement
Mesure out a small amount of halide salt solution into a test tube
Add a few drops of halogen solution to it and shake it gently
If a color change is observed, a reaction has happened
reactivity in halogens
less reactive as you go down the group
What are the group 0 elements called?
Noble gases
What are noble gases typical features at room temp
colourless gases
monatomic
inert - dont react alot (full outer shell of electrons)
non-flammable
hard to observe
Uses of noble gases
- used to provide an inert atmosphere
- Argon in filament lamps
- Argon and helium in welding
- Helium in airships (lower density than air) - non flammable so better than hydrogen
Argon in filament lamps
non-flammable, so stops filament from burning away
( same principle for flash photography)
Argon and helium in welding
Protecting metals whilst welding, inert atmosphere protects the hot metal from reacting with the oxygen
Trends in properties of noble gases
Boiling point, melting point and density all decrease as you go down the group
