Chapter 8 Atoms and Periodic Properties

2 Revised Homework for Chap 8 Read p 203 – 215, 218 – 225 (omit Wave Mechanics, The Quantum Mechanics Model, and Electron Configuration) Applying the Concepts # 1 – 17,

3 Line Emission Spectrum of Hydrogen Atoms Atomic Emission Spectrum (Line spectrum)

4 7.3

5 Chemistry in Action: Element from the Sun In 1868, Pierre Janssen detected a new dark line in the solar emission spectrum that did not match known emission lines In 1895, William Ramsey discovered helium in a mineral of uranium (from alpha decay). Mystery element was named Helium

6 1.e - can only have specific (quantized) energy values 2.light is emitted as e - moves from one energy level to a lower energy level Bohr’s Model of the Atom (1913) E n = E1E1 n2n2 n (quantum number) = 1,2,3,… 7.3

7 E = hf 7.3 R O Y G B I V Lowenergy,lowfrequencyHighenergy,highfrequency

8 Why is e - energy quantized?

9 Standing or stationary waves Fig nodes

10 De Broglie (1923) reasoned that e - is both a particle and a matter wave! v = velocity of e - m = mass of e - Why is e - energy quantized? allowed matter wave forbidden matter wave Any moving object has matter wave properties Fig 8.13

11 What is the de Broglie wavelength (in m) associated with an 90 kg chemistry professor and his bike riding at 15 m/s? Impossibly too small to measure!

Classification of the Elements Fig 8.19 Representative elements Alkali metals Alkaline earth metals Transition metals Halogens Noble gases MetalsNonmetals

13 Chemistry in Action: Discovery of the Noble Gases Sir William Ramsay sun new inactive hidden stranger

14 Physical properties of metals high luster high luster electrical and thermal conductivity electrical and thermal conductivity malleability malleability ductility ductility Physical properties of nonmetals dull appearance dull appearance poor conductors poor conductors brittle brittle

Fig 8.20 Electron dot notation for representative elements Dots represent electrons in outermost shell

Fig 8.21 Location of metals, nonmetals, and semiconductors Metal atoms lose one or more electrons Nonmetal atoms gain one or more electrons

Fig 8.22(A) Metals lose outer electrons Fig 8.22(B) Nonmetals gain outer electrons