A level Chemistry Topic 1 Questions and Answers

A level Chemistry Topic 1 Questions and Answers Define an element Substance made of one type of atom with the same number of protons Define an isotope Atoms which have the same number of protons but different number of neutrons Define an ion Atom which has different number of protons and electrons, with a positive or negative charge Define an orbital Region within an atom that can an electron can be found, holding up to 2 electrons Define the term "Relative Atomic Mass" Weighted mean mass of an atom of an element compared to 1/12 the mass of an atom of Carbon-12 Define the term "Relative Isotopic Mass" Mass of an isotope of an element compared to 1/12 of the mass of an atom of Carbon-12 How does a mass spectrometer help differentiate between isotopes By deflecting positive ions and separating them due to their mass to charge ratio Why does the mass spectrometer of chlorine have two peaks at 35 and 37? Two differing isotopes What is the ratio of Chlorine 35 atoms to Chlorine 37 atoms in a mass spectrum 3 to 1 ratio Why does the mass spectrum of chlorine have peaks at 70m/z, 72m/z and 74m/z? Due to Chlorine being diatomic, and different combinations of isotopes combined for these peaks on a spectrum What is the ratio of the peaks at 70m/z, 72m/z and 74m/z in the mass spectrum of Chlorine? 9 to 6 to 1 Bromine has two isotopes, 79 and 81, of equal abundance. How would this appear on a spectrum? Two peaks of equal height/abundance Bromine has peaks at 158, 160 and 162. What is the ratio of these peaks 1:2:1. The peak for 160 would be double the other peaks What shape is an s orbital? Spherical What shape is a p orbital? Dumb-bell What is the maximum no of electrons in the 1st quantum energy level? 2 What is the maximum no of electrons in the 2nd quantum energy level? 8 What is the maximum no of electrons in the 3rd quantum energy level? 18 What is the maximum no of electrons in the 4th quantum energy level? 32 How many s orbitals per quantum energy level? 1 orbital How many p orbitals per quantum energy level? 3 orbitals How many d orbitals per quantum energy level? 5 orbitals How many f orbitals per quantum energy level? 7 orbitals How many electrons occupy the s orbitals? 2 electrons How many total electrons occupy the p sub-shell? 6 electrons How many total electrons occupy the d sub-shell? 10 electrons How many total electrons occupy the f sub-shell? 14 electrons State the sub-shell order up to and including the 4p sub-shell 1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁶ Why does the 3d orbital fill up after the 4s sub-shell? The 4s sub-shell is at a lower quantum energy level than the 3d sub-shell so fills first Draw a spin diagram for Oxygen Teacher to draw on board Draw a spin diagram for Nitrogen Teacher to draw on board Define the "First Ionisation Energy" The energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions Give an equation for the 2nd ionisation energy of Lithium Li(g) → Li⁺(g) + e⁻ Which three factors affect ionisation energy? Nuclear Charge, Electron Sub-Shell Distance and Electron Shielding How does ionisation energy change across a period? Increases across a period How does ionisation energy change down a group? Decreases down a group Where does evidence for differing energy levels in atoms come from? Emission Spectra When electrons are given energy, what happens to them? Excited, move to higher energy levels When electrons release this energy, what is emitted? Electromagnetic Radiation What is meant by the term s-block element? Element whose valence electron is within a s orbital What is meant by the term p-block element? Element whose valence electron is within a p orbital What is meant by the term f-block element? Element whose valence electron is within an f orbital What is meant by the term d-block element? Element whose valence electron is within a d orbital Explain why the chemical properties of Group 1 elements are similar Same number of valence electrons An element has the configuration 1s²2s²2p², which element is it and which block is it in? Carbon; p block Explain what is meant by the term periodicity Repeating pattern of properties across differing periods in the Periodic Table How does atomic radii vary across a Period? Radius decreases across a period How does boiling and melting point vary across a Period? Melting and Boiling Point generally increase then decrease across a period Why does atomic radii vary across a Period? Increased number of protons, so increased nuclear charge. Increased attraction between nucleus and furthest electrons Why does melting and boiling point vary across a Period? Changes in the type of bonding and type of structure as you move across a period. Why does Oxygen have a lower ionisation energy than Nitrogen? Oxygen has two paired electrons in one orbital, increases electron-electron repulsion, so less energy needed to remove one Explain why the first ionisation energy of helium is higher than hydrogen Helium has a greater nuclear charge than hydrogen, whilst electrons and a similar distance away from the nucleus in 1s orbital. Similar amount of electron shielding occurs Explain why the first ionisation energy of lithium is lower than helium Despite the higher nuclear charge due to more protons, lithium's valence electron is in the 2s orbital, a greater distance from nucleus and experiences more electron shielding