Electronegativity and Bonding
How does electronegativity predict the type of bonds atoms form?
Why?
By this point in your academic career, you have probably learned the two most
common types of chemical bonds: ionic bonds and covalent bonds. Ionic bonds
transfer electrons and covalent bonds share them. But what does that really
mean? And how can an atoms electronegativity unit help you understand and
predict the types of chemical bonds that form between atoms.
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Model 1-Electronegativity Values on the Periodic Table
1. What does electronegativity tell you about an element?
a. If an element has a high electronegativity, the element is good at…
b. If an element has a low electronegativity, the element…
2. Do you notice a pattern between metals and non-metals in Model 1?
3. As you move down a group on the periodic table what typically happens to
electronegativity?
a. Which elements did you consider as you were looking for this trend?
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4. As you move from left to right across a period what typically happens to
electronegativity?
a. Which elements did you consider as you were looking for this trend?
5. Which corner of the periodic table are the elements that are the best at
attracting electrons?
6. Which corner of the periodic table are the elements that have difficulty
holding onto to their electrons?
7.
Make a prediction: if two atoms with very different
electronegativities get close together, the atoms are likely to (share
electrons / transfer electrons / bounce off without reacting ). Explain your
reasoning below.
8.
Make a prediction: if two atoms with similar electronegativities get
close together, the atoms are likely to (share electrons / transfer electrons
/ bounce off without reacting ). Explain your reasoning below.
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Model 2 – Using Electronegativity Difference to Determine Bond Type
Bond
Type
Ionic
What’s Holding the
Bonds Together?
Transfer of electrons
Electronegativity
Difference
2 or greater
Example
Cl = 3.16
Na = 0.93
3.16 – 0.93 = 2.23
Covalent Sharing of electrons
Less than 2
O = 3.44
S = 2.58
3.44 – 2.58 = 0.86
Good at attracting
e- in a bond
Has difficulty
attracting e- in a bond
Element Electronegativity
F
3.98
O
3.44
Cl
3.16
N
3.04
Br
2.96
I
2.66
S
2.58
C
2.55
H
2.20
P
2.19
Si
1.90
Cu
1.90
Fe
1.83
Al
1.61
Mg
1.31
Ca
1.00
Li
0.98
Na
0.93
K
0.82
Fr
0.7
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Use Model 2 to determine the types of bonds formed between the
following elements:
9. Fluorine and Potassium
a. Difference in Electronegativity:
b. Type of Bond formed: ionic or covalent
10. Silicon and Oxygen
a. Difference in Electronegativity:
b. Type of Bond formed: ionic or covalent
11. Calcium and Chlorine
a. Difference in Electronegativity:
b. Type of Bond formed: ionic or covalent
12. Aluminum and Chlorine
a. Difference in Electronegativity:
b. Type of Bond formed: ionic or covalent
13. Sodium & Oxygen
a. Difference in Electronegativity:
b. Type of Bond formed: ionic or covalent
14. Look back at your answers to questions 7 & 8. Were your predictions
correct? If not, revise your answers.
15. Use your answers from questions 9-13 to complete the following
statements:
a. Ionic bonds most often form between (metals and non-metals/
non-metals and non-metals/metals and metals)
b. Covalent bonds most often form between (metals and non-metals/
non-metals and non-metals/metals and metals)
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