Chemistry Chapter 6 Flashcards

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Questions and Answers

What are the three main factors of the repulsion theory?

The electron pairs around the central molecule determine its shape

The electron pairs around a central nucleus are trying to repel each other as much as possible

Different numbers of electrons result in different shapes

All of the above (correct)

What shape does 2 electron (bonding) pairs result in?

Linear / planar

What shape does 3 electron (bonding) pairs result in?

Trigonal planar

What shape does 4 electron (bonding) pairs result in?

Tetrahedral Signup and view all the answers

What shape does 5 electron (bonding) pairs result in?

Triangular bipyramidal Signup and view all the answers

What shape does 6 electron (bonding pairs) result in?

Octahedral Signup and view all the answers

What shape does two bonding pairs and two lone pairs result in?

V-shaped / non-linear / bent Signup and view all the answers

What shape does 3 bonding pairs and one lone pair result in?

Tetrahedral Signup and view all the answers

Why do lone pairs of electrons repel more than bonding pairs?

They are slightly closer to the central atom and occupy more space than bonding pairs. Signup and view all the answers

What is the shape of an ammonium ion?

Tetrahedral Signup and view all the answers

What is the shape of carbonate ions?

Trigonal planar Signup and view all the answers

What is the shape of sulfate ions (SO4 2-)?

Tetrahedral Signup and view all the answers

What is the shape of a nitrate ion?

Trigonal planar Signup and view all the answers

Why might a covalent bond experience a stronger attraction from one of the bonded atoms than another?

Because one of the atoms may have more protons than the other. Signup and view all the answers

What is electronegativity?

The ability of an atom to attract the electrons in a covalent bond. Signup and view all the answers

How is electronegativity measured?

On the Pauling electronegativity scale. Signup and view all the answers

Explain how hydrogen fluoride is electronegative.

Fluorine is very electronegative and hydrogen is not, leading to a delta negative charge on fluorine and a delta positive charge on hydrogen. Signup and view all the answers

What are the most electronegative atoms?

Fluorine, chlorine, oxygen, and sulfur. Signup and view all the answers

How can we explain the difference between different bonds?

There is a spectrum of bond types ranging from pure covalent to polar covalent to pure ionic bonds. Signup and view all the answers

What forms a pure covalent bond?

When the two bonded atoms are the same or have a very similar electronegativity. Signup and view all the answers

What forms a polar covalent bond?

When the bonded atoms have a significant difference in electronegativity. Signup and view all the answers

Study Notes

Repulsion Theory

Electron pairs around a central atom dictate molecular shape.
Electron pairs repel each other to maximize distance.
The number of electron pairs influences the resulting shape.

Molecular Shapes Based on Electron Pairs

2 Bonding Pairs:
- Shape: Linear/Planar
- Bond Angle: 180°
3 Bonding Pairs:
- Shape: Trigonal Planar
- Bond Angle: 120°
4 Bonding Pairs:
- Shape: Tetrahedral
- Bond Angle: 109.5°
5 Bonding Pairs:
- Shape: Triangular Bipyramidal
- Bond Angles: 90° and 120°
6 Bonding Pairs:
- Shape: Octahedral
- Bond Angle: 90°

Lone Pairs Effect on Molecular Shape

2 Bonding Pairs & 2 Lone Pairs:
- Shape: V-shaped/Non-linear/Bent
- Bond Angle: 104.5° (due to lone pair repulsion)
3 Bonding Pairs & 1 Lone Pair:
- Shape: Tetrahedral
- Bond Angle: 107°

Lone Pairs and Repulsion

Lone pairs repel more than bonding pairs due to closer proximity to the nucleus and greater spatial occupation.

Shapes of Ions

Ammonium Ion:
- Shape: Tetrahedral
- Bond Angle: 109.5°
Carbonate Ion:
- Shape: Trigonal Planar
- Bond Angle: 120°
- Features: One double-bonded oxygen to carbon.
Sulfate Ion (SO4 2-):
- Shape: Tetrahedral
- Bond Angle: 109.5°
- Structure: 2 double-bonded and 2 single-bonded oxygens.
Nitrate Ion:
- Shape: Trigonal Planar
- Involves a dative covalent bond with one oxygen (-2 charge), a single covalent bond (-1 charge), and a double covalent bond (no charge).

Electronegativity

Defined as the ability of an atom to attract electrons in a covalent bond.
Measured on the Pauling scale, which ranges from 0.4 to 4.0.
Most Electronegative Elements:
- Fluorine (4.0), followed by chlorine, oxygen, and sulfur.

Bonding Differences

Bonds vary in types based on electronegativity differences:
- Pure Covalent: Electronegativity difference = 0
- Polar Covalent: Difference between 0 and 1.8
- Pure Ionic: Difference greater than 1.8
Pure Covalent Bond: Formed between identical or similar electronegativities, resulting in non-polar bonds.
Polar Covalent Bond: Formed when there is a significant electronegativity difference, causing unequal electron sharing.

Example of Electronegativity in Molecules

In hydrogen fluoride, fluorine attracts electrons more strongly than hydrogen, resulting in a partial negative charge on fluorine and a partial positive charge on hydrogen.

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Description

Test your knowledge of Chemistry Chapter 6 with these flashcards focusing on the repulsion theory and molecular shapes. Discover the key principles that determine the geometry of molecules based on electron pairs. Perfect for students looking to reinforce their understanding of molecular structures.