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1、17 June 2019,Y2 Electron arrangement,1,Electron shells,17 June 2019,1,Atomic Structure Electron arrangement Y12,17 June 2019,Y2 Electron arrangement,2,Electrons,Electrons can be found in electron shells or orbits These shells are also called energy levels Electrons exist in a stable condition when t
2、hey are fixed in an energy level Electron shells are number and are known as the principal quantum number 1,2,3 What do these numbers correspond to?,17 June 2019,Atomic Structure Electron arrangement Y12,2,17 June 2019,Y2 Electron arrangement,3,Shapes of orbitals,s orbital is the shape of a sphere,1
3、7 June 2019,Atomic Structure Electron arrangement Y12,3,17 June 2019,Y2 Electron arrangement,4,p orbital,The p orbital is called a dumbbell,17 June 2019,Atomic Structure Electron arrangement Y12,4,17 June 2019,Y2 Electron arrangement,5,d orbital,17 June 2019,Atomic Structure Electron arrangement Y12
4、,5,17 June 2019,Y2 Electron arrangement,6,Electron sub shells,The arrangement of atoms in the periodic table shows the different energy levels of the electrons In period 2 we can see that the electrons exist in 2 sub shells There are 4 different types of sub shells called orbitals These are s, p,d a
5、nd f,17 June 2019,Atomic Structure Electron arrangement Y12,6,17 June 2019,Y2 Electron arrangement,7,Electron sub shells,Look at the periodic table Period 1 contains 2 electrons Period 2 contains 8 electrons This relates to the electron orbits But what happens in period 2? This is separated into 2 a
6、nd 6 The same happens for period 3 What about period 4?,17 June 2019,Atomic Structure Electron arrangement Y12,7,17 June 2019,Y2 Electron arrangement,8,Orbitals,An s subshell contains 1 orbital A p subshell contains 3 orbitals What does a d subshell contain? An electron orbital represents a region o
7、f space where the electrons are likely to be found (about 90%) probability Each orbital has a 3 dimensional shape but do not have exact boundaries, so they can be fuzzy Often called charge-clouds,17 June 2019,Atomic Structure Electron arrangement Y12,8,17 June 2019,Y2 Electron arrangement,9,Filling
8、electron shells,Look at each atom and its position in order to write out the electron configuration for the 1st 20 elements For example Hydrogen 1s1 Helium 1s2 Lithium 1s2 2s1 Continue for the other atoms,17 June 2019,Atomic Structure Electron arrangement Y12,9,17 June 2019,Y2 Electron arrangement,1
9、0,Ionisation energy,Ionisation energy explains how we know that electrons are in subshells 1st ionisation energy for an element is the amount of energy that is needed to remove one electron from each atom in one mole of atoms of an element in the gaseous state What is the 2nd ionisation energy?,17 J
10、une 2019,Atomic Structure Electron arrangement Y12,10,17 June 2019,Y2 Electron arrangement,11,Summary,We can describe electron sub shells Give the electron configuration for sodium (Na) 1s2,2s2,2p6,3s2,3p4 is the electron configuration for which atom? From the electron configuration decide which group and which period this element belongs to,