Ch3.1 The Periodic Table Flashcards
How many elements were there thought to be by the Ancient Greeks?
4: earth, fire, water and air
When and why was John Dalton relevant?
- first to give chemical symbols to elements in the early 19th century
When and why was Johannes Dobereiner relevant?
- he discovered mathematical patterns in the elements (triads)
- first to attempt arranging elements into groups
- 1829
When and why was John Newlands relevant?
- law of octaves: first recognition of periods in elements
- if elements are in repeating rows of 7, their properties repeat
- 1864
When and why was Dmitri Mendeleev relevant?
- arranged known elements in horizontal rows (periods) and vertical columns (groups) according to atomic weight
- left gaps for undiscovered elements and predicted properties of them with accuracy
- 1869
What happened between Mendeleev and Baron de Chancourtois?
- BdC sent a manuscript to M 1 year before M’s discovery of the periodic table
- contained writing and drawing of a periodic table
- M sent to publishers without the drawing then 1 year later ‘came up’ with the periodic table
Describe the appearance of fluorine
A pale yellow gas
Describe the appearance of chlorine
Green gas
Describe the appearance of bromine
Brown solid
Describe the appearance of iodine
Grey solid
Describe the appearance of astatine
Black solid
How do the halogens achieve stability?
They exist diatomically
Why do the halogens’ boiling points increase as you move down the group?
- atoms get bigger (more shells)
- more electrons in cloud
- stronger London forces
- more energy needed to overcome
State properties of halogens
- very reactive
- non-metals
- dense, coloured, poisonous gases
- react with s-block metals to form white salts
- 7 e- in outer shell
Describe the uses of fluorine
Used to make PTFE in non-stick frying pans and fluoride is used to prevent tooth decay
Describe the uses of chlorine
Kills bacteria in pools and drinking water, makes bleach and plastics
Describe the uses of bromine
Used in photographic film
Describe the uses of iodine
Antiseptic, essential part of diet for thyroid
What are the trends as you move down the group of halogens?
- less reactive
- darker in colour
- less electronegative
- less oxidising
- higher melting and boiling points
Which of the halogens doesn’t exist as a liquid?
Iodine, it goes through sublimation (solid straight to gas)
List the reactivity series and the way to remember it
Potassium
Sodium
Calcium
Magnesium
Aluminium
Zinc
Iron
Tin
Lead
Copper
Silver
Gold
Passive
Smoking
Can
Make
All
Zombies
In
To
Lazy
Crazy
Sex
Gods
What would the products be in a displacement reaction between chlorine and potassium iodide?
Potassium chloride and iodine
What chemical is used to distinguish between iodine and bromine
Cyclohexane
How are halide ions identified?
Using aqueous silver ions:
add nitric acid and silver nitrate which forms acidified silver nitrate
When aqueous silver ions are added to halide ions, what colour to they go depending on which halogen they derive from?
- chlorine = white
- bromine = cream
- iodine = yellow
After adding aqueous silver ions, if the colours are hard to distinguish between, how can this be solved?
- add ammonia
-dilute ammonia turns the white of Cl colourless
- concentrated turns the cream of Br colourless
- the yellow of I cannot be turned colourless
What is brine?
Very concentrated NaCl solution (very salty water)
How is bleach manufactured?
Chlorine is reacted with sodium hydroxide to produce sodium chloride, sodium chlorite (bleach) and water
What happens to chlorine during the reaction of forming bleach?
It is both oxidised and reduced meaning it is a disproportionation reaction
How is group 2 on the periodic table similar to group 1?
- metals from both groups make alkaline solutions and hydrogen gas when added to water
- both groups get more reactive as you move down
Where are alkaline earth metals found?
In large quantities in rocks
What rock is magnesium found in?
Dolomite
What rock is calcium found in?
Limestone
What rock is strontium found in?
Strontianite
