That whole fucking chem GCSE in a nutshell 🙂 Flashcards
What did newlands do for periodic table
- arranged elements in order of atomic mass
- left no spaces
Why was Mendeleev periodic table BETTER THAN newlands
- left spaces
- predicted properties
- atomic mass
Reactivity increases as you go down GROUP 1 because….
- elements are bigger ( more shells of electrons)
- outer shell electron further from nucleus- attraction decreases
- electron more easily lost
- MORE shielded
Group 1 in water…
- fizz, release hydrogen gas
- move around, float
- eventually sink
- make water purple when universal indicator added to it, meaning it alkali
Metal+ COLD water———>
Metal hydroxide+ hydrogen
Metal+ steam———->
Metal oxide+ hydrogen
Why do group 7 elements become less reactive as you go down group
- elements are larger
- harder to gain electron
- outer shell electron is further from nucleus and more shielded
Properties of halogens
- LOW boiling points
- poor conductors
Properties of transition metals
- GOOD conductors of heat and electricity
- hard
- strong
- high density
- high MELTING points
Describe the properties of transition metal compounds
- coloured
- catalysts
- multiple ions
When does ionic bonding occur
Between metals and non metals
When does covalent bonding occur
Between non metals only
Covalent bonding is…….
A shared pair of electrons
Ionic bonding is…..
Strong forces of attraction between oppositely charged ions
Why do ionic structures have such high MELTING points?
- strong forces of attraction between oppositely charged ions
- require lots of energy to break
Why are ionic structures brittle?
- when force is applied ions with the same charge end up next to each other
- like charges repel
- structure falls apart
Structure of metals….
- positive ions
- surrounded by a sea of delocalised electrons
Alloy?
Mixture of two or more metals
Why are alloys harder than individual metals?
- ions of different sizes
- more difficult for layers to slide over each other
Why does DIAMOND have such a high MELTING point
- giant covalent structure
- EACH carbon atom is bonded to four others
- many strong covalent bonds
- require lots of energy to break
GRAPHITE IS THE SAME JUST BONDED TO THREE OTHERS NOT FOUR
Why does graphite conduct electricity
- EACH carbon atom is only bonded to three others
- 4th electron free to move
Why is graphite used as a lubricant
- Carbon atoms arranged in layers
- layers are held together by weak intermolecular forces
- does not require a lot of energy to break
- layers slide off each other
Define polymer
A large molecule formed of many small monomers which JOIN together
Define Thermosetting polymer
Can’t be heated and then RE shaped
Define thermosoftening polymer
Can be heated and RE shaped
CHAINS ARE HELD TOGETHER BY WEAK INTERMOLECULAR FORCES WHICH ARE EASY TO RE SHAPE
SOME examples of nanoscience in industry
- glass coated in nanoparticles. Sunshine triggers reaction which breaks down dirt
- sunscreen contains nano particles which are better blockers of UV rays
- nanoparticles in face creams are absorbed deeper into the skin
Method of titration
100% copied this off bitesize, its got it all there friends
Use the pipette and pipette filler to add 25 cm3 of alkali to a clean conical flask.
Add a few drops of indicator and put the conical flask on a white tile (so you can see the colour of the indicator more easily).
Fill the burette with acid and note the starting volume.
Slowly add the acid from the burette to the alkali in the conical flask, swirling to mix.
Stop adding the acid when the end-point is reached (the appropriate colour change in the indicator happens). Note the final volume reading.
Repeat steps 1 to 5 until you get consistent readings
The same method works for adding an alkali to an acid - just swap around the liquids that go into the conical flask and burette.
Less than 100% yield in titration (or I guess other reactions idrk) because……..
- SOME product is lost
- reversible reaction
- reactant form unexpected products
Reactivity series
POTASSIUM SODIUM LITHIUM CALCIUM MAGNESIUM ALUMINIUM CARBON ZINC IRON HYDROGEN COPPER SILVER GOLD
TEST for hydrogen
Lighted splint
Squeaky pop
Hydrochloric acid+ sodium hydroxide—–>
Acid+ base= Salt+ WATER
Sodium chloride+ water
GET THE NAME OF THE SALT, IN THIS CASE SODIUM AND THEN PUT THE END OF THE ACID NEXT TO THE SALT… HYDROCHLORIC= CHLORIDE SO SODIUM CHLORIDE
Metal+ acid= Salt+ hydrogen
Nitric acid+ magnesium——->
Magnesium nitrate + hydrogen
Acid+ metal oxide——->
Salt+ WATER
Acid+metal carbonate——->
Salt+ WATER + carbon dioxide
PANIC
Positive anode
Negative is cathode
