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Atomic Structure

Atomic StructureAll matter is composed of atoms.Understanding the structure of atoms iscritical to understanding the propertiesof matter.properties of solid materials depend on the geometrical atomic arrangements, and the interactions between constituentatoms.

history of the atom460 BCDemocritus developed the idea of atoms

he pounded up materials in his pestle and mortar until he had reduced them to smaller and smaller particles which he calledATOMA (greek for indivisible)It took ~2400 years from when it was conceived to the time experimental evidence prove of the atom existence.3

history of the atom 1808John Daltonsuggested that all matter was made up of tiny spheres that were able to bounce around with perfect elasticity and called themATOMS 4

history of the atom1898Joseph John Thompson / Cambridge found that atoms could sometimes eject a far smaller negative particle which he called ELECTRON 1906 Nobel prize in Physics5History of the atom1910Ernest Rutherford / Cambridge student of Thompson

proposed a more detailed model with a central nucleus: positive charge was all in a central nucleus. With this holding the electrons in place by electrical attraction1908 Nobel prize in Chemistry61913Niels Bohr / Danish / a football fanatic

studied under Rutherford at the Victoria University in Manchester. Bohr refined Rutherford's idea by adding that the electrons were in orbits. Rather like planets orbiting the sun. With each orbit only able to contain a set number of electrons.History of the atom1922 Nobel prize in physics7Bohrs atom

Rutherfords model predicted a rainbow of colors rather than discrete lines obtained from an atomic line spectra.To explain the line spectra, Bohr proposed that electrons of specific energy moved in circular orbits around the nucleus and could not exist between these orbits.8Atomic StructureAtoms are composed of

protons positively charged particlesneutrons neutral particles

electrons negatively charged particles in orbitals surrounding the nucleus.nucleus

Atomic StructureEvery different atom has a characteristic number of protons in the nucleus.atomic number (Z) = number of protons For an electrically neutral atom, atomic number = number of electrons. Atoms with the same atomic number have the same chemical properties and belong to the same element.Atomic StructureZ ranges from 1 for hydrogen to 92 for uranium (the highest for the naturally occuring elements).

The atomic mass (A) of a specific atom: the sum of the number of protons and neutrons within the nucleus. mass number:A = Z + Nnumber of protons is the same for all atoms of a given element, number of neutrons (N) may be variable. Atomic StructureAtomic StructureThe number of protons in the nucleus of the atom is equal to the atomic number (Z). The number of electrons in a neutral atom is equal to the number of protons. The mass number of the atom (M) is equal to the sum of the number of protons and neutrons in the nucleus. The number of neutrons is equal to the difference between the mass number of the atom (M) and the atomic number (Z). Atomic Structure / isotopes

atoms of some elements have two or more different atomic masses, called isotopes. Atomic weight: Weighted average of the atomic masses of the atoms naturally occurring isotopes.Boron consists of the isotopes: 19.7% B-10 and 80.3% B-11.atomic mass A, B = (19.7 x 10)+(80.3 x 11)]/100= 10.8

Bromine isotopes: 50.5% Br-79 and 49.5% Br-81. atomic mass A, Br=[(50.5 x 79)+(49.5 x 81)]/100= 80.0

Atomic StructureIn one mole of a substance there are 6.022 x1023 (Avogadros number) atoms or molecules.Atomic weight = weight of 6.023 x 1023 atoms

For example, the atomic weight of iron is 55.85 amu/atom, or 55.85 g/mol. 1 amu/atom = 1g/mol = 1 daltonAtomic mass unit (amu): 112 of the atomic mass of the carbon C:12.011 / H:1.008 etc.Atomic Structuresubatomic particlesparticleMass (g)Charge (C/eV)Electron (e-)9.11x10-28-1.6x10-19-1Proton (p)1.67x10-24+1.6x10-19+1Neutron (n)1.67x10-2400Proton is 1837 times heavier than an electron. Neutron is 1842 times heavier than an electron.

