topic 6 groups in the periodic table Flashcards
what are group 1 metals known as
Alkali Metals
how many outer electrons do group 1 elements have
1 so they have similar chemical properties
what are the physical properties of group 1
low melting points and boiling points compared to other metals
very soft- they can be cut with a knife
what do alkali metals form
ionic compounds. they lose their single outer electron so easily that sharing it is out of the question, so they don’t form covalent bonds
do group 1 metals get more or less reactive as you go down
more reactive
why is the outer electron more easily lost
because its further from the nucleus (the atomic radius is larger) - so its less strongly attracted to the nucleus and less energy is needed to remove it
what happens when alkali metals are put in water and what is produced
they react vigorously, hydroxide and hydrogen gas
what is the equation for sodium and water
sodium + water -> sodium hydroxide + hydrogen
2Na+ 2H2 -> 2NaOH + H2
what happens to Lithium, sodium and potassium when put in water
-lithium will move around the surface, fizzing furiously
- sodium and potassium do the same, but they also melt in the heat of the reaction. Potassuim even gets hot enough to ignite the hydrogen gas being produced
what are group 7 elements known as
Halogens
how many electrons do halogens have in their outer shells
7
what happens as you go down group 7
the melting points and boiling points increase
what happens as you go down group 7
the melting points and boiling points increase
what are chlorine, bromine and iodine at room temperature
- Chlorine is a fairly reactive, poisonous, green gas
-Bromine is a poisonous, red-brown liquid which gives off an orange vapour at room temp
-Iodine is a dark grey crystalline solid which gives off a purple vapour when heated
how do you test for chlorine
hold a piece of damp blue litmus paper over it, chlorine will turn it white
what happens to reactivity as you go down group 7
it decreases- it gets harder to attract the extra electron to fill the outer shell when it’s further away from the nucleus
what happens when halogens react with some metals
they form salts called ‘metal hallides’
what happens when halogens react with hydrogen
they form hydrogen hallides which are soluble and can dissolve in water to form acidic solutions
what type of reaction do halogens take part in
displacement reaction- a more reactive element pushes out a less reactive element from a compound
why are the halogen displacement reactions redox reactions
the halogens gain electrons ( reduction) whilst halide ions lose electrons (oxidisation)
what is the equation for the displacement reaction of chlorine and potassium bromide
chlorine+ potassium bromide -> bromine + potassium chloride
Cl2 + 2KBr-> Br2 + 2KCl
how do you use displacement reactions to show the reactivity trend of the halogens
-measure out halide solution in a small tube and add a few drops of a halogen solution and shake the tube gently
-if you see a colour change, then a reaction has happened
-REPEAT using different combinations
what happens to the potassium chloride solution for all the halogen solutions
no reaction :(
what happens to the potassium bromide solution when the halogen solutions are added
orange solution formed when chlorine water added, no reaction for bromine or iodine
what happens to the potassium iodide solution
brown solution formed from the chlorine and bromine waters, no reaction for the iodine water
what are the group 0 elements called
noble gases
what are the noble gases at room temp
colourless gases
what does the fact that noble gases are monatomic mean
they are only made up of single atoms
why are the noble gases inert, and non flammable
they have a full outer shell of electrons
what are the uses for argon
provides an inert atmosphere in filament lamps (light bulbs) as it stops the hot filament from burning away. Also used in flash photography as well as krypton and xenon, used to stop the flash filament from burning up
which noble gases can be used to protect metals that are being welded
argon and helium, the inert atmosphere stops the hot metal reacting with oxygen
what is helium used for
airships and party balloons as it has a lower density than air, its also no flammable so which makes it safer to use than hydrogen gas
what happens to the bp, mp and density as you gown the group 0
they increase
