http://www.ck12.orgCHAPTER
5 Electrons in Atoms
Chapter Outline
5.1 Properties of Light
5.2 THEBOHR ANDQUANTUMMECHANICALMODELS OF THEATOM
5.3 ELECTRONARRANGEMENT INATOMS
5.4 REFERENCES
Light has always intrigued humans. Whether it was the light from the sun or the light from a fire, we have used
light and made light when none was naturally available. The interaction of light with different materials has long
been studied. Research by scientists in the late nineteenth century led to an intriguing discovery. Light, under
the right conditions, creates a small voltage (ejects electrons) when shined on certain metals. Einstein eventually
explained this photoelectric effect, adding to our essential understanding of the nature of light. This discovery
formed the foundation for a technology which later became known as photovoltaic cells. Photovoltaic cells are the
materials found in the solar panels shown in the figure above. The solar panels shown here can generate enough
electricity throughout the day to power 5 average American homes (assuming an average monthly energy use
of about ~1000 kWh). Photovoltaic cells have become quite affordable and are now a reasonable alternative for
electricity generation.
Image co pyright anweber, 2014 .www.shutterstock.com.U sed under license f rom Shutterstock.com.