Electron is much lighter with respect to theprotons and neutrons17Atomic StructureHELIUM ATOM+NN+--protonelectronneutronShellnucleusHe24ATOMIC MASS NUMBER = number of protons + number of neutronsATOMIC NUMBER = number of protons # electrons = # protons18LithiumProtonsNeutronsElectronsthree electronsthree protons four neutrons.Li3719BerylliumProtonsNeutronsElectronsfour electrons four protonsfive neutrons.Be4920Boronfive electronsfive protons six neutrons.ProtonsNeutronsElectronsB51121Carbonsix electronssix protons six neutrons.ProtonsNeutronsElectronsC61222Nitrogenseven electronsseven protons seven neutrons.ProtonsNeutronsElectronsN71423Oxygeneight electrons eight protons eight neutronsProtonsNeutronsElectronsO81624Fluorinenine electrons nine protons ten neutrons.ProtonsNeutronsElectronsF91925NeonProtonsNeutronsElectronsten electrons ten protons ten neutronsNe102026SodiumProtonsNeutronsElectronseleven electrons eleven protons twelve neutronsNa112327K1939U92238How many protons, neutrons and electrons?2656Al1327Ti2248FeH11Atomic structure28Ti2248

How many protons, neutrons and electrons?Atomic structure292656Fe

How many protons, neutrons and electrons?Atomic structure30Al1327

How many protons, neutrons and electrons?Atomic structure31K1939

How many protons, neutrons and electrons?Atomic structure32The charge and mass number of an electron are:charge = 0, Mass number = 1charge = -1, Mass number = 0charge = +1, Mass number = 1charge = +1, Mass number = 0

The charge and mass number of a neutron are?charge = +1, Mass number = 1 charge = 0, Mass number = 1 charge = +1, Mass number = 0 charge = -1, Mass number = 0Atomic structureWhich of the following has 25 protons and 31 neutrons?

56Mn56Ga25Ga31Mn56Ba Atomic structureWhy does chlorine have an atomic mass of 35.5, which is not a whole number?Chlorine contains an extra electron which makes it weigh more than 35.Chlorine contains 17 protons and 18.5 neutronsChlorine normally exists in an excited state, and so it weighs more than 35.The chlorine was not pure when its atomic mass was measured.Chlorine, as found in nature, contains a mixture of the isotopes 35Cl and 37Cl, in such proportions as to give an average atomic mass of 35.5Atomic structure The two main parts of an atom are?

a) nucleus and electron energy levelsb) nucleons and protonsc) oxidation number and valenced) protons and neutronse) protons and electrons

Atomic structure36The nucleus of the element having atomic number 25 and atomic weight 55 will contain?

25 protons and 30 neutrons 30 protons and 25 neutrons 55 protons 55 neutrons

Atomic structure37A beryllium atom has 4 protons, 5 neutrons, and 4 electrons. What is the mass number of this atom?

458913Atomic structure38The smallest particle into which an element can be divided and still have the properties of that element a) nucleus b) electron c) atom d) neutron

How would you describe the nucleus?a) dense, positively charged b) mostly empty space, positively charged c) tiny, negatively charged d) dense, negatively chargedAtomic structureWhere are electrons likely to be found?a) in the nucleus b) in electron clouds c) mixed throughout an atom d) in definite paths

Every atom of a given element has the same number ofa) protons b) neutrons c) electrons d) isotopesAtomic structureWhat is the meaning of the word atom?a) dividable b) invisible c) hard particles d) not able to be divided

Which statement is true about isotopes of the same element?a) They have the same number of protons b) They have the same number of neutronsc) They have a different atomic number d) They have the same massAtomic structureWhich has the least mass in an atom?a) nucleus b) proton c) neutron d) electronIf an isotope of uranium, uranium-235, has 92 protons, how many protons does the isotope uranium-238 have?a) 92 b) 95 c) 143 d) 146Atomic structureA carbon atom with 6 protons, 6 electrons, and 6 neutrons would have a mass number ofa) 6b) 12 c) 15 d) 18

The number at the top is thea) atomic number b) element name c) atomic mass d) chemical symbolAtomic structureHow many electrons does a neutral Cl atom contain?16171819

What is the difference between atomic mass and atomic weight?Atomic structureCl1735Atomic StructureNeutral atoms have the same numberof protons and electrons.

