Ch.10 - Molecular Shapes & Valence Bond TheoryWorksheetSee all chapters
All Chapters
Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
Ch.8 - Periodic Properties of the Elements
Ch.9 - Bonding & Molecular Structure
Ch.10 - Molecular Shapes & Valence Bond Theory
Ch.11 - Liquids, Solids & Intermolecular Forces
Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch. 17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds
Jules Bruno

Electronegativity

Electronegativity can be thought of as the tendency of an atom to attract electrons. If we take a look at any basic periodic table, realize that the trend for electronegativity is, as we move from left to right, electronegativity will increase. As we move up any group, it will also increase. 

Electronegativity periodic table

Based on this, we’re going to say that fluorine is the most electronegative element on the periodic table with a value of 4.0. We don’t include noble gasses in terms of electronegativity because they already have the perfect number of electrons in their outer shell so they’re not included in this. 

Electronegativity trends

We’re going to say that Francium which is on the very far left into the bottom of Group 1A, it has the lowest electronegative value of 0.7. You’re not going to be expected to memorize all of these electronegative values but it’s important that you remember the trend in terms of them. Fluorine is the most electronegative. As we head towards it, electronegativity increases. Also, realize that oxygen would have the second highest electronegative value followed by chlorine. 

Polarity and electronegativity

What’s important about electronegativity is that it can help us with bond polarity. Two elements connected together, from this we can determine what kind of bond we have. 

The different definitions for them are if there’s a difference of zero for electronegative values, we’d say that that bond is classified as a pure covalent bond. 

For example, here we have Br2. In it, we have two bromines connected to each other. They both have values of 2.8 so if you subtracted them from each other, that would give us our electronegative difference. Basically a pure covalent bond is when you have identical elements connected to one another.

From there, if the electronegative difference is small, meaning it’s from 0.1 to 0.4, we classify it as a nonpolar covalent bond. Great example of this is when you have a carbon single bonded to a hydrogen. Carbon here is 2.5, hydrogen here is 2.1. Depending on the addition that you have, you might see it as 2.1 or 2.2. Either case, it really doesn't matter because it falls within this range. You do the larger electronegative value minus the smaller one and that would give you your difference. 

Then you can see that if you have a difference between 0.5 and 1.7, that would be classified as a polar covalent bond. Remember, as we say covalent, covalent just means nonmetals connected together. We go into ionic when the difference between the two elements is greater than 1.7. Ionic is technically just a positive ion which tends to be a metal connected to a negative ion which tends to be a nonmetal. 

Summary 

So remember, electronegativity just tells us the likelihood of an atom attracting electrons towards it. The bigger the difference between two elements and their electronegative values, then the more polar their bond becomes and therefore the more reactive it’ll be later. It’s important to just remember the general trends and then just remember the four different classifications for the types of bond that result from differences in electronegativity. If you’re still having issues in terms of this concept, make sure you go back and take a look at my chapter videos dealing with the whole idea of electronegativity as well as the forces between two elements forming a bond with one another. 


Jules Bruno

Jules felt a void in his life after his English degree from Duke, so he started tutoring in 2007 and got a B.S. in Chemistry from FIU. He’s exceptionally skilled at making concepts dead simple and helping students in covalent bonds of knowledge.


