Atoms and the Periodic Table Chapter 8. Visible light consists of electromagnetic waves Electromagnetic radiation: emission and transmission of energy.

Atoms and the Periodic Atoms and the Periodic TableTable

Chapter 8Chapter 8

Visible light consists of electromagnetic waves

Electromagnetic radiation: emission and transmission of energy in the form of electromagnetic waves.

Speed of light (c) in vacuum = 3.00 x 108 m/s

Fig. 7.2

Fig. 7.3 The Electromagnetic Spectrum

White light is separated into its color

components by a prism

White light is separated into its color

components by a diffraction grating

The tracks of a compact disc act as a diffraction grating,producing a separation of the colors of white light.

Line Emission Spectrum of Hydrogen Atoms

Fig 8.8 (A) Continuous spectrum (B) Line spectrum

Fig 8.9 Three series in the H atom line spectrum

First recorded emission spectrum of the sun (1817)

intensity

wavelength

1. e− can only have specific (quantized) energy values

2. e− in an orbit does not emit radiant energy

3. Light is emitted as e- moves from a higher orbit to a lower orbit

4. Light must be absorbed to move an e− from a lower to a higher orbit

Bohr’s Model of the Atom (1913)

Fig 8.10

e-

Fig 8.11 Energy level diagram for the H atom

Ephoton = EH - EL

E = hf

E = hf

Low energyHigh energy

Egreen > Ered

The bigger the jump,the bluer the photon

Electron configurations of some atoms

Valence electrons ≡ electrons in outermost shell

Fig 8.18 Electron dot notation for representative elements1A

2A 3A

8A

4A 5A 6A 7A

Elements are arranged in order of increasing atomic number

Metals

• good conductors of heat and electricity

• shiny, ductile, malleable

• all solids with one exception

Nonmetals

• poor conductors

• dull appearance, brittle

• consist of solids, liquids, and gases

Physical Properties of the ElementsPhysical Properties of the Elements

Period

Group

Alkali M

etal

Noble G

as

Halogen

Alkali E

arth Metal

p 237

Chemistry In ActionNatural abundance of elements in Earth’s crust

Natural abundance of elements in human body