Ions are charged atoms.cations have more protons than electrons and are positively charged

anions have more electrons than protons and are negatively chargedIf a neutral atom looses one or more electronsit becomes a cation.If a neutral atom gains one or more electronsit becomes an anion.Na11 protons11 electronsNa+11 protons10 electronsCl17 protons17 electronsCl-17 protons18 electronsAtomic Structuree- ++ e- 46

electrons are assumed to revolve around the atomic nucleus in discrete orbitals, and the position of any particular electron is more or less well defined in terms of its orbital.

Electrons are permitted to have only specific values of energy.Bohr Atomic model

Bohr Atomic model

excitation vs relaxation

An electron may change energy by making a quantum jump either to an higher energy (with absorption of energy) or to a lower energy (with emission of energy). excitationrelaxationQuantum MechanicsUnfortunately, extremely small particles (electrons) do not follow the laws of classical (Newtonian) physics. The new physics that mathematically treats small particles is called Quantum Mechanics.

50

electron distributionwave-mechanical model an electron is no longer treated as a particle moving in a discrete orbital; electron is considered to exhibit both wavelike and particle-like characteristics.The position of an electron is described by a probability distribution // electron cloud.Quantum Mechanics

Wave behavior is described with the wave function , incorporating the wave and particle features of electrons (Erwin Schrdinger)

The probability of finding an electron in a certain area of space is proportional to 2 electron density.

Austrian; 1933 Nobel prize in physics

Quantum MechanicsHeisenbergs uncertainty principlemore precisely the position of some particle is determined, the less precisely its momentum can be knownA macroscale analogy

High Shutter SpeedLow Shutter SpeedCan judge location,Can judge speed,but not speed.But not locationwe cannot precisely measure the momentum and the position of an electron at the same time. As the momentum of the electron is more and more certain, the position of the electron becomes less and less certain, and vice versa.

n = 2.5 cannot exist as a principal quantum number. There must be an integral number of wavelengths (n) in order for an electron to maintain a standing wave. If there were to be partial waves, the whole and partial waves would cancel each other out and the particle would not move. Heisenbergs uncertainty principleQuantum Mechanics

The Schrdinger equation specifies possible energy states an electron can occupy.

The energy states and wave functions are characterized by a set of quantum numbers.

Instead of orbits in the Bohr model, quantum numbers and wave functions describe atomic orbitals.

every electron in an atom is characterized by four quantum numbers. There are three quantum numbers necessary to describe an atomic orbital.The principal quantum number (n) designates sizeThe angular moment quantum number (l) describes shapeThe magnetic quantum number (ml) specifies orientationquantum numbersPrincipal Quantum Number (n)

designates the size of the orbital.Larger values of n correspond to larger orbitals.The allowed values of n are integers: 1, 2, 3 and so forth.A collection of orbitals with the same value of n is frequently called a shell.nKLMNOP.......123456Angular moment Quantum Number (l)

signifies the subshell describes the shape of the orbital.l values range from 0 to n 1Example: If n = 2, l can be 0 or 1.n123456lsubshell012345spdfghenergy state1357911Magnetic Quantum Number (ml)

describes the orientation of the orbital in space.ml are integers that depend on l: l,0,+lml identifies # of energy states for each subshellFor an s subshell: a single energy state For p, d, and f subshells: 3, 5, and 7 energy states

Principal Quantum No: nShellSubshell l No. of energy States: mlNumber of ElectronsPer SubshellPer Shell1Ks /01 / 0222Ls / 01 / 028p / 13 / -1,0,+163Ms / 01 / 0218p / 13 / -1,0,+16d / 25 / -2,-1,0,+1,+2104Ns / 01 / 0232p / 13 / -1,0,+16d / 25 / -2,-1,0,+1,+210f / 37 / -3,-2,-1,0,+1,+2,+3145Os / 01 / 0250p / 13 / -1,0,+16d / 25 / -2,-1,0,+1,+210f / 37 / -3,-2,-1,0,1,2,314g / 49 / -4,-3,-2,-1,0,+1,+2,+3,+4186Ps / 01 / 0272p / 13 / -1,0,+16d / 25 / -2,-1,0,+1,+210f / 37 / -3,-2,-1,0,1,2,314g / 49 / -4,-3,-2,-1,0,1,2,3,418h / 511 / -5,-4,-3,-2,-1,0,+1,+2,+3,+4,+522Number of available electron states for initial shells and subshellsAn s subshell has one orbital which is spherically shaped.

