2334154
Descripción
Fichas por milicevic.marija, actualizado hace más de 1 año
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Creado por milicevic.marija
hace más de 9 años
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| Pregunta | Respuesta |
| What are the positions of protons, neutrons and electrons in the atom? | Protons and neutrons found in nucleus. Electrons on electron orbit. |
| What is the relative mass and charge of proton, neutron and electron? | Proton - 1 relative mass, +1 Neutron - 1 relative mass, 0 Electron - 0.0005 relative mass, -1 |
| What is mass number? | Number of protons plus the number of neutrons in an atom |
| What is an atomic number? | Number of protons in the nucleus |
| What is an isotope? | Same element, with different mass number |
| In the periodic table which number is by the top of the element and which is at the bottom? | Top - atomic number Bottom - mass number |
| How can you tell the number of protons or electrons? | no. of protons = no. of electrons = atomic number |
| How can you tell the number of neutrons? | no. of neutrons = mass no. - number of protons |
| What is cation? | a positive ion |
| What is an anion? | A negative ion |
| Compare the properties of the isotopes of an element | Isotopes show same chemical properties as change in no. of neutrons have no effect. Physical properties such as boiling and melting points change. Heavier isotopes move more slowly at a given temp, and therefore these differences can be used to separate isotopes. |
| What can radioisotopes treat? | Cancer |
| Describe isotopes | Radioisotopes have the same chemical properties as any other atom of that element, so they play the same role in the body. They can be monitored by detecting radiation levels making them tracers. |
| Give an example of a radioisotope tracer | Iodine -131 emits beta and gamma rays, investigating the thyroid gland |
| What are the dangers of radioisotopes? | Living organisms can be seriously affected if they are exposed to uncontrolled radiation may result in excessive use and their release into the environment |
| Draw a mass spectrometer | |
| What does a mass spectrometer measure? | the mass of different isotopes and their relative abundance |
| What are the 5 basic operations? | Vaporisation Ionisation Acceleration Deflection Detection |
| What is vaporisation? | Vaporised sample is injected into instrument. Allows individual atoms of an element to be analysed |
| What is ionisation? | Atoms are hit with high energy electrons which knocks off an electron creating a positive ion X+e->X+2e |
| What is Acceleration? | Positive ions are attracted to negatively charged plates. They are accelerated by an electron field and pass through a hole in the plate. |
| What is deflection? | Accelerated positive ions are deflected by a magnetic field. Amount of deflection is proportional to charge/mass ratio. |
| What is the ratio of deflection? | Smaller mass = more deflection Higher charge = more deflection |
| What is detection? | Positive ions of a particular charge/mass ratio are detected and a signal is sent to a recorder. Strength of the signal reflects the number of ions with that particular charge/mass ratio detected |
| How can a mass spectrometer be used to determine the relative atomic mass using the carbon-12 scale? | Mass spectrometer measures mass of individual atoms. As it is in the range of x10^-24 and x10^-22 a relative standard is needed. 12C is the chosen standard. It is the most abundant isotope of carbon. The results of mass spectrometers are presented in a mass spectrum |
| Go over the page of notes | one with 2.2.3 |
| Describe the electromagnetic spectrum | All electromagnetic waves travel at the same speeds (c) but can be distinguished by their different wavelengths. Different colours of visible light have different wavelengths. Red light has a longer wavelength than blue light. When sunlight passes through a prism, it produces a continuous spectrum |
| What is frequency? | number of waves that pass through a particular point c=f*wavelength |
| What is white light? | A mixture of light waves of differing wavelengths and colour |
| Distinguish between continuous spectrum and line spectrumq | When sunlight passes through a prism, it produces a continuous spectrum. When white light is passed through hydrogen gas, an absorption spectrum is produced. |
| Explain how the lines in the emission spectrum of hydrogen are related to electron energy levels | Hydrogen atoms give out energy when an electron falls from a higher energy level to a lower one. Hydrogen produces visible light when the electron falls to the second energy level (n=2). Transitions to first energy levels correspond to a higher energy change and are in the ultraviolet region of the spectrum. Patterns of the lines give a picture of energy levels in the atom. Lines converge at higher energies because the energy levels inside the atoms are closer together. When an electron is at the highest energy level (n=infinity) it is no longer in the atom, and the atom has ionised. Ionisation energy is the energy needed to remove an electron from the ground state of each atom in a mole of gaseous atoms. |
| What are the different types of spectra? | continuous emission continuous absorption line emission line absorption |
| What is Planck's equation? | E=hn E = energy of the emission h = Plancks constant (6.02 x 10-34) n = frequency of the radiation (the frequency is related to the wavelength by c = ln, c is the speed of light and l is the wavelength) |
| How is evidence for electron configuration formed? | Energy is given to particles and response is detected. Hypotheses are tested by all means available. Accurate hypothesis becomes theory and eventually 'truth' |
| What and how is used to determine the structure of an atom? | Spectra: An electron absorbs heat or electrical energy and is promoted to a higher level The electron returns to the original level and emits the difference as a specific electromagnetic radiation. The wavelength seen is related to the energy of the emission by Plancks equation |
| What is the first ionisation energy? | Minimum energy required to remove an electron from a gaseous atom |
| Explain how evidence from first ionization energies across periods accounts for the existence of main energy levels and sub-levels in atoms | As nuclear charge increase, electrons require more energy to remove (in the same period). |
| Why does sulphur not fit the pattern? | because removing the 3p electron leaves a stable configuration so this requires less energy than predicted OR you can say that the electron pair in the 3p repel , making the energy required to remove it lower than the pattern would suggest. |
| Explain how successive ionisation energy data is related to the electron configuration of an atom | Successive ionization energies show the energy levels (rings) in an atom. Low IE (easy to remove electron) = electrons are far from the pull of the nuclei, neutral atom, lots of shielding (between the electron in question and the nuclei are many electrons "in the way) High IE (hard to remove electron) = electron close to nucleus, positive ion, no shielding. |
| State the relative energies of s,p,d, f orbitals in an energy level | S is lowest energy level F is highest Example:4s is the lowest energy (closest to the nucleus), then 4p, then 4d and finally the 4f orbitals have the highest energy levels (furthest from the nucleus). |
| State the maximum number of orbitals in a given energy level | n = energy level Number of orbitals = n squared look at energy level, then number of electrons, divide number of elecrons by two because you can only fit two electrons in an orbital |
| Draw the 1 s orbital | |
| Draw the 2 s orbital | |
| Draw the 3 s orbital | |
| draw the px orbital | |
| draw the py orbital | |
| Draw the pz orbital | |
| why is a very low pressure is maintained inside the mass spectrometer? | To prevent collisions or unintentional deflection |
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