C4.1 Flashcards
Dobereiner 1829
Triplets or triads of elements seemed to exist,with similar properties
Newlands-1866
Proposes patterns between elements
He used an ‘octave’ pattern,which showed every eighth element to be similar
Mendeleev 1871
Published his version of the periodic table
This made predictions about the properties and mass of yet discovered elements. He left gaps in his table to be filled when they were found
Mendeleev’s rules
1) out elements in order of their relative atomic mass
2) put elements that are chemically similar in the same group (column)
2 elements Mendeleev predicted to exist
Gallium - 1875
Germanium- 1886
Chlorine(g) - room temp
Pale green
Bromine(l) - room temp
Dark brown
Iodine (s) - room temp
Dark grey solid
Bromine when a gas
Dark brown
Iodine when heated
Purple has
Alkali metals react with water to form what?
Hydrogen and an alkaline solution of a hydroxide with the formula MOH
Alkali metals react vigorously with what? To form what?
With chlorine to form colourless,crystalline salts with the formula MCl
Atoms of each element have different what?
Proton numbers
What does arranging the elements in order of their proton number give?
Repeating patterns in the properties of elements
As you go down the group the melting and boiling point get….
The density is …..
(Group 1)
Lower as you go down the group
Density = low
Lithium when reacts with water
Fizzes slowly,water turns purple
Sodium when reacts with water
Fizzes faster,water turns purple
Potassium when reacts with water
Fizzes a lot,water turns purple
As you go down the group… reactivity of alkali metals?
Become more reactive
What are alkali metals stored in?
Oil
Handling alkalis
Forceps not hands (sweat-scar-rage)
Kept away from large amounts of water
Goggles
Chlorine (g) at room temp
Pale green
Bromine (l) at room temp
Dark brown
Bromine (l) when a gas
Dark brown
Iodine (s) at room temp
Dark grey solid
Iodine (s) when a gas
Purple
Halogens consist of what?
Diatomic molecules
Halogens- melt and boiling point
High
As you descend the group,the group 7 elements become…(reactive)
Less reactive
Halogens-reaction with potassium chloride solution
No reaction
Chlorine water- reaction with potassium bromide solution
Yellow/orange colour of bromide appears
Bromine reaction with potassium bromide
No reaction
Iodine reaction with potassium bromide
No reaction
Chlorine water reaction with potassium iodide solution
Brown colour of iodine appears
Bromine water reaction with potassium iodide solution
Colour darkens from yellow/orange to brown
Iodine solution reaction with potassium iodine solution
No reaction
Fine cupboard-storing halogens
Any fumes released into air are sucked up into this and then are filtered to remove harmful chemicals
Let out= air
Keeps scientists safe
