Atomic Theory Continued…

10.1 Rutherford’s Atom  QUESTIONS: HOW DO ELECTRONS STAY IN ORBIT? HOW COME ELECTRONS ARE NOT ATTRACTED TO THE NUCLEUS? **DO NOT COPY THIS**

10.2 Electromagnetic Radiation  Light (energy) travels in waves (TRUTH)  Electromagnetic Spectrum (p282 fig. 10.4) Energy travels in waves ○ Some we can see, some we can hear The electromagnetic spectrum illustrates all of the energy, from largest wavelength to smallest ○ Visible Spectrum Red light – lowest frequency, longest wavelength Violet Light – highest frequency, shortest wavelength

The Electromagnetic Spectrum p.284

 4 Characteristics of electromagnetic radiation (Waves): Amplitude – height of the wave measured from the origin to its peak Wavelength ( ) – distance between successive peaks of the wave

 Frequency ( ) – how fast a wave oscillates up & down – measured by the # of times a light wave completes a cycle of up & down motion in 1 sec. ○ Unit: cycles per second ○ = 1/s = s -1 = 1 Hz (hertz)  Speed (c) – light a constant speed of 3.00 x 10 8 m/s

 Relationship between wavelength & frequency: c =  1900 Max Planck There is a limit on the amounts of energy that an object emits or absorbs (quantum, fixed amount) E = h Frequency Planck’s Constant Energy

What is Planck’s constant? h = x J s ○ So small, it makes energy seem continuous……

10.3 Emission of Energy by Atoms  1905 Albert Einstein Light consists of quanta of energy that behave like tiny particles (photons) ○ Explained the photoelectric effect – certain frequencies of light can eject e - Red light does not free e - (low freq) Violet light frees e - (high freq) 1923 Arthur Compton confirmed

10.4 The energy levels of Hydrogen  Ground state – the lowest possible energy level that we can find an e - (stable)  Excited state – when e - absorbs a quantum of energy, it moves to another energy level (unstable)  Energy levels of atoms are quantized (only certain values allowed) Line spectrum – a spectrum that contains only certain colors or wavelengths – not continuous

Bohr, Quantum Mechanical Models of Atoms  1927 Niels Bohr (Bohr Model) e - move in circular orbits corresponding to the various allowed energy levels; e - have the ability to jump energy levels, releasing photons to return to ground state  Quantum Mechanical Model Bohr’s model only worked for hydrogen sort of Louis DeBroglie & Erwin Schrodinger suggested that e - act as a particle & wave ○ e - exist in orbitals, not orbits ○ Probability of where e - may be found only

10.7 The Hydrogen Orbitals  Orbitals & Energies Principle quantum numbers – (n) designates energy levels ○ Refers to a princ. energy level ○ Values are increasing in energy (n = 1,2,3,4…7) ○ Each energy level contains energy sublevels that hold e - # sub-levels = princ. quantum # (up to 4 only)

The Quantum Mechanical Atomic Model & Electron Configuration  Pauli Exclusion Principle – each orbital of each atom can only hold 2 e- of opposite spin Sublevel# OrbitalsMax # e - s12 p36 d510 f714 Aufbau Principle – e - fill orbitals that have the lowest energy level first Hund’s Rule – e - fill each orbital in a sublevel one at a time until each orbital has one e -

10.10 e- config’s & the P.T.  s,p,d,f blocks!

10.11 Atomic Properties & the P.T.  Recall chemistry is a science based on the observed properties of substances!  Atomic theory is an attempt to help us understand WHY these things occur  Properties of elements: Metals ○ Tend to lose electrons ○ Lustrous appearance ○ Ability to change shape w/o breaking (malleable, ductile) ○ Conduct heat and electricity

 Properties of non-metals Tend to gain electrons Dull Nonconductive  Properties of metalloids Exhibit the behavior of both metals and nonmetals  Trends on the P.T. Ionization energy (energy req’d to remove an e - ) increases as you go up and across the P.T. Atomic size decreases as you go up and across the P.T. Electronegativity – affinity for an e - increases as you go up and across the P.T.

 Trends on the P.T. Ionization energy (energy req’d to remove an e - ) increases as you go up and across the P.T. Atomic size decreases as you go up and across the P.T. Electronegativity – affinity for an e - increases as you go up and across the P.T.