Additional Problems
For the elements Rb, F and O, the order of increasing electronegativity is A) Rb < F < O B) Rb < O < F C) O < F < Rb D) F < Rb < O
Which element is more electronegative than arsenic and less electronegative than sulfur? a) chlorine b) phosphorus c) tin d) oxygen 
Place the following elements in order of decreasing electronegativity                          S       Cl      Se a. Cl > S > Se b. Se > S >Cl c. Cl > Se > S d. Se > Cl > S e. S > Cl > Se 
Which of the following has the bonds ranked in order of increasing ionic character? 1. Cl−Cl < Si−Cl < Br−Cl < Mg−Br < Rb−Cl 2. Mg−Br < Rb−Cl < Si−Cl < Br−Cl < Cl−Cl 3. Cl−Cl < Br−Cl < Si−Cl < Rb−Cl < Mg−Br 4. Cl−Cl < Br−Cl < Si−Cl < Mg−Br < Rb−Cl
A major challenge in implementing the “hydrogen economy” is finding a safe, lightweight, and compact way of storing hydrogen for use as a fuel. The hydrides of light metals are attractive for hydrogen storage because they can store a high weight percentage of hydrogen in a small volume. For example NaAlH4, can release 5.6% of its mass as H2 upon decomposing to NaH(s), Al(s), and H2(g). NaAlH4 possesses both covalent bonds, which hold polyatomic anions together, and ionic bonds.Which element in NaAlH4 is the most electronegative?
By referring only to the periodic table, select the most electronegative element in group 6A.
By referring only to the periodic table, select the least electronegative element in the group Al, Si, P.
By referring only to the periodic table, select the most electronegative element in the group Ga, P, Cl, Na.
Using only the periodic table as your guide, select the most electronegative atom in each of the following sets.Na, Mg, K, Ca.
Using only the periodic table as your guide, select the most electronegative atom in each of the following sets.P, S, As, Se.
Using only the periodic table as your guide, select the most electronegative atom in each of the following sets.Be, B, C, Si.
Using only the periodic table as your guide, select the most electronegative atom in each of the following sets.Zn, Ge, Ga , As.
How do electronegativity values generally vary going down a column in the periodic table?
What is electronegativity?
In general, as you go across a period in the periodic table from left to right, the atomic radius________________; the electronegativity ______________ and the first ionization energy________________.A) decreases, decreases, increasesB) increases, increases, decreasesC) increases, increases, increasesD) decreases, increases, increasesE) decreases, increases, decreases
Which of the following statement is  true?The electronegativity of an atom is defined as electron affinity of the atom.The electronegativity of an atom depends only on the value of the ionization energy of the atom.Atoms with high ionization energies and high electron affinities have low electronegativites.Atoms with low ionization energies and low electron affinities have low electronegativites.Atoms with low ionization energies and low electron affinities have high electronegativities. 
Arrange the following elements in order of decreasing electronegativity.Rank from most to least electronegative. To rank items as equivalent, overlap them.Oxygen, Potassium, Cobalt, Selenium
Rank these elements according to electronegativity (highest to lowest).K, Rb, F, Ga, C
Explain the following observations: (b) HF is called a weak acid, and yet it is very reactive
Place the following elements in order of decreasing electronegativityS Cl Sea. Cl > S > Seb. Se > S > Clc. Cl > Se > Sd. Se > Cl > Se. S > Cl > Se 
In a polar covalent bond,  ______.A. electrons are shared equallyB. electrons are shared unequallyC. electrons are transferred
Generally speaking, in the periodic table, electronegativity (decreases, increases) when moving from left to right and (decreases, increases) when moving from top to bottom of the periodic table.a. decreases, increasesb. increases, decreasesc. increases, increasesd. decreases, decreases
Which of the following is a correct definition for electronegativity? A) The relative negative charge of an atom B) The ability of an atom in a covalent bond to pull electrons C) The attraction between an atom and an electron D) The work needed to remove an electron from an atom E) The extent a covalent bond is considered polar
One scale for electronegativity is based on the concept that the electronegativity of any atom is proportional to the ionization energy of the atom minus its electron affinity: electronegativity = k(I–EA), where k is a proportionality constant.How does this definition explain why the electronegativity of F is greater than that of Cl even though Cl has the greater electron affinity?
From its position in the periodic table, determine which atom in the pair is more electronegative: Br or Cl.
From its position in the periodic table, determine which atom in the pair is more electronegative: N or O.
