C1- Atomic structure ⚛️ Flashcards
What does the periodic table show you?
All the elements.
What’s an element?
Hint: substance
- an element, is a substance made of one type of atom [because each atom of an element, has the same number of protons]
Define the term ‘compound’
Hint: fixed proportion
- A compound is two or more elements that are chemically combined, in a fixed proportion.
What’s a mixture?
- A mixture is different element or compounds, that aren’t chemically combined (together).
What’s a molecule?
- A molecule has any elements chemically joined (they can be the same element).
What’s an atom
Hint: smallest part
- An atom is the smallest part of an element, that can exist.
When interpreting a chemical formula, how can we work out how many elements + atoms we have? [2]
- Count the big numbers for elements . E.g= MgS, has two elements: magnesium + sulfur.
- If there’s a number next to them, thats how many atoms there are. In MgS, there would be one atom of magnesium + one atom of sulfur.
Can you name the four physical separation techniques? [4]
- filtration
- crystallisation
- distillation
- chromatography
How can we separate mixtures?
- We can use physical separation techniques, to separate mixtures. For example- filtration
When is filtration used?
- Filtration is used to separate an insoluble solid from a liquid.
What’s the process of filtration? [3]
- use a filter funnel + filter paper
- pour the mixture into filter paper + the liquid passes through tiny pores in the filter paper
- so the solid can’t pass through the filter paper, so it’s trapped.
Describe a method for crystallisation? [5]
Hint: evaportaing dish, evaporate, crystals form, filter
- pour solution into an evaporating dish + gently heat the solution.
- some of the solvent will evaporate + the solution will become more concentrated.
- When the solvent evaporates/when crystals start to form, remove the dish from the heat + leave solution to cool.
- salt should start to form crystals, as it becomes insoluble in the (cold + highly concentrated solution).
- Then filter the crystals from the solution, leaving them in a warm place to dry.
What is simple distillation?
Hint: liquid from a solid
- Simple distillation is used, to seperate a liquid from a solid, if we want to keep the liquid.
What is fractional distillation?
- Fractional distillation allows us to separate two different liquids. [that have different boiling points]
Explain how simple distillation is set up [3]
Hint: a flask, condenser, sink
- First place the solution with the liquid and dissolved solid in a flask, with is connected to a continuous glass tube.
- the glass tube is surrounded by a condenser, and cold water from the tap, continuously runs through the condenser- keeping the internal glass tube cold.
- After running the condenser, the water then goes down the sink.
Describe a method of how you would carry out simple distillation. [3]
Hint: heat solution, condenses, collects
- the solution is first heated + the part of the solution with the lowest boiling point, evaporates first.
- the vapour is then cooled, condenses [back into a liquid] and is collected.
- ; the rest of the solution is left behind in the flask.
- [ ; simple distillation is carried out: by evaporating the liquid (by heating), then condensing the vapour (by cooling)]
Describe a method of how you would carry out fractional distillation? [6]
Hint: flask + fractionating column, temperature, boiling point, top, raise temp
- put the mixture in a flask + add a fractionating column on the top. Then begin to gently heat.
- since the different liquids will have different boiling points, they will evaporate at different temperatures.
- the liquid with the lowest boiling point evaporates first + when the temperature on the thermometer reaches the boiling point of the liquid, it then reaches the top of the column.
- ; liquids that have higher boiling points might begin to evaporate- but they will condense and run back towards the flask [as the fractionating column is cooler, towards the top]
- Finally, when first liquid is collected, raise the temperature again [until the next liquid/chemical reaches the top]
Why did new evidence from Rutherford’s scattering experiment, lead to a change in the atomic model? [2]
Hint: explained
- The experimental results of the gold foil experiment could not be explained using the plum pudding model.
- so the plum pudding model was disapproved and a, new model called the nuclear model (Bohr) was made to match the results.
What’s the difference between the nuclear model of an atom + the plum pudding model? [5]
Hint: empty space, distance, distributed throughout, ball of.., mass…
Nuclear model of atom:
- The atom is mostly empty space + negative electrons orbit the nucleus at a distance
- almost all the mass of an atom was actually concentrated in the positively charged nuclues.
Plum pudding model:
- the atom is a positively charged ‘ball’ of positive charge
- mass of atom is evenly distributed.
- negative electrons are distributed through the atom.
What are the observations in Rutherford’s experiment that lead to conclusions? [1]
Hint: deflected, repel
- Some of the alpha particles were deflected= so the centre must have a positive charge + that repelled alpha particles.
What are the observations in Rutherford’s experiment that lead to conclusions? [1]
Hint: through 🏆foil, model wrong
- most of the alpha particles went straight through the gold foil = so therefore atoms are mainly empty space. [meaning the plum pudding model had to be wrong]
What are the observations in Rutherford’s experiment that lead to conclusions? [1]
Hint: straight back 🔙 ,mass
- Some alpha particles bounced straight back= so the mass of an atom, must be concentrated in the centre/the nucleus
- [nuclear model replaced plum pudding model]
What did the ancient greeks/Democritus think about atoms?
Hint: individable
- the ancient greeks thought, that everything is made of atoms + atoms are tiny spheres, which can’t be divided.
What are the steps for the alpha scattering expirement? [2]
Hint: hammered, fired
- Rutherford took a piece of gold foil [gold can be hammered into a few atoms thick]
- and he and his scientists, fired alpha particles from a helium nuclei.
How were protons and neutrons discovered? [2]
Hint: positive charge–> positive particles
- Scientists found the positive charge of a nucleus, is due to positive particles [called protons]
- and (James) Chadwick discovered that the nucleus also contains neutrons, which have a neutral charge
