Chemistry Chapter 10 Flashcards

Questions and Answers

Which scientist developed a model that can be used to predict the structure of a molecule?

Joseph Proust

John Dalton

Ernest Rutherford

G.N.Lewis (correct)

Which atom has a Lewis structure with an octet?

Ar (correct)

In a Lewis structure, a dash drawn between two atoms represents _______________.

a shared electron pair

Which of the following atoms would most likely be terminal in a Lewis structure?

Hydrogen Signup and view all the answers

Which of the following descriptions best describes the type of electrons used to write a Lewis structure?

Valence Signup and view all the answers

Which of the following is an exception to the octet rule?

SF6 Signup and view all the answers

Which of the following symbols are used to illustrate commonalities between two or more resonance structures?

↔ Signup and view all the answers

How many resonance structures exist for the formate ion, HCO2−?

2 Signup and view all the answers

Which of these molecules or ions exhibit resonance?

O3 and CO32- Signup and view all the answers

Construct an orbital diagram to show the electron configuration for a neutral magnesium atom, Mg.

1s2, 2s2, 2p6, 3s2 Signup and view all the answers

To form a stable ion, will magnesium gain or lose electrons? How many electrons?

Will lose two electrons Signup and view all the answers

Match each ion with the noble gas whose electron configuration it shares.

He = Li+ and Be2+ Ne = O2-, Na+, and N3- Ar = Cl-, Ca2+, and S2- Signup and view all the answers

How many electrons are transferred between the cation and anion to form the ionic bond in one formula unit of each compound?

1 electron: KBr, LiF, and NaCl; 2 electrons: BaS and CaO Signup and view all the answers

Which nonmetals could form an ionic compound with magnesium with the formula MgX2 (where X represents the nonmetal)?

Possible: F, Br, and Cl; Not possible: N, S, and O Signup and view all the answers

Use Lewis theory to determine the formula for the compound that forms from Al and S.

Al2S3 Signup and view all the answers

Use Lewis theory to determine the formula for the compound that forms from Na and S.

Na2S Signup and view all the answers

Use Lewis theory to determine the formula for the compound that forms from Sr and Se.

SrSe Signup and view all the answers

Use Lewis theory to determine the formula for the compound that forms from Ba and F.

BaF2 Signup and view all the answers

Use the Lewis model to predict the correct formula for the compound that forms between Ca and Br.

CaBr2 Signup and view all the answers

How many total valence electrons are in the Lewis structure of NO3−?

24 Signup and view all the answers

Determine the electron geometry of N2O (oxygen is terminal).

Linear Signup and view all the answers

Determine the molecular geometry of N2O (oxygen is terminal).

Linear Signup and view all the answers

Determine the electron geometry of SO2.

Trigonal planar Signup and view all the answers

Determine the molecular geometry of SO2.

Bent Signup and view all the answers

Determine the electron geometry of H2S.

Tetrahedral Signup and view all the answers

Determine the molecular geometry of H2S.

Bent Signup and view all the answers

Determine the electron geometry of PF3.

Tetrahedral Signup and view all the answers

Determine the molecular geometry of PF3.

Trigonal pyramidal Signup and view all the answers

CO2−3

Trigonal planar Signup and view all the answers

ClO−2

Bent Signup and view all the answers

NO−3

Trigonal planar Signup and view all the answers

NH+4

Tetrahedral Signup and view all the answers

What is the molecular geometry of N2O (Nitrogen is the central atom)?

Linear Signup and view all the answers

What is the molecular geometry of PBr3?

Trigonal pyramidal Signup and view all the answers

Which bond is polar?

A bond between H and Cl Signup and view all the answers

Which molecule is polar?

SCl2 Signup and view all the answers

If a molecule has polar bonds, is the molecule itself polar?

If a molecule has polar bonds, the molecule can be either polar or nonpolar. Signup and view all the answers

Why?

The two requirements of a polar molecule are: the molecule must have polar bonds and the polar bonds must be distributed asymmetrically, otherwise they cancel out. Signup and view all the answers

How do you determine the number of electrons that go into the Lewis structure of a molecule?

Add up the valence electrons from each atom that is forming the molecule. Signup and view all the answers

What happens if you try to mix a polar liquid with a nonpolar one?

They will separate to form two distinct regions. Signup and view all the answers

Use the Lewis model to explain why the compound that forms between hydrogen and sulfur has the formula H2S.

Each H atom in a compound can contribute 1 valence e−, a S atom contributes 6 valence e−. When H2S forms, each H atom shares their 1e− with S and in doing so has achieved a stable duet. Signup and view all the answers

Would you expect HS to be stable?

False Signup and view all the answers

Would you expect H3S to be stable?

False Signup and view all the answers

If all of the electron groups around a central atom are bonding groups (that is, there are no lone pairs), what is the molecular geometry for two electron groups?

Linear Signup and view all the answers

If all of the electron groups around a central atom are bonding groups (that is, there are no lone pairs), what is the molecular geometry for three electron groups?

Trigonal planar Signup and view all the answers

If all of the electron groups around a central atom are bonding groups (that is, there are no lone pairs), what is the molecular geometry for four electron groups?

Tetrahedral Signup and view all the answers

Indicate which of the electrons in the electron configuration are shown in the Lewis structure.

1s22s22p63s23p64s23d104p65s1−−− Signup and view all the answers

Indicate which of the electrons in the electron configuration are shown in the Lewis structure.

1s22s22p63s23p64s23d104p6−−− Signup and view all the answers

Electron groups: 2. Bonding groups: 2. Lone pairs: 0.

Angle: 180 Signup and view all the answers

Bonding groups: 3. Lone pairs: 0.

Electron geometry: Trigonal planar Signup and view all the answers

Bonding groups: 2. Lone pairs: 1.