From its position in the periodic table, determine which atom in the pair is more electronegative: S or O.
From its position in the periodic table, determine which atom in the pair is more electronegative: P or S.
From its position in the periodic table, determine which atom in the pair is more electronegative: Si or N.
From its position in the periodic table, determine which atom in the pair is more electronegative: Ba or P.
From its position in the periodic table, determine which atom in the pair is more electronegative: N or K.
From its position in the periodic table, determine which atom in the pair is more electronegative: N or P.
From its position in the periodic table, determine which atom in the pair is more electronegative: N or Ge.
Without using Fig. 3‑4, predict the order of increasing electronegativity in the following group of element.a. C, N, O
From its position in the periodic table, determine which atom in the pair is more electronegative: S or F.
Without using Fig. 3‑4, predict the order of increasing electronegativity in the following group of element.b. S, Se, Cl
From its position in the periodic table, determine which atom in the pair is more electronegative: Cl or S.
Without using Fig. 3‑4, predict the order of increasing electronegativity in the following group of element.c. Si, Ge, Sn
Without using Fig. 3‑4, predict the order of increasing electronegativity in the following group of element.d. Tl, S, Ge
From its position in the periodic table, determine which atom in the pair is more electronegative: H or C.
Without using Fig. 3‑4, predict the order of increasing electronegativity in the following group of element.a. Na, K, Rb
From its position in the periodic table, determine which atom in the pair is more electronegative: Se or P.
Which set of elements is arranged in order of increasing electronegativity?a) O < S < As < Geb) Ge < As < S < Oc) S < O < As < Ged) As < O < Ge < S
Without using Fig. 3‑4, predict the order of increasing electronegativity in the following group of element.b. B, O, Ga
From its position in the periodic table, determine which atom in the pair is more electronegative: C or Si.
From their positions in the periodic table, arrange the atoms in the following series in order of increasing electronegativity: C, F, H, N, O.
Without using Fig. 3‑4, predict the order of increasing electronegativity in the following group of element.c. F, Cl, Br
From their positions in the periodic table, arrange the atoms in the following series in order of increasing electronegativity: Br, Cl, F, H, I.
Without using Fig. 3‑4, predict the order of increasing electronegativity in the following group of element.d. S, O, F
From their positions in the periodic table, arrange the atoms in the following series in order of increasing electronegativity: F, H, O, P, S.
From their positions in the periodic table, arrange the atoms in the following series in order of increasing electronegativity: Al, H, Na, O, P.
From their positions in the periodic table, arrange the atoms in the following series in order of increasing electronegativity: Ba, H, N, O, As.
From their positions in the periodic table, arrange the atoms in the following series in order of increasing electronegativity: As, H, N, P, Sb.
From their positions in the periodic table, arrange the atoms in the following series in order of increasing electronegativity: Cl, H, P, S, Si.
From their positions in the periodic table, arrange the atoms in the following series in order of increasing electronegativity: Br, Cl, Ge, H, Sr.
From their positions in the periodic table, arrange the atoms in the following series in order of increasing electronegativity: Ca, H, K, N, Si.
From their positions in the periodic table, arrange the atoms in the following series in order of increasing electronegativity: Cl, Cs, Ge, H, Sr.
Exercise 31. Without using Fig. 3‑4, predict the order of increasing electronegativity in each of the following groups of elements.a. C, N, Ob. S, Se, Clc. Si, Ge, Snd. Tl, S, GeExercise 33. Without using Fig. 3‑4, predict which bond in each of the following groups will be the most polar.a. C—F, Si—F, Ge—Fb. P—Cl or S—Clc. S—F, S—Cl, S—Brd. Ti—Cl, Si—Cl, Ge—ClRepeat Exercises 31 and 33, this time using the values for the electronegativities of the elements given in figure below. Are there differences in your answers?
Exercise 32. Without using Fig. 3‑4, predict the order of increasing electronegativity in each of the following groups of elements.a. Na, K, Rbb. S, Se, Clc. Si, Ge, Snd. Tl, S, GeExercise 34. Without using Fig. 3‑4, predict which bond in each of the following groups will be the most polar.a. C—H, Si—H, Sn—Hb. Al—Br, Ga—Br, In—Br, Tl—Brc. C—O or Si—Od. O—F or O—ClRepeat Exercises 32 and 34, this time using the values for the electronegativities of the elements given in figure below. Are there differences in your answers?
