1. diagonal rule 1 The Diagonal Rule A simple use of 2 quantum numbers

2. diagonal rule 2 Electrons that receive enough extra energy from the outside world can leave the atom they are in. Electrons that return to orbits they used to reside in give up the extra energy they acquired when they moved in the first place. Electronic energy given up when electrons move back into an original orbit often shows up as a specific color light. Electrons only change orbits if specific amounts (quanta) of extra energy from the outside world are involved. Electrons that leave one orbit must move to another orbit. Summary of Bohr’s Model (1913) Electrons are in different orbits at fixed distances from nucleus.

3. diagonal rule 3 Light is emitted from an atom when electrons in an atom move from an excited state configuration to the atom’s ground state configuration. The lowest orbital (energy) arrangement for the electrons around the nucleus of an atom is know as the ground state of the atom. Electron arrangements about the nucleus that are not the lowest possible energy arrangement are know as excited states. The diagonal rule helps technicians, engineers and scientists determine the ground state arrangement of electrons about the nucleus of an atom.

4. diagonal rule 4 Light is emitted from an atom when electrons in an atom move from an excited state configuration to the atom’s ground state configuration. The diagonal rule uses the first two quantum numbers The diagonal rule helps technicians, engineers and scientists determine the ground state arrangement of electrons about the nucleus of an atom.

5. diagonal rule 5 1 2 3 the principal quantum number the angular momentum (azimuthal) quantum number n l 1,01,0 2,02,0 2,12,1 Two Quantum Number Bohr Atom Model One Quantum Number Bohr Atom Model “Random House Dictionary” Note:There are only 5 words in my version of the Random House Dictionary that start with az. Can you name them? (1) the arc of the horizon measured clockwise from the south point, in astronomy, or from the north point, in navigation. (2) the angle of horizontal deviation. Azimuthal adj. Azimuth

6. diagonal rule 6 1,01,0 2,02,0 2,12,1 Each orbit is now described by two numbers. No orbit is described by the same two numbers. (There is no orbit called 0,0 or 1,1 or 2,2, etc) 1,01,0 2,02,0 2,12,1 3,03,0 Using the 2 quantum number,,(1) (2)Is there an orbit labeled 3,3. nope! (3)How many principal quantum number 4, orbits are there? Three quick questions. four4,0 and 4,1 and 4,2 and 4,3 l n,n, atom model,atom model, what would be the label for the next orbit after orbit 2,1? Two Quantum Number Bohr Atom Model

7. diagonal rule 7 1,01,0 2,02,0 2,12,1 People are now in the habit of using letters instead of numbers for the azimuthal quantum number. The letter “s” is used when the azimuthal quantum number value is 0. The letter “p” is used when the azimuthal quantum number value is 1. For example: Each orbit is now described by two numbers. The letter “d” is used when the azimuthal quantum number value is 2. The letter “f” is used when the azimuthal quantum number value is 3. Two Quantum Number Bohr Atom Model

8. diagonal rule 8 1s1s 2s2s 2p2p So we tend to describe the ground state for the nitrogen atom as 1,01,0 2,02,0 2,12,1 People also got tired of drawing the picture every time, thus a short hand notation was invented. 1s1s 2 2s2s 2 2p2p 3 this exponent just tells us how many electrons are in the orbit. Each orbit is now described by two numbers. Two Quantum Number Bohr Atom Model

9. diagonal rule 9 1,01,0 2,02,0 2,12,1 Six more quick questions. 1s1s 2 2s2s 2 2p2p 3 this exponent just tells us how many electrons are in the orbit. (1)What is the short hand notation for the ground state electron configuration of the carbon atom? (Remember that the carbon atom has 6 protons.) 1s1s 2 2s2s 2 2p2p 2 (2) What about the helium atom? (The helium atom has 2 protons.) 1s1s 2 Two Quantum Number Bohr Atom Model

10. diagonal rule 10 2p2p 1s1s 3s3s 2s2s 3p3p (3) How many: 3s orbits3p orbits3d orbits n=1 orbits are there? n=2 orbits are there? 1s orbits 2s orbits2p orbits n=4 orbits are there? 4s orbits4p orbits4d orbits4f orbits n=3 orbits are there? 1 2 3 4 Two Quantum Number Bohr Atom Model

11. diagonal rule 11 (4) How many: 3s3s3p3p3d3d n=1 electrons are possible? n=2 electrons are possible? 1s1s 2s2s2p2p n=3 electrons are possible? 4s4s4p4p4d4d4f4f 2 electrons 6 electrons( 8) ( 2) 2 electrons n=4 electrons are possible? 6 electrons10 electrons(18) 2 electrons6 electrons?(32) 2p2p 1s1s 3s3s 2s2s 3p3p 3d3d 4d4d4f4f4s4s4p4p Two Quantum Number Bohr Atom Model 1410 electrons

12. diagonal rule 12 2p2p 1s1s 3s3s 2s2s 3p3p 3d3d 4d4d4f4f4s4s4p4p 3s3s3p3p3d3d 1s1s 2s2s2p2p 4s4s4p4p4d4d4f4f 2 26 6 6 2 2 10 14 The “ground” state for the atom with atomic number 60 is (5) true or false?(6) The “ground” state for the carbon atom (atomic number 6) is true or false? 1s1s 2 2s2s 1 2p2p 3 False, the lowest energy state for the electrons of carbon is 1s1s 2 2s2s 2 2p2p 2 True, the electrons are in the orbits that represent the lowest electron energy arrangement possible for the neodymium atom

13. diagonal rule 13 2p2p 1s1s 3s3s 2s2s 3p3p 3d3d 4d4d4f4f4s4s4p4p Diagonal Rule for Filling Bohr Model Orbits 3s3s3p3p3d3d 1s1s 2s2s2p2p 4s4s4p4p4d4d4f4f 2 6 6 6 2 2 10 14 2 5s5s 2

14. diagonal rule 14