1 Electronic Structure of Atoms & Periodic Table Chapter 4 CHEMISTRY - DACS 1232 Fakulti Kejuruteraan Mekanikal, UTeM Lecturer: IMRAN SYAKIR BIN MOHAMAD MOHD HAIZAL BIN MOHD HUSIN NONA MERRY MERPATI MITAN

2 Quantum Numbers Principal quantum number – ( n ) Angular momentum quantum number – ( l ) Magnetic quantum number – ( m l ) Spin quantum number – ( m s )

3 Quantum Numbers (n, l, m l, m s ) principal quantum number n n = 1, 2, 3, 4, …. n=1 n=2 n=3 distance of e - from the nucleus

4 angular momentum quantum number l for a given value of n, l = 0, 1, 2, 3, … n-1 n = 1, l = 0 n = 2, l = 0 or 1 n = 3, l = 0, 1, or 2 Shape of the “volume” of space that the e - occupies l = 0 s orbital l = 1 p orbital l = 2 d orbital l = 3 f orbital Quantum Numbers(n, l, m l, m s )

5 l = 0 (s orbitals) l = 1 (p orbitals)

6 l = 2 (d orbitals)

7 magnetic quantum number m l for a given value of lm l = -l, …., 0, …. +l orientation of the orbital in space for l = 0 (s orbital) m l = 0 if l = 1 (p orbital), m l = -1, 0, or +1 if l = 2 (d orbital), m l = -2, -1, 0, +1, or +2 Quantum Numbers (n, l, m l, m s )

8 m l = -1m l = 0m l = 1 m l = -2m l = -1m l = 0m l = 1m l = 2

9 spin quantum number m s m s = +½ or -½ Quantum Numbers (n, l, m l, m s ) m s = -½m s = +½ Experimental arrangement for demo the spinning motion of electrons Q & A

10 Existence (and energy) of electron in atom is described by its unique Quantum Numbers Pauli exclusion principle No two electrons in an atom can have the same four quantum numbers. Quantum Numbers (n, l, m l, m s )

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12 Quantum Numbers (n, l, m l, m s ) Shell – electrons with the same value of n Subshell – electrons with the same values of n and l Orbital – electrons with the same values of n, l, and m l How many electrons can an orbital hold?

13 How many 2p orbitals are there in an atom? How many electrons can be placed in the 3d subshell? Q & A

14 Electron configuration is how the electrons are distributed among the various atomic orbitals in an atom. 1s 1 principal quantum number n angular momentum quantum number l number of electrons in the orbital or subshell Orbital diagram H 1s 1

15 Order of orbitals (filling) in multi-electron atom 1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p < 5s < 4d < 5p < 6s “Fill up” electrons in lowest energy orbitals (Aufbau principle)

16 H 1 electronH 1s 1 Li 3 electronsLi 1s 2 2s 1 B 5 electronsB 1s 2 2s 2 2p 1 C 6 electronsC 1s 2 2s 2 2p 2

17 The most stable arrangement of electrons in subshells is the one with the greatest number of parallel spins (Hund’s rule). N 7 electrons N 1s 2 2s 2 2p 3 O 8 electronsO 1s 2 2s 2 2p 4 F 9 electronsF 1s 2 2s 2 2p 5 Ne 10 electronsNe 1s 2 2s 2 2p 6

18 What is the electron configuration of Mg? What are the possible quantum numbers for the last (outermost) electron in Cl?

19 Outermost subshell being filled with electrons

20 Paramagnetic unpaired electrons 2p Diamagnetic all electrons paired 2p

21 Name the orbital described by the following quantum numbers : a.n = 3, l = 0 b.n = 3, l = 1 c.n = 3, l = 2 d.n = 5, l = 0 Q & A session

22 Give the n and l values for the following orbital a. 1s b. 3s c. 2p d. 4d e. 5f What and the possible m l values for the following types of orbital? a. s b. p c. d d. f Q & A session

23 How many possible orbital are there for n = a. 4 b. 10 How many electrons can inhabit all of the n = 4 orbital? Place the following orbital in order of increasing energy: 1s, 3s, 4s, 6s, 3d, 4f, 3p, 7s, 5d, 5p Q & A session

24 Write electron configurations for the following atoms: a. H b. Li + c. N d. F - e. Ca Q & A session

25 Draw an orbital diagrams for atoms with the following electron configurations: 1s 2 2s 2 2p 6 3s 2 3p 3 Q & A session

26 Periodic Table

27 When the Elements Were Discovered

28 ns 1 ns 2 ns 2 np 1 ns 2 np 2 ns 2 np 3 ns 2 np 4 ns 2 np 5 ns 2 np 6 d1d1 d5d5 d 10 4f5f Ground State Electron Configurations of the Elements

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30 Classification of the Elements

31 Electron Configurations of Cations and Anions Na [Ne]3s 1 Na + [Ne] Ca [Ar]4s 2 Ca 2+ [Ar] Al [Ne]3s 2 3p 1 Al 3+ [Ne] Atoms lose electrons so that cation has a noble-gas outer electron configuration. H 1s 1 H - 1s 2 or [He] F 1s 2 2s 2 2p 5 F - 1s 2 2s 2 2p 6 or [Ne] O 1s 2 2s 2 2p 4 O 2- 1s 2 2s 2 2p 6 or [Ne] N 1s 2 2s 2 2p 3 N 3- 1s 2 2s 2 2p 6 or [Ne] Atoms gain electrons so that anion has a noble- gas outer electron configuration. Of Representative Elements

Cations and Anions Of Representative Elements

33 Ion charges

34 Na + : [Ne]Al 3+ : [Ne] F - : 1s 2 2s 2 2p 6 or [Ne] O 2- : 1s 2 2s 2 2p 6 or [Ne]N 3- : 1s 2 2s 2 2p 6 or [Ne] Na +, Al 3+, F -, O 2-, and N 3- are all isoelectronic with Ne What neutral atom is isoelectronic with H - ?

35 Electron Configurations of Cations of Transition Metals When a cation is formed from an atom of a transition metal, electrons are always removed first from the ns orbital and then from the (n – 1)d orbitals. Fe: [Ar]4s 2 3d 6 Fe 2+ : [Ar]4s 0 3d 6 or [Ar]3d 6 Fe 3+ : [Ar]4s 0 3d 5 or [Ar]3d 5 Mn: [Ar]4s 2 3d 5 Mn 2+ : [Ar]4s 0 3d 5 or [Ar]3d 5