http://www.ck12.org Chapter 2. Matter
FIGURE 2.85
- Electrons are always added to the lowest energy level first until it has the maximum number of electrons
possible, and then electrons are added to the next higher energy level until that level is full, and so on. The
maximum number of electrons at a given energy level depends on its number of orbitals. There are at most
two electrons per orbital. - Electrons in the outermost energy level of an atom are called valence electrons. They determine many of the
properties of an atom, including how reactive it is.
Vocabulary
- energy level: Area located at a fixed distance from the nucleus of an atom where electrons can orbit the
nucleus.
Explore More
Watch the video about electrons at the following URL, and then answer the questions below.
http://www.ehow.com/video_5234848electrons.html
MEDIA
Click image to the left for use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/117721- How many energy levels exist in atoms?
- What is the maximum possible number of electrons at the fifth energy level?
- Assume an energy level can hold a maximum of 98 electrons. Which energy level is it? How many orbitals
does this energy level have?
Review
- What are energy levels?
- Relate energy levels to the amount of energy their electrons have.