Atomic Structure and The Periodic Table Flashcards
What subatomic particles are found in the nucleus of an atom?
protons and neutrons
What is the relative mass and relative charge of a proton?
Relative mass = 1
Relative charge = +1
What is the relative mass and relative charge of a neutron?
Relative mass = 1
Relative charge = 0
What is the relative mass and relative charge of an electron?
Relative mass = very small
Relative charge = -1
What is an isotope?
Different forms of the same element, which have the same number of protons but a different number of neutrons.
What is relative atomic mass?
An average mass taking into account the different masses and abundances of all the isotopes that make up an element.
What is the formula for relative atomic mass?
Ar = sum of (isotope abundance x isotope mass number) / sum of abundances of all the isotopes
Give the method on how to do paper chromatography.
- Draw a straight line near the bottom of the paper using a pencil.
- Add a spot of ink to the line and place in a beaker of solvent, making sure that the solvent isn’t touching the ink.
- The solvent seeps up the paper carrying the ink with it. When the solvent is near the top, take the paper out and leave to dry.
- Measure the solvent front (the point the solvent has reached) with a ruler.
- The end result is a pattern of spots called a chromatogram.
Give the method for making salts using crystallisation.
- Use a measuring cylinder to add 40 ml of sulfuric acid in a beaker.
- Gently heat the beaker in a water bath for a couple of minutes.
- Carefully add a spatula of copper oxide powder to the beaker and stir the solution with a glass rod, add in excess until it no longer disappears.
- Filter the mixture using a funnel and filter paper to remove the excess copper oxide.
- Then pour the filtrate (the copper sulfate solution) into an evaporating basin
- place the evaporating basin above a bunsen burner on a tripod and gauze, and heat the copper sulfate solution to evaporate off half of the water.
- Pour the solution into a watch glass and leave on a windowsill or dry area to allow all of the water to evaporate or pat dry.
Explain how filtration and crystallisation can be used to separate rock salt.
- Grind the mixture to make sure the salt crystals are small so will dissolve easily.
- Put the mixture in water and stir.
- Using filter paper and a funnel, filter the mixture into a beaker.
- Evaporate the water from the salt so that it forms dry crystals.
Explain simple distillation.
- Used for separating out a liquid from a solution.
- The solution is heated. The part of the solution that has the lowest boiling point evaporates first.
- The vapour then travels up the flask and is condensed in a condenser back into a liquid.
- The liquid is collected in a beaker and the rest of the solution remains in the flask.
Explain fractional distillation.
Used to separate a mixture of liquids.
1. Put the mixture in a flask with a fractionating column on top. Heat over a bunsen burner.
2. The different liquids have different boiling points so will evaporate at different temperatures.
3. The liquid with the lowest boiling point evaporates first. The vapour travels up the fractionating column and then condenses into a liquid.
4. Liquids with higher boiling points might also start to evaporate but the column is cooler towards the top so it will only get part way before condensing and running back down the flask.
5. When the liquid has been collected, raise the temperature to collect the next liquid.
How has the theory of atomic structure changed over time?
19th Century
- John Dalton described atoms as solid spheres and said different spheres were made of different elements
1897
- JJ Thompson created the plum pudding model consisting of a positively charged mass containing smaller negatively charged electrons
1909
Ernest Rutherford conducted an experiment that concluded that when alpha particles were fired at thin sheets of gold, most particles passed through empty space but a few were deflected by the nucleus.
How did Rutherford show that the plum pudding model was wrong?
Alpha particle scattering experiments
- fired charged alpha particles at a thin sheet of gold
- they were expecting particles to pass straight through or be slightly deflected at most however more than expected were deflected or deflected backwards.
- This meant that there was a positively charged nucleus within an atom consisting mostly of empty space
What is the plum pudding model?
A positively charged mass containing smaller negatively charged particles called electrons.
What does Bohr’s nuclear model show?
Electrons are contained in shells and orbit the nucleus. Each shell is a fixed distance from the nucleus.
How were elements arranged in the early 1800s?
By atomic mass.
What did Dmitri Mendeleev arrange the elements?
In order of atomic mass but he left gaps to make sure that elements with similar properties stayed in the same group. Some of these gaps indicated the existence of undiscovered elements.
True or false : Most elements in the periodic table are metals.
True
What are metals?
Elements which can form positive ions when they react.
Where are non-metals located in the periodic table?
The top far right.
What does the electronic structure of atoms affect?
How they will react.
