Atomic Structure and the Periodic Table Flashcards
On the conetnt (21 cards)
Elements
What is the definition of an isotope?
They are differenent forms of the same element, which have the same number of protons but a different number of neutrons. [1].
Isotopes
What is the equation of calculating relative formula mass using an isotopes?[1]
Sum of (isotope abundance x isotope mass number)/ sum of abundance of all isotopes
Mixtures and Chromatography
State and explain the necessary steps need to be taken for the investigation to seperate different dyes in an ink. [6]
Draw a line near the bottom of a sheet of filter paper.
Use pencil as pencil marks are insoluable
Add a spot of the ink to the line and place the sheet in a beaker of solvent.
Make sure the ink isn’t touching the solvent as you don’t want the ink to dissolve.
Place a lid on top of the container to stop the solvent evapourating.
The solvent seeps up the paper, carrying the ink with it.
Each different dye in the ink will move up the paper at a different rate so the dyes will seperate out. Each dye will form a spot in a different place.
If any of the dyes in the ink are insoluable in the solvent used, they will stay on the baseline.
When the solvent has nearly reached the top of the paper, take the paper out of the beaker and leave it dry.
The end result is the pattern of spots called chromotogram.
More Seperation Techinques
State the necessary steps to seperate the soluable solids from solutions. [4]
Pour the solutions into an evapourating dish. [1]
Slowly heat the solution.
[1]
The solvent will evapourate and the solution will get more concentrated. Eventually crystals will start to form.[1]
Keep heating the evapourating dish until all you have left is dry crystals.[1]
More serperation techinques
State the necessary steps to seperate the soluable solids from solutions using crystalisation. [6]
Pour the solution into an evapourating dish and gently heat the solution.[1]
Some of the solevent will evapourate and the solution will get more concentrated. [1]
When some of the solvent has evapourated and starts to from crystals this is called the point of crystalisation. [1]
Remove the dish from the heat and leave the solution to cool[1]
The salt should start to form crystals as it becomes insoulable in the cold, highly concentrated solution. [1]
Filter the crystals out of the solution, and then leave them in a warm place to dry.[1]
Use a drying oven for this.[1]
How can filtration and crystalisation be used to seperate rock salt.[6]
Grind the mixture to make sure the crystals are small so will dissolve easily.[1]
Put the mixture in water and stir.[1]
The salt will dissolve but the sand won’t.[1]
Filter the mixture.
[1]
The grains of the sand won’t fit through the tiny holes in the filter paper so they collect on the paper instead.[1]
The salt passes through the filter paper as it is part of the solution.[1]
Evapourate the water from the salt so that it forms crystals.[1]
What is the definition of distillation?[1]
The seperation of liquids in a mixture.[1]
Distillation
State the necessary steps to seperate pure water and sea water. [5]
The solution is heated.[1]
The part of the solution has the lowest boiling point evapourated first which is the seawater. [1]
The vapour is then cooled and condenses[ turns back into liquid] and is collected. [1]
The rest of the solution is left behind the flask. [1]
The water evapourates and is condensed and collected.[1]
You will end up with salt left in the flask.[1]
The control variable is the volume of the liquids.
What is the definition of fractional distillation?[1]
The seperation of liquids with similar boiling points
Fractional distillation
State the necessary steps needed to be taken to use fractional distillation. [6]
You put your mixture in a flask and stick a fractionating column on top. [1]
Then you heat it.
The different liquids willl have a different boiling points so they will evapourate at different temeprature.[1]
The liquid with the lowest boiling point will evapourate first. [1]
When the temperature on the thermometer matches the boiling point of the liquid it will reach the top of the column.[1]
Liquids with a higher melting point might also start to evapourate
The column is coller towards the top so they will only get part of the way up before condensing and running back down towards the flask. [1]
When the first liquid has been collected you raise the tempertaure until the next one has reached the top.[1]
The history of the atom
Why was the plum pudding considered to be wrong?[1]
Because more particles were deflected more than expected and a small number were deflected backwards in the alpha particle experiment.
The History of the Atom
Describe the structure of an atom based on the nuclear model.[3]
There is a tiny, postively chraged nucleus at the centre where most of the mass is concentrated.
A cloud of the negative electrons surrounded he nucleus so most of the atom is empty space
The History of the Atom
Why was the nuclear model of atom by Rutherford not accepted by scientistists. [2]
The electrons are in a cloud around the nucleus of the atom would be attracted to the nucleus causing the atoms to collapse. [1]
The History of Atom
Describe Bohr nuclear model of atom[2]
The electrons orbit the nucleus in fixed shells[1] as each shell is a fixed distance from the nucleus.[1]
Why did Mendeleev put elements mainly in their atomic weight?[1]
So elements in that group have a similar properties..[1]
State two reasons as why did Mendeleev leave gaps in the periodic table?[2]
Some of these gaps indicated the existence of the undiscovered elements and allowed Mendeleev to predict what their properties might be. [1]
To make sure that elements with similar properties stayed in the same groups. [1]
Atom
“What is the relative mass of a proton and a neutron?”
1
1
Development of the Periodic Table
Why was Mendeleeve percieved to be wrong when placing elements in a strict order of atomic weight?[1]
Because of the discovery of isotopes that elements have different masses but have the same chemical properties to occupy the same position on the periodic table.
Metals and Non-metals
State 3 properties of a non-metal?[3]
They tend to be dull looking.[1]
They aren’t solid at room temperatures[1]
They don’t conduct electricity.[1]
Metals and Non-metals
State 3 properties of transition metals?[3]
They make a good catalysts. [1]
Tranisition metal ions s are often coloured [1]
They have more than one ion.[1]