If you were to measure where the electron was within an s subshell many, many times and plot the results on a graph you would get something like this.Atomic orbitalsAtomic Orbitals

p orbitals: a dumbbell shape with electrons on either side of the nucleus in tear drop shaped lobes

Three orientations:l = 1 (as required for a p orbital)ml = 1, 0, +163Atomic Orbitals

The d orbitals:

Five orientations:l = 2 (as required for a d orbital)ml = 2, 1, 0, +1, +264d-orbitals are followed by the seven f-orbitals.

Atomic orbitals7 orientations:l = 3 (as required for a d orbital)ml = -3, 2, 1, 0, +1, +2, +3Quantum Numbers

To summarize quantum numbers:principal (n) sizeangular (l) shapemagnetic (ml) orientation

electron spin (ms) direction of spinRequired to describe an atomic orbitalRequired to describe an electron in an atomic orbital2pxprincipal (n = 2)angular momentum (l = 1)related to the magnetic quantum number (ml )

66Electron Spin Quantum Number (ms)

used to specify an electrons spin.

There are two possible directions of spin.

Allowed values of ms are + and .

67Pauli exclusion principleNo Two Electrons in an Atom Can Have the Same Four Quantum Numbers; the same values for n, l, ml, and ms.

Although the first three quantum numbers identify a specific orbital and may have the same values, the fourth is significant andmust have opposite spins.

a set of quantum numbers is specific to a certain electron.Quantum numbersAn electron with n = 2, = 1, ml=1, and ms=+1/2 is found in the same atom as a second electron with n=2, =1, and ml=1.

What is the spin quantum number for the second electron?

First electron: n = 1, = 1, ml = 1, ms = +1/2Second electron: n = 1, = 1, ml = 1, ms =?

Since the first three quantum numbers are identical for these two electrons, we know that they are in the same orbital. As a result, the spin quantum number for the second electron cannot be the same as the spin quantum number for the first electron. This means that the spin quantum number for the second electron must be ms=1/2.Quantum numbersAn electron with n = 5, = 4, ml=3, and ms=1/2 is found in the same atom as a second electron with n=5, =4, and ml=3.

What is the spin quantum number for the second electron?

Quantum numbersFirst electron: n = 5, = 4, ml = 3, ms = 1/2Second electron: n = 5, = 4, ml = 3, ms =?

Since the first three quantum numbers are identical for these two electrons, we know that they are in the same orbital. As a result, the spin quantum number for the second electron cannot be the same as the spin quantum number for the first electron. This means that the spin quantum number for the second electron must be ms=+1/2.Quantum numbersCan an electron with n = 1, = 0, ml = 0, and ms = +1/2 exist in the same atom as a second electron with n=2, =0, ml=0, and ms=+1/2?

Quantum numbersPauli exclusion principleFirst electron: n = 1, = 0, ml = 0, ms = +1/2Second electron: n = 2, = 0, ml = 0, ms = +1/2

Since these two electrons are in different orbitals, they occupy different regions of space within the atom.

As a result, their spin quantum numbers can be the same, and thus these two electrons can exist in the same atom.Atomic structureMaximum number of electrons in a subshell with l = 3 and n = 4 is

101214161875The lowest principal quantum number for an electron is?

01234

Atomic structure76Which sublevel can by occupied by a maximum of 10 electrons?

spdf

Atomic structure77Atomic structureThe K, L and M shells of an atom are full. Its atomic number is_______.

