Summer Research Program for Science Teachers


Fady Ishak 


Legacy High School



August 2004



Electro Negativity





Aim: How and why elements come together?


Objectives: students will:

1- Identify the type of bonding between two atoms of elements given their electro negativity values.

2- Study the trend of electro negativity across the periodic table.


Vocabulary: ( Do now) Define:

      1-electro negativity            

      2- bond strength

      3- polar molecules

      4- non polar molecules

      5- Octet rule



I will perform the following demo to the students and ask them several questions.

Rub a balloon with a piece of wool and bring it close to a thin stream of water.

Write down your in your notebook what did you see and how can you explain it.

Call on some students to give me some answers (no answer is a wrong answer).


Use the analogy of people deciding to buy things together but they agree on different sharing based on different contributions and how this is related to difference in electro negativity leading to different sharing in the compound.



Pivotal question:

Why atoms of elements share?

I will pose this question for the students and look for some answers which should lead to the octet rule concept and the noble gas configuration.

Pivotal question

What controls the formation of bond between atoms?

To find an answer for this question the students will watch a 10 minutes movie about electro negativity and bond formation.

After this there will be a group work regarding the following questions:

1- What is electro negativity? what is its trends across the periodic table?

2- What is bond strength and how does electro negativity affects it?

3- How does electro negativity affect  the type of bond formed?

Students will be called on to share the answer.


Work in groups: Students will work in groups to answer the previous questions and every group will present their answers.


Summary: Students jot down in their notes main ideas of the lesson



1- What is the relation of bond formation and the octet rule? give examples.

2- Describe the pattern of electro negativity across groups and periods of the periodic table.

3- Explain the differences between polar and non polar molecules  by understanding the concept of electron ngativity.



Follow up:

Read about ionic and covalent bonding.



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