C1 - Atomic structure Flashcards
What defines a chemical reaction?
-one or more new products are formed from the reactants
-usually has a detectable energy change
How do you write an ionic equation?
-write out full balanced equation
-identify ionic substances and write the ions out, leaving the non-ionic substances as they are
-eliminate spectator ions (ions that appear on both sides of the equation that remain unchanged)
What does a half equation represent?
represents what happens to one of the reactants in a certain reaction in terms of gaining/losing electrons (reduction/oxidation)
Use OiL RiG - oxidation is loss, reduction is gain
How do you write a half equation?
-take ionic equation and remove all elements apart from the one you need
-one side will have an ion, the other will have an element
-add electrons to either side to balance the charges
How can a solution be separated, and what do these processes extract from it?
-filtration (insoluble solids in liquid)
-crystallisation (soluble solids in solution)
-distillation (solvent from a solution)
-fractional distillation (liquids with different boiling points)
-chromatography (identifying substances from a mixture in solution)
Why are the products of this reaction difficult to separate if magnesium is used to reduced silicon dioxide?
both of the products are solids, which are very hard to separate
It has nothing to do with its reactivity - separation is a physical process.
What was an atom thought to be before the discovery of the electron? Who thought of this?
-John Dalton
-tiny indivisible spheres
What did JJ Thompson discover? What model did he develop subsequently?
-the electron
-plum pudding model, suggesting a positively charged ball with electrons embedded in it
What did Rutherford and Marsden do to change the latest model of the atom? What was the new model named?
-alpha particle scattering experiment
-made the nuclear model
Description of this model is found in another flashcard
Who adapted the nuclear model and how did it change?
-Niels Bohr
-electrons orbit the nucleus at specific distances called shells/energy levels
-changed to the Bohr model
After Niels Bohr adapted the nuclear model, how was it changed in later experiments?
the positive charge in the nucleus was found to be subdivisible into individual particles with an equal amount of charge distributed between them (protons)
Who discovered the neutron?
James Chadwick
Chadwick’s experimental work on the atom led to a better understanding of isotopes. Explain how:
-Chadwick provided the evidence to show the existence of neutrons
-this was necessary because isotopes are atoms of the same element but with different numbers of neutrons
How did the alpha particle scattering experiment provide new insight on the structure of the atom?
they expected all of them to go straight through
-some α bounced back, showing it has a dense nucleus
-the nucleus is positively charged as some α were deflected
-the atom is mostly empty space, as most passed through unaffected
-the electrons must exist elsewhere in the atom, as the nucleus is positive but the overall charge is neutral
Summarise the development of the model of the atom:
-electrons discovered, plum pudding model
-nuclear model with α scattering experiment
-Bohr model
-protons discovered
-neutron discovered
Which of these diagrams shows the model of the atom after the alpha scattering experiment and why?
-C
-they knew that there was a nucleus (and electrons somewhere around it) but hadn’t discovered that it was subdivisible into protons yet
What is relative atomic mass? How is it calculated?
an average value of the mass of an element that accounts for the abundance of its different isotopes
Make sure to use a percentage value for the abundance - if not, you can remove the % sign but divide the result by 100
