up to fill up the orbitals that already have an electron in them. This leads to a total of 10 electrons in the five orbitals per period. As always, the spins of the electrons will be opposite when they do inhabit the same orbital. You need to know that it isn’t exactly written in the way you’d think. Rather than write Scandium, for example as 1s22s22p63s23p64s23d1, which would make the most sense, it is instead written with the 3 level orbitals clumped together and the four level orders clumped together, like this: 1s22s22p63s23p63d14s2. This is made even more confusing by the fact that the sequence for chromium is written differently, according to the levels that get filled up first, which makes the chromium sequence go like this: 1s22s22p63s23p63d54s1. So, the rules for filling up electrons in orbitals are that first the Periodic Table is used to find the atomic number or the total electron number. Next, fill up the 1s, 2s, 2p, 3s, 3p, 4s, 4d, and 4p orbitals except that in copper and chromium, the pattern is broken up and has the d orbital and s orbital pattern switched as was described.
ELECTRON AFFINITY The definition of electron affinity is the change in energy (as listed in kilojoules or kJ per mole) in the gaseous phase when an electron is added to the atom in order to form a negative ion. It is basically the likelihood that a neutral atom will gain an electron. It is through chemical equations that atoms gain or lose electrons. A reaction that releases energy is called an exothermic reaction, while a reaction that absorbs energy is called an endothermic reaction. Because energy is released in an exothermic reaction, the energy is given a negative sign. The opposite is true of an endothermic reaction, which is given a positive sign. When an electron is added to a neutral atom, this results in the release of energy, giving the reaction a negative sign. This holds true only for the first electro affinity so first electron affinities are negative. How it looks is this: Atom + an electron goes to a negatively charged ion plus energy (which makes it exothermic). When it comes to adding a second electron; however, there is more energy required to add an electron to what is already a negatively charged
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