18 20 10 1278State whether an electron can be described by each of the following sets of quantum number. If a set is not possible, state why not.n = 2, l = 1, ml = -1

n = 1, l = 1, ml = +1

n = 4, l = 3, ml = +3

n = 3, l = 1, ml = -3Atomic structureState whether an electron can be described by each of the following sets of quantum number. If a set is not possible, state why not.n = 2, l = 1, ml = -1l: 0/1, ml: -1/0/1

n = 1, l = 1, ml = +1l: 0, ml: 0

n = 4, l = 3, ml = +3l: 0,1,2,3; ml: -3,-2,-1,0,1,2,3n = 3, l = 1, ml = -3l:0,1,2;ml: -2,-1,0,1,2Atomic structureReplace the question marks by suitable responses in the following quantum number assignments.n = 3, l = 1, ml = ?n = 4, l = ?, ml = -2n = ?, l = 3, ml = ?

Atomic structureReplace the question marks by suitable responses in the following quantum number assignments.n = 3, l = 1, ml = -1,0,1n = 4, l = 2, ml = -2n = 4, l = 3, ml = -3,-2,-1,0,1,2,3

Atomic structureProvide the three quantum numbers describing each of the three p orbitals in the 2p subshell.nlml2px

2py

2pz

Atomic structureProvide the three quantum numbers describing each of the three p orbitals in the 2p subshell.nlml2px2102py2112pz21-1

Atomic structureFor n = 1, determine the possible values of l. For each value of l, assign the appropriate letter designation & determine the possible values of ml.n = 1l = 0 ml= 01ml= -1,0,1Atomic structureHow many orbitals in shell n = 1?

How many electrons possible?

Atomic structureFor n = 2, determine the possible values of l. For each value of l, assign the appropriate letter designation & determine the possible values of ml.

How many orbitals in shell n = 2?

How many electrons possible?Atomic structure

Principal Quantum No: nShellSubshell l No. of energy States: ml2Ls / 01 / 0p / 13 / -1,0,+1Principal Quantum No: nShellSubshell l Number of ElectronsPer SubshellPer Shell2Ls / 028p / 16Atomic structureFor n = 3, determine the possible values of l. For each value of l, assign the appropriate letter designation & determine the possible values of ml.

How many orbitals in shell n = 2?

How many electrons possible?

Atomic structure

Principal Quantum No: nShellSubshell l No. of energy States: ml3Ms / 01 / 0p / 13 / -1,0,+1d / 25 / -2,-1,0,+1,+2Principal Quantum No: nShellSubshell l Number of ElectronsPer SubshellPer Shell3Ms / 0218p / 16d / 210Atomic structureFor n = 4, determine the possible values of l. For each value of l, assign the appropriate letter designation & determine the possible values of ml.

Atomic structurePrincipal Quantum No: nShellSubshell l No. of energy States: ml4Ns / 01 / 0p / 13 / -1,0,+1d / 25 / -2,-1,0,+1,+2f / 37 / -3,-2,-1,0,+1,+2,+3Atomic structureProvide the four quantum numbers describing each of the two electrons in the 3s orbital.nlml ms

Atomic structureProvide the four quantum numbers describing each of the two electrons in the 3s orbital.nlml ms

300 +1/2

300 -1/2

Atomic structureQuantum Numbers: A Macroscale Analogyn- indicates which train (shell)

l- indicates which car (subshell)

ml- indicates which row (orbital)

ms- indicates which seat (spin)

No two people can have exactly the same ticket (sit in the same seat).

Electron energy stateselectrons have discrete energy states they fill up the lowest possible energy states in the electron shells and subshells, When all the electronsoccupy the lowest possible energies in accord with the foregoing restrictions, an atom is said to bein its ground state.

Energy states for a Na atomMost elements: Electron configuration not stable!Electron configurationsElectron configuration(stable)... ... 1s22s22p63s23p6(stable)... 1s22s22p63s23p63d104s24p6(stable)Atomic # 18...36Element1s1 1Hydrogen1s22Helium1s22s1 3Lithium1s22s24Beryllium1s22s22p15Boron1s22s22p26Carbon...1s22s22p6(stable)10Neon1s22s22p63s111Sodium1s22s22p63s2 12Magnesium1s22s22p63s23p113Aluminum...Argon...Krypton97Electron ConfigurationsValence electrons those in unfilled shellsFilled shells more stableValence electrons are most available for bonding and tend to control the chemical, electrical, thermal, optical properties example: C (atomic number = 6)

