A-Level Edexcel Chemistry Examination Questions and Answers

How to test for C=C decolourises bromine water Atomic Number number of protons in the nucleus of an atom of that element. Mass Number the sum of protons and neutrons in a nuclues of an atom Isotopes atoms of the same elementwith the same numberof protons but different nuber of neutrons Relative Atomic Mass the average mass of an atom of an element compared to a twelfth of the mass of an atom of carbon-12. Relative Isotopic Mass The mass of an atom of an isotope compared to one-twelfth of the mass of an atom of carbon-12 Quantum Shell the energy level of an electron. Orbital a region around the nucleus that can hold up to two electrons with opposite spins. What shape is the S orbital spherical What shape is the P orbital dumbell First Ionisation Energy the measure of energy is needed to completely remove one mole of electron from one mole of gaseous atom Second Ionisation Energy is a measure of energy needed to remove one-mole of electron from one mole of gaseous ion Periodicity A repeating trend in the properties of the elements across the periodic table Why are copper and chromium important to do with filling up their subshells? because they have a half-filled subshell. This gives added stability so minimises electron repulsion