You may want to reference (Pages 310 - 315) Section 8.4 while completing this problem.Indicate the more electronegative atom in each pair: (a) B–F, (b) Cl–Cl, (c) Se–O, (d) H–I.
Using the periodic table only, arrange the elements in following set in order of increasing EN:(a) S, O, Si
Using the periodic table only, arrange the elements in following set in order of increasing EN:(b) Mg, P, As
Using the periodic table only, arrange the elements in following set in order of increasing EN:(a) I, Br, N
Using the periodic table only, arrange the elements in following set in order of increasing EN:(b) Ca, H, F
Using the periodic table only, arrange the elements in following set in order of decreasing EN:(a) N, P, Si
Using the periodic table only, arrange the elements in following set in order of decreasing EN:(b) Ca, Ga, As
Arrange these elements in order of decreasing electronegativity: P, Na, N, Al.
Using the periodic table only, arrange the elements in the following set in order of decreasing EN:(a) Br, Cl, P
Using the periodic table only, arrange the elements in the following set in order of decreasing EN:(b) I, F, O
Use the simulation (http://openstaxcollege.org/l/16MolecPolarity) to perform the following exercises for a real molecule. You may need to rotate the molecules in three dimensions to see certain dipoles.(b) Look at the bond dipoles for NH3. Use these dipoles to predict whether N or H is more electronegative.
Rank the members of the following set of compounds in order of decreasing ionic character of their bonds. Use partial charges to indicate the bond polarity of each:(a) PCl3, PBr3, PF3
For the group 6A elements, what is the trend in electronegativity with increasing atomic number?
Which of the following statements about electronegativity is false?(a) Electronegativity is the ability of an atom in a molecule to attract electron density toward itself.(b) Electronegativity is the same thing as electron affinity.(c) The numerical values for electronegativity have no units.(d) Fluorine is the most electronegative element.(e) Cesium is the least electronegative element.
Electronegativity is a measure of ___________________. a. the magnitude of the negative charge on an electron b. the energy released when an electron is added to an atom c. the attraction by an atom for electrons in a chemical bond d. the magnitude of the negative charge on a molecule e. the energy needed to remove an electron from an atom
True or false: The most easily ionizable elements are the most electronegative.
When the electron cloud of a molecule is easily distorted, the molecule has a high _____________.(A) polarity (B) polarizability (C) dipole moment (D) van der Waals radius
Arrange the following molecules in order of increasing dipole moment: H2O, H2S, H2Te, H2Se
A major challenge in implementing the “hydrogen economy” is finding a safe, lightweight, and compact way of storing hydrogen for use as a fuel. The hydrides of light metals are attractive for hydrogen storage because they can store a high weight percentage of hydrogen in a small volume. For example NaAlH4, can release 5.6% of its mass as H2 upon decomposing to NaH(s), Al(s), and H2(g). NaAlH4 possesses both covalent bonds, which hold polyatomic anions together, and ionic bonds.Which element in NaAlH4 is the least electronegative?
Which of these elements has the highest electronegativity?a) lithiumb) cesiumc) iodined) oxygen
List the elements Ca, Si, and K in order of  increasing electronegativity. a) Ca < K < Sib) K < Si < Cac) Si < Ca < Kd) K < Ca < Si
Of the atoms below, __________ is the most electronegative.A) SiB) ClC) RbD) CaE) S
A probe sent to the planet Mercury has measured the electronegativities of several elements it has detected on the planet. Element:                       1                2            3            4            5Electronegativity:          3.04          1.31        2.04       2.20       2.66Which element would you expect to identify as a metal?a. Element 1b. Element 2c. Element 3d. Element 4e. Element 5
Which of the following is false concerning electronegativity?A. Fluorine is the most electronegative atomB. Electronegativity can be measured by observing individual atoms in the gas phaseC. Electronegativity affects covalent bondsD. All electronegativity scales are relativeE. Larger atoms generally have lower electronegativities than smaller atoms
Arrange these elements according to electronegativity.  Rb    F    Al    N    Na
A carbon-hydrogen bond in ethane (CH3CH3) is best described as 
In the compound sodium methoxide (NaOCH3), there is ___ bonding
Which of these is a polar covalent bond?
Using only a periodic table as a guide, arrange the following atoms in order of decreasing electronegativity.  Na   O   F   Si   S