1s2 2s2 2p2

valence electrons98Electron Configurationsthe full electronic configuration of an element is 1s22s22p5

How many electrons does it have in its out shell?

the full electronic configuration of an element.1s22s22p5

What is its atomic number?99Electronic ConfigurationsFe-atomic # =261s2s2pK-shell n = 1L-shell n = 23s3pM-shell n = 33d4s4p4dEnergyN-shell n = 41s2 2s2 2p6 3s2 3p63d 6 4s2100Valence electronsElement symbolAtomic numbere-configuration# of valence electronsH11s11He21s22Li31s22s11Be41s22s22B51s22s22p13C61s22s22p24N71s22s22p35O81s22s22p46F91s22s22p57Ne101s22s22p68101Order of Subshell FillingThe electron configurations of the first ten elements illustrate this point.

Electron configurations for common elementsShells and subshells

In multi-electron atoms, the energies of the atomic oorbitals are split.

Splitting of energy levels refers to the splitting of a shell (n=3) into subshells of different energies (3s, 3p, 3d)104Splitting of Shells into subshells

2nd shell (n = 2) 3d subshell (n = 3; l = 2)2p subshell (n = 2; l = 1)3rd shell (n = 3)2s subshell (n = 2; l = 0)3p subshell (n = 3; l = 1)3s subshell (n = 3; l = 0)105Electron Configurations

rules for electron configurations:Electrons will reside in the lowest possible energy orbitalsEach orbital can accommodate a maximum of two electrons.Electrons will not pair in degenerate orbitals if an empty orbital is available.Orbitals will fill in the order ..3p6/4s2/3d10/4p6/5s2/4d10/5p6/6s2/4f14/5d10/6p6/7s2

106Energy Level Diagram of a Many-Electron Atom ArbitraryEnergy Scale1818328821s2s 2p3s 3p4s 4p 3d 5s 5p 4d6s 6p 5d 4fNUCLEUS107Original reference: Pimental, Chemistry An Experimental Science, (CHEM Study), 1969, page 266.Electron Configurations

The electron configuration describes how the electrons are distributed in the various atomic orbitals.In a ground state hydrogen atom, the electron is found in the 1s orbital.1s1principal (n = 1)angular momentum (l = 0)number of electrons in the orbital or subshell1s2s2p2p2pEnergyThe use of an up arrow indicates an electron with ms = + Ground state electron configuration of hydrogen108Electron Configurations

Pauli exclusion principle: no two electrons in an atom can have the same four quantum numbers.1s21s2s2p2p2pEnergyThe ground state electron configuration of heliumQuantum numberPrincipal (n)Angular moment (l)Magnetic (ml)Electron spin (ms)100+ 100 describes the 1s orbitaldescribes the electrons in the 1s orbital110Electron Configurations

The Aufbau principle states that electrons are added to the lowest energy orbitals first before moving to higher energy orbitals.1s22s11s2s2p2p2pEnergyThe ground state electron configuration of LiThe 1s orbital can only accommodate 2 electrons (Pauli exclusion principle)The third electron must go in the next available orbital with the lowest possible energy.Li has a total of 3 electrons111Electron Configurations

1s2s2p2p2pEnergy1s22s2The ground state electron configuration of BeBe has a total of 4 electrons112Electron Configurations

1s2s2p2p2pEnergyThe ground state electron configuration of B1s22s22p1B has a total of 5 electrons113Electron Configurations

Hunds rule, the most stable arrangement of electrons is the one in which the number of electrons with the same spin is maximized.C has a total of 6 electrons1s22s22p21s2s2p2p2pEnergyThe ground state electron configuration of CThe 2p orbitals are of equal energy, or degenerate.

Put 1 electron in each before pairing (Hunds rule).114Electron Configurations

1s22s22p31s2s2p2p2pEnergyThe ground state electron configuration of NThe 2p orbitals are of equal energy, or degenerate.

