Ch 4 Arrangement of Electrons in atoms

ELECTROMAGNETIC RADIATIONsubatomic particles (electron, photon, etc) have both PARTICLE and WAVE propertiesLight is electromagnetic radiation - crossed electric and magnetic waves:Properties :Wavelength, l (nm)Frequency, n (s-1, Hz)Amplitude, Aconstant speed. c 3.00 x 108 m.s-1

7.1

Properties of WavesWavelength (l) is the distance between identical points on successive waves.Amplitude is the vertical distance from the midline of a wave to the peak or trough.7.1

Atomic Line SpectraBohrs greatest contribution to science was in building a simple model of the atom. It was based on understanding the SHARP LINE SPECTRA of excited atoms.Niels Bohr (1885-1962)(Nobel Prize, 1922)

Line Spectra of Excited AtomsExcited atoms emit light of only certain wavelengthsThe wavelengths of emitted light depend on the element.

7.3

Jellyfish lamps made with noble gases artist- Eric Ehlenberger

7.3

Uncertainty PrincipleProblem of defining nature of electrons in atoms solved by W. Heisenberg.

It is impossible to describe the exact location of an electron.

W. Heisenberg1901-1976

b. the greatest number of electrons in an energy level is indicated by the equation - 2n2II.Quantum theory

B.4 quantum numbers1.principle quantum numbera.energy level, n, 1,2,3,4,5A. ground state when electrons are in their lowest energy

2.energy sublevels and orbitala.energy states in an energy level, lb. the number of energy states = the energy leveli.1 has 1, 2 has 2 ectii.s p d f special people deserve fudge

3.orientation in spacea.s - sphericalb.p - dumbbell x,y, zc.d - 5 orientationsd.f - 7

4.spin of electronselectrons spin - must have opposite spins in order to be in same orbitalb.orbital - space occupied by a pair of electrons

7.61s

p OrbitalsThe three p orbitals lie 90o apart in space

7.6

f Orbital

principal quantum number nn = 1, 2, 3, 4, .7.6

Boundary surfaces for all orbitals of the n = 1, n = 2 and n = 3 shellsThere aren2orbitals in the nth SHELL

Electrons act as though they spin about an axis through their centers.Because there are two directions in which they can spin, the spin quantum number has 2 values The last quantum number is the spin quantum number

Orbital diagramUse lines to represent the orbital's and arrows to represent electronsH1s

Fill up electrons in lowest energy orbitals (Aufbau principle)H 1 electronHe 2 electronsLi 3 electronsBe 4 electronsB 5 electronsC 6 electrons7.7

C 6 electronsThe most stable arrangement of electrons in subshells is the one with the greatest number of parallel spins (Hunds rule).N 7 electronsO 8 electronsF 9 electronsNe 10 electrons7.7

Paramagneticunpaired electronsDiamagneticall electrons paired7.8

Electron configuration is how the electrons are distributed among the various atomic orbitals in an atom.1s17.8

Fill up electrons in lowest energy orbitals (Aufbau principle)H 1 electronH 1s1He 2 electronsHe 1s2Li 3 electronsLi 1s22s1Be 4 electronsBe 1s22s2B 5 electronsB 1s22s2 2p1C 6 electrons7.7

C 6 electronsThe most stable arrangement of electrons in subshells is the one with the greatest number of parallel spins (Hunds rule).C 1s22s2 2p2N 7 electronsN 1s22s2 2p3O 8 electronsO 1s22s2 2p4F 9 electronsF 1s22s2 2p5Ne 10 electronsNe 1s22s2 2p67.7

Noble gas notationUse the nearest noble gas that is behind the element and then add to ite.g write the noble gas notation for NaNe is the nearest noble gas its configuration is 1s2 2s2 2p6Therefore [Ne] indicates 1s2 2s2 2p6

Na would be [Ne] 3s1

What is the electron configuration and noble gas notation of Mg?Mg 12 electrons1s < 2s < 2p < 3s < 3p < 4s 1s22s2 2p63s22 + 2 + 6 + 2 = 12 electrons7.8Abbreviated as [Ne]3s2[Ne] = 1s22s22p6

What are the possible quantum numbers for the last (outermost) electron in Cl?Cl 17 electrons1s < 2s < 2p < 3s < 3p < 4s 1s22s2 2p63s2 3p52 + 2 + 6 + 2 + 5 = 17 electronsLast electron added to 3p orbitaln = 3l=p

Try These!Write the shorthand (Noble gas notation) for:CuWAu

[Ar] 4s2 3d9[Xe] 6s2 4f14 5d4[Xe] 6s2 4f14 5d9

Electron dot diagramsValence electrons those electrons in the outer most energy Level (those with the highest number)Mg121s22s2 2p63s2Mg has 2 valence electronsMg

Fe261s22s22p63s23p64s23d6Fe only has 2 valence electronsFe

S161s22s2 2p63s2 3p4S

Atomic number (Z) = number of protons in nucleus Mass number (A) = number of protons + number of neutrons = atomic number (Z) + number of neutronsIsotopes are atoms of the same element (X) with different numbers of neutrons in their nuclei2.3

2.3

6 protons, 8 (14 - 6) neutrons, 6 electrons6 protons, 5 (11 - 6) neutrons, 6 electronsDo You Understand Isotopes?2.3d.Canal rays - in 1886 Eugen Goldstein observed a cathode ray tube also generates a stream of positively charged particles

VI.Hunds rule - electrons must be placed in each orbital before pairing them upVII.Valance electrons - those in the outer most energy level- gives elements its chemical propertiesVIII.orbital notation - linesIX.Electron configuration -1s2 2s2 2p6X.Nobel gas notation - {Ar} 4s1XI.Electron dot notation - only use the valance electronOdds and ends

On page 118 13,17,19,22,24,27,29,30

*****