C1-atomic Structure & The Periodic Table Flashcards
What is an isotope?
Different forms of the same element, which have the same number of protons but a different number on NEUTRONS.
When elements react, what do they form?
Compounds (substances made up of 2 or more elements chemically bonded)
What are mixtures?
2 or more elements and compounds mixed together but not chemically combined.
What is a method used to separate mixtures?
Chromatography (can be used to separate different dyes and inks)
How do you carry out chromatography?
-draw line in pencil near the bottom of filter paper
-add spot of ink on line
-place sheet in beaker of water
-make sure the ink isn’t touching the water
-place lid on beaker to avoid solvent evaporating
-watch the water carry the different inks at different rates.
If the dye is insoluble, it won’t move.
-take out paper once finished and dry.
-the end result is a pattern of spots called chromatogram.
What is the process used to separate insoluble solids from a liquid and how do you do this?
FILTRATION
- put folded filter paper into a cone shape
- pour in the mixture
- the liquid will seep through, and the solid will be left in the filter paper.
What are the processes used to separate soluble solids from a solution?
EVAPORATION
- pour solution in evaporation dish
- slowly heat solution. Solvent will evaporate and you will be left with hard crystals (your soluble solid)
CRYSTALLISATION
- pour solution in evaporating dish and gently heat.
- solvent will evaporate and solution will get more concentrated.
- once solvent begins to evaporate or when crystals begin to form, remove dish and allow to cool
- salt will form crystals
- filter the crystals and leave them to dry
What can be used to separate rock salt?
FILTRATION AND CRYSTALLISATION
- grind mixture
- put mixture in water and stir. Salt will dissolve but sand won’t.
- filter mixture
- evaporate water from salt so that it forms dry crystals.
What is simple distillation used to do? And how is this done?
To separate out solutions of different boiling points
-solution is heated
-solution with lowest boiling point evaporates first
-vapour is cooled and condenses and is collected.
Rest of the solution is left behind.
What is fractional distillation used to do? And how is this done?
Separate mixtures of liquids.
- put liquids in flask and add fractional column on top
- heat the liquid
- different liquids will have different boiling points and therefor will evaporate at different paces
- when the first liquid has evaporated and condensed and has been collected, you raise the temp until the next one evaporates.
Who proved the plum pudding model to be wrong, and what was it replaced with?
- Rutherford proved it was wrong in 1909
- He came up with the nuclear model.
- He proved the plum pudding model to be wrong by shooting positively charged alpha particles at an extremely thin piece of gold. From the plum pudding model, they expected the alpha particles to go right through it, however some deflected.
What did Neils Bohr’s nuclear model explain?
That all electrons were contained in shells.
How were elements classified in the early 1800’s?
By relative atomic mass
Describe 2 changes that Mendeleev made to the early periodic table?
He left gaps in order to keep elements with similar properties in same group and he switch the order of elements based on their properties even at their atomic masses were no longer in order.
What are some properties of metals and non-metals
METALS •strong •malleable •good conductors •high boiling & melting points NON-METALS •bad conductors •brittle & dull •low densities