Put 1 electron in each before pairing (Hunds rule).N has a total of 7 electrons115Electron Configurations

1s22s22p41s2s2p2p2pEnergyThe ground state electron configuration of OO has a total of 8 electronsOnce all the 2p orbitals are singly occupied, additional electrons will have to pair with those already in the orbitals.116Electron Configurations

1s22s22p51s2s2p2p2pEnergyThe ground state electron configuration of FF has a total of 9 electronsWhen there are one or more unpaired electrons, as in the case of oxygen and fluorine, the atom is called paramagnetic.117Electron Configurations

1s22s22p61s2s2p2p2pEnergyThe ground state electron configuration of NeNe has a total of 10 electronsWhen all of the electrons in an atom are paired, as in neon, it is called diamagnetic.118 Worked ExampleWrite the electron configuration and give the orbital diagram of a calcium (Ca) atom (Z = 20).Solution Ca1s22s22p63s23p64s2Z = 20, Ca has 20 electrons. Each s subshell can contain a maximum of two electrons, whereas each p subshell can contain a maximum of six electrons.

1s22s22p63s23p64s2Remember that the 4s orbital fills before the 3d orbitals.electron configuration for an arsenic atom (Z = 33) in the ground state.Solution As[Ar]4s23d104p3Z = 18 for Ar.The order of filling beyond the noble gas core is 4s, 3d, and 4p. Fifteen electrons go into these subshells because there are 33 18 = 15 electrons in As beyond its noble gas core.

222266310Arsenic is a p-block element; therefore, we should expect its outermost electrons to reside in a p subshell. Worked ExampleAl1327Number of Energy Levels: 3 First Energy Level: 2 Second Energy Level: 8 Third Energy Level: 3 1s22s22p63s23p1electron configuration?121K1939Number of Energy Levels: 4 First Energy Level: 2 Second Energy Level: 8 Third Energy Level: 8 Fourth Energy Level: 1 1s22s22p63s23p64s1electron configuration?122electron configuration?Ti2248Number of Energy Levels: 4 First Energy Level: 2 Second Energy Level: 8 Third Energy Level: 10 Fourth Energy Level: 2 1s22s22p63s23p64s23d2123Cr2452Number of Energy Levels: 4 First Energy Level: 2 Second Energy Level: 8 Third Energy Level: 13 Fourth Energy Level: 1 1s22s22p63s23p64s13d5electron configuration?124Mn2555Number of Energy Levels: 4 First Energy Level: 2 Second Energy Level: 8 Third Energy Level: 13 Fourth Energy Level: 2 1s22s22p63s23p64s23d5electron configuration?1252656FeNumber of Energy Levels: 4 First Energy Level: 2 Second Energy Level: 8 Third Energy Level: 14 Fourth Energy Level: 2 1s22s22p63s23p64s23d6electron configuration?126Cu2964Number of Energy Levels: 4 First Energy Level: 2 Second Energy Level: 8 Third Energy Level: 18 Fourth Energy Level: 1 1s22s22p63s23p64s13d10electron configuration?127Zn3064Number of Energy Levels: 4 First Energy Level: 2 Second Energy Level: 8 Third Energy Level: 18 Fourth Energy Level: 2 1s22s22p63s23p64s23d10electron configuration?128They occupy the outermost shell. They participate in the bonding between atomsThey dictate the physical and chemical properties

if the outermost or valence electron shell are completely filled: stable electron configurations

occupation of the s and p states for the outermost shell by a total of eight electrons, in neon (Ne), argon (Ar), and krypton (Kr); inert, or noble, gases, which are virtually unreactive chemically.Valence electronsunfilled valence shells assume stable electron configurations by gaining or losing electrons to form charged ions, or by sharing electrons with other atoms.

