Atomic Structure/ Periodic Table Flashcards
(34 cards)
What is the radius of an atom
0.1 nanometres (1x10^-10)
What charge does the nucleus of an atom have
Positive
Where is the mass of an atom concentrated
In the nucleus
What charge are electrons
-1
What charge are protons
+1
What charge are neutrons
No charge
What is the relative mass of an electron
Very small
What does the atomic number tell you
How many protons there are
What does the mass number tell you
How many protons and neutrons
How do you find the number of neutrons in an atom
Mass number-atomic number
What is an isotope
An element with the same number of protons but a different number of neutrons
What is the equation for relative atomic mass
Sum of isotope abundance x isotope mass number
————————————————————————
Sum of abundances of all isotopes
What is the formula for ammonia
NH3
What is a compound
A substance formed from two or more elements chemically bonded
Chromatography practical (8 points)
- Draw a line near the bottom of a sheet of filter paper using a pencil (insoluble)
- Add a spot of ink to the line and place it in a beaker of solvent
- Make sure the ink isn’t touching the solvent so that it doesn’t dissolve
- The solvent will seep up the paper and carry the ink with it
- Each dye in the ink will move up the paper at different rates so they will separate out
- The insoluble dyes will remain on the baseline
- When the solvent almost reaches the top of the paper, take it out to dry
- The end result is a patters called a chromatogram
When is filtration used
When there is an insoluble solid in a solvent
What separation techniques do you use for a soluble solid
Evaporation
Crystallisation
Evaporation practical
- Pour a solution into an evaporating basin
- Slowly heat the solution. The solvent will evaporate and the solution will get more concentrated. Eventually crystals will start to form
- Keep heating the dish until all you have left are dry crystals
Crystallisation practical
- Pour the solution into an an evaporation dish and gently heat the solution. Some of the solvent will evaporate and the solution will get more concentrated
- Once you start to see crystals forming, remove the dish from the heat and leave the solution to cool
- The salt should start to form more crystals as it becomes insoluble in the cool, highly concentrated solution
- Filter the crystals out of the solution and leave them in a warm place to dry o
Why does the alpha particle scattering experiment disprove the plum pudding model
The plum pudding model give the impression that the alpha particles would pass straight through the atom, however Rutherford discovered some particles deflected backwards. Therefore he came up with the conclusion that there is a positively charged nucleus in the centre where most of the mass is concentrated, causing the particles to deflect.
How were elements classified in the 1800s
They were arranged by atomic weight
When did Mendeleev arrange his table of elements
1869
What did Mendeleev table of elements show and do (3 points)
He grouped elements together with similar properties and atomic weight
There were various gaps which indicated the existence of undiscovered elements
When they were found, they fit the pattern and helped confirm Mendeleev’s ideas
What does the group number tell you about elements
How many electrons are in the outer shell
