Valence Electrons: TEKS 8.5B
To the teacher:
• This CPO Science PowerPoint presentation is designed to guide you
through the process of presenting the lesson to your students. The
presentation uses a 5-E teaching model: Engage, Explore, Explain,
Elaborate, and Evaluate.
• The PowerPoint Slide notes indicate where you may want to bring in
various lesson elements such as quizzes, readings, investigations,
animations, and practice materials. Additional science background
information is provided in the slide notes where appropriate. You can
view these notes by selecting “View,” then “Normal.” You will see the
notes pane at the bottom of the PowerPoint workspace. Additionally,
the slide notes are available as a separate document, accessible from
the lesson home page.
• The slides that follow are intended for classroom use.
Valence Electrons: TEKS 8.5B
What do aspirin, vinegar, and
plastic wrap have in common?
• Aspirin, vinegar, and plastic wrap are all
compounds made from different
combinations of the same three atoms:
carbon, hydrogen, and oxygen. By
themselves, these atoms cannot reduce pain,
season food, or keep candy clean. But when
these atoms chemically combine in certain
ways to form compounds, they can be used
in may ways.
• In this module, you will learn how and why
atoms combine to form an amazing variety of
materials.
Valence Electrons: TEKS 8.5B
The periodic table
Valence Electrons: TEKS 8.5B
Time to investigate!
• Complete the lesson investigation:
– Chemical Bonds
Valence Electrons: TEKS 8.5B
Identifying elements
• The number of protons in an element
determines that element’s identity.
• The number of protons is called the
element’s atomic number. The atomic
number is listed under the element’s
symbol on the periodic table.
• All helium atoms have two protons, and
all boron atoms have five.
• How many protons does a fluorine
atom have?
Valence Electrons: TEKS 8.5B
Electron arrangements
• A neutral atom has the same number
of electrons and protons.
• The electrons fill the innermost
energy level first. It can hold two
electrons. The second and third
energy levels hold eight electrons
each.
• Look at the electron arrangement for
boron. Notice that the electrons in
the second energy level spread out,
since they repel each other.
• Can you draw the electron arrangement for fluorine?
?
Valence Electrons: TEKS 8.5B
Valence electrons form chemical bonds
• The electrons in the highest
unfilled energy level are called
valence electrons.
• Valence electrons participate in
chemical bonding.
• Elements heavier than boron form
bonds to get eight electrons in their outer shell.
• Elements with five protons or less need to get two
electrons in their outer shell. Hydrogen is a special
case, as it can have zero or two electrons in its outer
shell.
Valence Electrons: TEKS 8.5B
How reactive is an element?
• In science, reactive means that an element readily forms
chemical bonds.
• The closer an element is to having the same number of
valence electrons as a noble gas, the more reactive the
element is.
• Noble gases are not usually reactive because their
valence shells are already filled.
Valence Electrons: TEKS 8.5B
Time for Practice!
• Complete the lesson
practice activity:
– Dot Diagrams
Valence Electrons: TEKS 8.5B
Show what you know!
• Try the lesson’s interactive quiz, or complete a quiz
that your teacher can print out for you.
• Hint:
– You might want to review your lesson reading piece one
more time before trying the quiz.