This is the basis for some chemical reactions, and also for atomic bonding in solidsValence electronsUnder special circumstances, the s and p orbitals combine to form hybrid spn orbitals, where n indicates the number of p orbitals involved, which may have a value of 1, 2, or 3. The IIIA, IVA, and VA group elements of the periodic table often form these hybrids. The driving force for the formation of hybrid orbitals is a lower energy state for the valence electrons. For carbon the sp3 hybrid is of primary importance in organic and polymer chemistries.Valence electronss- and p-orbitals

Aufbau Principle: filling orbitals1s2s2pn = 1l = 0ml = 0n = 2l = 0ml = 0n = 2l = 0ml = 0ml = 1ml = -1H: 1s1132s- and p-orbitals

Aufbau Principle: filling orbitals1s2s2pn = 1l = 0ml = 0n = 2l = 0ml = 0n = 2l = 0ml = 0ml = 1ml = -1He: 1s2133s- and p-orbitals

Aufbau Principle: filling orbitals1s2s2pn = 1l = 0ml = 0n = 2l = 0ml = 0n = 2l = 0ml = 0ml = 1ml = -1Li: 1s2 2s1134s- and p-orbitals

Aufbau Principle: filling orbitals1s2s2pn = 1l = 0ml = 0n = 2l = 0ml = 0n = 2l = 0ml = 0ml = 1ml = -1Be: 1s2 2s2135s- and p-orbitals

Aufbau Principle: filling orbitals1s2s2pB: 1s2 2s22p1coreclosed shellopen shell: valence electrons136s- and p-orbitals

Aufbau Principle: filling orbitalsHunds rule: maximum number of unpaired electrons is the lowest energy arrangement.1s2s2pC: 1s2 2s22p2137Hunds ruleelectrons fill orbitals one at a time.

we must fill each shell with one electron each before starting to pair them up.

the charge of an electron is negative and electrons repel each other. An electron will try to create distance between itself and other electrons by staying unpaired. This further explains why the spins of electrons in an orbital are opposite (i.e. +1/2 and -1/2).s- and p-orbitals

Aufbau Principle: filling orbitals1s2s2pN: 1s2 2s22p3O: 1s2 2s22p4139s- and p-orbitals

Aufbau Principle: filling orbitals1s2s2pF: 1s2 2s22p5Ne: 1s2 2s22p6140s- and p-orbitals

Aufbau Principle: filling orbitalsNa: 1s22s22p63s1or [Ne]3s1Mg: 1s22s22p63s2or [Ne]3s2P: [Ne]3s23p3Ar: [Ne]3s23p6141Which one of the following is a proper orbital configuration?

electron configuration?

Which one of the following is a proper orbital configuration?electron configuration?

beyond the d-orbitals

lanthanidesactinidess-groupsp-groupsd-transition elementsf-transition elementsgroupperiod1s2

2s2/2p6

3s2/3p6/

4s2/3d10/4p6

5s2/4d10/5p6/

6s2/4f14/5d10/6p6

144Organisation of the periodic table

Organisation of the periodic table

Organisation of the periodic table

Organisation of the periodic table

Organisation of the periodic table

Give electron configurations for the Fe3+and S2- ions.

electron configuration?The Fe3+ ion is an iron atom that has lost three electrons. Since the electron configuration of the Fe atom is 1s22s22p63s23p63d64s2, the configuration for Fe3+ is 1s22s22p63s23p63d5.

The S2- ion a sulfur atom that has gained two electrons. Since the electron configuration of the S atom is 1s22s22p63s23p4, the configuration for S2- is 1s22s22p63s23p6.electron configuration?Give the electron configurations for the following ions?Fe2+[Ar] 3d64s2 -2 electronsAl3+[Ne] 3s23p1 -3 electrons Cu+[Ar] 3d104s1 -1 electronBa2+[Xe] 6s2 -2 electrons Br-[Ar] 3d104s24p5 +1 electronO2-[He] 2s22p4 +2 electronselectron configuration?Which of the following electron configurations is an inert gas, a halogen, an alkali metal, an alkaline earth metal, a transition metal?

a)1s22s22p63s23p63d74s2b)1s22s22p63s23p6c)1s22s22p5d)1s22s22p63s2e)1s22s22p63s23p63d24s2f)1s22s22p63s23p64s1electron configuration?The halogens (group 7A, or group 17, of the periodic table) all have similar chemical properties (for example, forming singly charged negative ions). What aspect of their electron configurations leads to these elements having such similarities?

They all have a complete 1s2 shell at the lowest energy levelThey all have an identical Ns2Np5 configuration for their valence electrons (N is any whole number).They all have p electrons in their outermost shell.They all have an odd number of protons.They all have an even number of neutrons. electron configuration?