C1- Atomic Structure And The Periodic Table Flashcards
What do atoms contain
Protons, neutrons and electrons
Nucleus of an atom
Contains protons and neutrons has positive charge due to protons
Electrons
Move around nucleus in electrons shells, negatively charged, have virtually no mass
Protons
Positively charged, relative mass 1, euqals number of elctrons, number of protons is atomic number
Atoms charge
Nuetral, same number of protons as electrons
Mass number of element
Total number of protons and neutrons
Isotopes
Different forms of the same element, same number of protons but different number of neutrons
Relative atomic mass
Relative atomic mass= sum of (isotope abundance x isotope mass number) divided by sum of abudance of all the isotopes
Compounds
Formed when two or more elements are chemically combined
Mixtures
Unlike compounds easily separated, two or more elements mixed together but no chemically combined eg. Air
Properties of mixtures
A mixture of the properties of the separate parts- chemical properties of a substance aren’t affected by it being part of a mixture
Paper chromatography method
- Draw a line near bottom of filter paper using a pencil
- Add a spot of ink to line and place in beaker of solvent
- Make sure ink isn’t touching the solvent
- Place a lid on top of the contsiner to stop solvent evaporating
- Solvent seeps up paper carrying ink
- Each dye will move up paper at different rates
- If any dyes are insoluble they will stay on baseline
- When solvent has nearly reached top of papertake paper out and leave to dry
Filtration
Seperates insoluble solids from liquids
Two ways to separate soluble solids from solutions
Evaporation, crystallisation
Evaporation method
- Pour solution into evaporating dish
- Slowly heat solution to evaporate and the solution will get more concentrated snd crystals form
- Keep heating the evaporating dish until all you have left are dry crystals
Crystallisation
- Pour solution into an evaporating dish and gently heat solution
- Once crystals start to form remove dish from heat and leave to cool
- The salt should start to form crystals as it becomes insoluble in the cold, highly concentrated
- Filter crystals out of solution and leave them in a warm place to dry
Simple distillation
Seperates liquid from solution
Simple distillation method
- Part of solution that has the lowest boiling point evaporates first
- Vapour is then cooled, condenses and is collected
- The rest of solution is left in flask
Issue with simple distillation
Can only separate things with very different boiling points
Fractional distillation
Separtes mixture of liquids with similar boiling points
Fractional distillation method
- Put mixture in flask and put fractional column on top and heat it
- Different liquids will have different boiling point
- Liquid with lowest boiling point evaporates first. When the temperature matches the boiling point of thie liquid, it will reach the top of the column
- Liquids with higher boiling points may start to evaporate. But the column is cooler towards the top. So they will only get part of the way up before condensing and running back down towards the flask
- When the first liquid has been collected, you raise the tempersture until the next one reaches the top
John dalton
At start of 19th centruy Dalton described atoms as solid spheres and said that different spheres were made up the different elements
Jj thomson
1808 concluded from his experiments that atoms weren’t solid spheres. His measurements of charge and mass showed that an atom must contain even smaller negatively charged particles- electrons
Plum pudding model
Showed atom as a ball of positive charge with electrons stuck in it