Electron geometry: Trigonal planar Signup and view all the answers

Bonding groups: 4. Lone pairs: 0.

Angle: 109.5 Signup and view all the answers

Bonding groups: 3. Lone pairs: 1.

Molecular: Trigonal pyramidal Signup and view all the answers

Bonding groups: 2. Lone pairs: 2.

Molecular: Bent Signup and view all the answers

How many bonding electrons are in the Lewis structure of N2?

6 Signup and view all the answers

How many bonding electrons are in the Lewis structure of carbon monoxide, CO?

6 Signup and view all the answers

How many valence electrons are in the nitrate ion?

24 Signup and view all the answers

The correct Lewis structure for BF3 would be exactly:

no double bonds Signup and view all the answers

Which of the following compounds have resonance structures?

O3 Signup and view all the answers

The VSEPR theory predicts that the angle between the central carbon atom and the two oxygen atoms in CO2 measures 180°.

True Signup and view all the answers

What is the angle between electron groups in the linear electron geometry?

180 Signup and view all the answers

When you have 4 electron groups and none of them are lone pairs, the molecular geometry is trigonal pyramidal.

False Signup and view all the answers

What is the molecular geometry if you have 4 single bonds around the central atom?

tetrahedral Signup and view all the answers

What is the electron geometry if you have 3 electron groups around the center atom?

trigonal planar Signup and view all the answers

What is the molecular geometry of CCl4?

tetrahedral Signup and view all the answers

The electron geometry and the molecular geometry of ammonia (NH3) are, respectively:

tetrahedral, trigonal pyramidal Signup and view all the answers

The elements with the highest electronegativity values tend to be found in the:

upper right-side of the periodic table. Signup and view all the answers

Which molecule listed below has a polar covalent bond?

H2O Signup and view all the answers

Which molecule listed below has a nonpolar covalent bond?

H2 Signup and view all the answers

Which molecule listed below is a polar molecule?

HCN, NH3, and H2O Signup and view all the answers

Which of the following statements are TRUE about the BF3 molecule?

BF3 has a trigonal planar molecular geometry. BF3 is nonpolar. BF3 violates the octet rule for the central atom. Signup and view all the answers

Consider the following electronegativity values: H = 2.1, Cl = 3.0, F = 4.0. Which molecule below would you expect to have the more polar bond?

HF Signup and view all the answers

The electronegativity value for Mg is 1.2 and the value for O is 3.5. Based on these values, what type of bond is expected for a compound formed between Mg and O?

ionic Signup and view all the answers

Electronegativity Difference

2.0 + Signup and view all the answers

CBr4

tetrahedral Signup and view all the answers

H2CO

trigonal planar Signup and view all the answers

CS2

linear Signup and view all the answers

BH3

trigonal planar Signup and view all the answers

Study Notes

G.N. Lewis and Lewis Structures

G.N. Lewis developed a model for predicting molecular structures.
Lewis structures use symbols to represent atoms, with dots for valence electrons.
A dash between atoms indicates a shared electron pair.

Valence Electrons and Octet Rule

Valence electrons are the electrons involved in chemical bonding.
Noble gases typically have a complete octet, contributing to their stability (e.g., Ar has an octet).
Exceptions to the octet rule include molecules like SF6.

Resonance Structures

Resonance occurs when more than one valid Lewis structure can be drawn for a molecule.
The symbol ↔ illustrates shared characteristics between multiple resonance structures.
The formate ion (HCO2−) has 2 resonance structures.

Electron and Molecular Geometry

Electron geometry considers bonding and lone pairs around a central atom.
For two electron groups: linear geometry (180° angle).
For three electron groups: trigonal planar geometry (120° angle).
For four electron groups: tetrahedral geometry (109.5° angle).

Bonding and Ions

Ionic compounds form from the transfer of electrons between metals and nonmetals.
Magnesium typically loses two electrons to form a stable ion.
Common ionic compounds include Na2S and BaF2.
Elements with high electronegativity often form polar bonds, as seen in H2O and HF.

Polar vs. Nonpolar Molecules

Polar molecules have an uneven distribution of charge due to their molecular structure and bonds.
Nonpolar molecules, like H2, have an even charge distribution.
Geometry plays a crucial role in determining whether a molecule is polar or nonpolar.

Molecular Shapes

Molecular geometry determines physical properties and reactivity.
Examples of molecular geometries include:
- NH3: Trigonal pyramidal
- H2S: Bent
- CO2: Linear
- CF4: Tetrahedral

Electronegativity and Bonding Types

Electronegativity differences determine bond types:
- Pure covalent (0-0.4), polar covalent (0.4-2.0), and ionic (2.0+).
Compounds formed from Mg and O are expected to be ionic due to their significant electronegativity difference.

Summary of Notable Compounds

Ozone (O3) exhibits resonance structures.
BF3 is nonpolar with trigonal planar geometry and violates the octet rule.
The molecule HCN and others like NH3 and H2O are polar due to their structure and electronegativity differences.

Important Concepts in Lewis Structures

When counting electrons for Lewis structures, sum the valence electrons from all atoms involved.
Mixing polar and nonpolar liquids results in separation into distinct regions rather than forming a homogenous solution.
Stable compounds can form despite differing electron configurations, emphasizing understanding of valence electrons and molecular geometries.

VSEPR Theory

VSEPR (Valence Shell Electron Pair Repulsion) theory predicts molecular shapes based on repulsion between electron groups.
Molecules with no lone pairs around a central atom exhibit clear geometric arrangements (linear, trigonal planar, tetrahedral).

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Test your knowledge on Lewis structures and molecular predictions with these flashcards from Chemistry Chapter 10. Each card will challenge you with questions about notable scientists and atomic structures. Perfect for revision and reinforcing your understanding.