Periodic table Flashcards
Another name for Group One elements
alkaline metals
Why does the reactivity increase as you go down group one?
As you go down group one the atoms get bigger so the outer electron will get further away from the nucleus. This means that the attraction from the nucleus becomes less, so the electron becomes more easily lost and so the metals become more reactive towards the bottom of group 1.
⬇ group 1
atom gets bigger
outer electron = further away from nucleus
attraction nucleus = less : electron = more easily lost : metals = more reactive ⬇ group 1
Structure of reaction when Group One metal (Li) reacts with water
2 Li(s) + 2 H2O → 2 LiOH (aq PH – 13/14 Alkaline) + H2(g)
Why are Group One metals kept in oil?
to protect them from reacting with the oxygen in the air
Description of Group One reaction with water
- Fizzing
- Moving
- Spitting
- Floating
- Coloured flame
What do you see when a fresh piece of a Group One metal is cut?
shiny as a metal
physical properties of Group One metals:
- Hardness- soft and can be cut by knife
- Low melting and boiling point
- softness increases as you go down the group
Colour + state of chlorine
Pale green, yellow gas
colour + state of bromine
dark orange liquid
colour + state of iodine
dark grey solid
Test for chlorine
if chlorine gas is present then damp blue litmus paper should be turned red then bleached white
Why does the reactivity increase as you go up group 7?
As you go down group 7 the atoms get bigger so the outer electron will get further away from the nucleus. This means that the attraction from the nucleus becomes less, so the electron becomes harder to gain and so the metals become more reactive towards the top of group 7.
Displacement reactions involving halogens
in these reactions are more reactive halogen will displace the less reactive halogen from the compound
eg chlorine + sodium bromide -> sodium chloride + bromine
Physical properties of the halogens
- exist as diatomic molecules
- melting and boiling point increases as you go down the group because intermolecular forces get stronger due to more points of contact.
why are the noble gases unreactive
They have a full outer shell of electrons making them not want any electrons making them unreactive.
Helium uses
- Used it airships as it’s less dense than air
- Used in oxygen tubes for deep sea divers
- used in neon signs
neon uses
used in neon signs- when an electric current is passed through it – it glows
Argon uses
-used and light bulbs to protect the filament from reacting with oxygen and nitrogen in the air
-used in neon lights
Krypton and xenon uses
used in lasers
Physical properties of a transition metal:
- Malleable, ductile, conducts heat and electricity well
- Far less reactive than main block metals
- Can form more than one type of ion eg. Cu 2+ & Cu 3+
- forms coloured compounds
Mendeleev’s periodic table
Arranged the 50 or so known elements at the time in order of mass so that they formed columns of elements that had similar properties
He swapped some elements around so that they were not in order of mass but their properties fitted with the other elements in the column
He used his table to predict the existence and properties of yet undiscovered elements (eg germanium)
When these elements were discovered, scientists became convinced that Mendeleev’s table was a very important discovery.
The Modern Periodic Table
Is different to Mendeleev’s as atomic number (number of protons in an atom) is used to order the elements not atomic mass. This gives a perfect pattern and no elements have to be ‘swapped’ around.
It contains 118 elements
