Chemical Bonding and Structure
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Questions and Answers

What is the definition of a chemical bond?

A stable association between atoms, formed as a result of the combination of atoms.

The majority of different substances that we encounter in our daily lives are formed from only 100 chemically different types of atoms.

True (A)

What are the main types of chemical bonds discussed in this chapter?

ionic, covalent, metallic

The metallic bond is formed by attractions between oppositely charged particles.

<p>True (A)</p> Signup and view all the answers

What is the definition of an ion?

<p>An ion is a charged particle formed by the loss or gain of one or more electrons by atoms or groups of atoms.</p> Signup and view all the answers

Elements that have a small number of electrons in their outer shells are called ______ which lose electrons to form positively charged ions called ______.

<p>metals, cations</p> Signup and view all the answers

Elements that have a large number of electrons in their outer shells are called ______, and they gain electrons to form negatively charged ions called ______ .

<p>non-metals, anions</p> Signup and view all the answers

Match the following elements with the type of ion they form:

<p>sodium = cation sulfur = anion aluminium = cation bromine = anion phosphorus = anion oxygen = anion calcium = cation carbon = generally does not form ions nitrogen = anion potassium = cation</p> Signup and view all the answers

What does the Octet rule state?

<p>Atoms tend to achieve a stable electron arrangement with eight electrons in their outer shell to form a complete outer shell like that of a noble gas.</p> Signup and view all the answers

What are some examples of polyatomic ions?

<p>Examples of polyatomic ions include NH4+, OH-, NO3-, HCO3-, CO32-, SO42-, and PO43-.</p> Signup and view all the answers

Ionic bonds are formed by electrostatic attractions between oppositely charged ______ .

<p>ions</p> Signup and view all the answers

How can we determine the charge of a particular metal ion?

<p>We can determine the charge of a particular metal ion by looking at its position in the Periodic Table.</p> Signup and view all the answers

What is the formula unit for a compound?

<p>A formula unit is the simplest ratio of ions present in an ionic compound.</p> Signup and view all the answers

What is an ionic lattice?

<p>A three-dimensional arrangement of ions in a compound, held together by electrostatic forces.</p> Signup and view all the answers

The term coordination number refers to the number of electrons around a particular ion in an ionic lattice.

<p>False (B)</p> Signup and view all the answers

What are the three main types of intermolecular forces?

<p>London dispersion forces, dipole-dipole forces, and hydrogen bonds</p> Signup and view all the answers

London dispersion forces can only occur between non-polar molecules.

<p>True (A)</p> Signup and view all the answers

How does the strength of London dispersion forces vary?

<p>The strength of London dispersion forces increases with increasing molecular size.</p> Signup and view all the answers

Why do non-polar molecules generally have low melting and boiling points?

<p>Because it takes less energy to overcome weak London dispersion forces to separate the molecules.</p> Signup and view all the answers

Dipole-dipole forces are stronger than London dispersion forces.

<p>True (A)</p> Signup and view all the answers

What is the definition of a hydrogen bond?

<p>A particularly strong type of dipole-dipole interaction that occurs when a hydrogen atom is covalently bonded to a very electronegative atom, such as fluorine, nitrogen, or oxygen.</p> Signup and view all the answers

The umbrella term van der Waals' forces includes dipole-dipole and London dispersion forces.

<p>True (A)</p> Signup and view all the answers

Van der Waals' forces can be intramolecular forces.

<p>True (A)</p> Signup and view all the answers

Non-polar substances are more soluble in polar solvents.

<p>False (B)</p> Signup and view all the answers

What property of a compound is defined as the tendency for it to vaporize?

<p>Volatility.</p> Signup and view all the answers

The melting point of a substance is solely determined by the strength of its intermolecular forces.

<p>False (B)</p> Signup and view all the answers

Giant covalent structures are the largest types of covalent structures and are known as macromolecules.

<p>True (A)</p> Signup and view all the answers

What are allotropes?

<p>Different forms of the same element that exist in the same physical state.</p> Signup and view all the answers

Metals are good electrical conductors because their electrons are delocalized.

<p>True (A)</p> Signup and view all the answers

The strength of metallic bonding is independent of the size of the cation.

<p>False (B)</p> Signup and view all the answers

What is the definition of a sigma bond?

<p>A sigma bond is formed by the direct head-on/end-to-end overlap of atomic orbitals, resulting in electron density concentrated between the nuclei of the bonding atoms.</p> Signup and view all the answers

What is hybridization?

<p>Hybridization is the process where atomic orbitals within an atom mix to form new hybrid atomic orbitals of intermediate energy.</p> Signup and view all the answers

Match the following types of hybridization with the number of sigma bonds that they form and their bond angle:

<p>sp3 = 4 sigma bonds, 109.5° sp2 = 3 sigma bonds, 120° sp = 2 sigma bonds, 180°</p> Signup and view all the answers

What is resonance?

<p>A concept that accounts for the delocalisation of electrons between more than one possible bonding position within a molecule or ion, resulting in bonds with intermediate bond lengths and strengths between single and double bonds.</p> Signup and view all the answers

Formal charge is a useful tool for determining the relative stability of different Lewis structures.

<p>True (A)</p> Signup and view all the answers

In general, the lower the formal charge on an atom, the more stable the Lewis structure.

<p>True (A)</p> Signup and view all the answers

What is a free radical?

<p>A free radical is a reactive species, which contains an unpaired electron in its outer shell.</p> Signup and view all the answers

What is the main function of the ozone layer?

<p>To absorb harmful UV radiation from the sun.</p> Signup and view all the answers

Why does the ozone layer become thinner?

<p>Human activity is the main cause of ozone depletion. The release of chemicals, such as CFCs and nitrogen oxides, leads to the catalytic destruction of ozone in the stratosphere.</p> Signup and view all the answers

What does VSEPR theory stand for?

<p>Valence Shell Electron Pair Repulsion theory.</p> Signup and view all the answers

The shape of a molecule is determined by the position of all the electron pairs.

<p>False (B)</p> Signup and view all the answers

The stronger the intermolecular forces are, the higher the melting and boiling points of a substance.

<p>True (A)</p> Signup and view all the answers

Giant covalent structures have high melting and boiling points because they contain weak intermolecular forces.

<p>False (B)</p> Signup and view all the answers

The physical properties of covalent compounds are a result of intermolecular forces.

<p>True (A)</p> Signup and view all the answers

Ionic compounds generally have higher melting and boiling points than covalent compounds.

<p>True (A)</p> Signup and view all the answers

What is required to break the bonds in a substance and cause it to melt?

<p>The intermolecular forces must be overcome for a substance to melt.</p> Signup and view all the answers

Study Notes

Chemical Bonding and Structure

  • Ionic compounds: Consist of ions held together in lattice structures by ionic bonds.
  • Covalent compounds: Form by sharing electrons.
  • Lewis structures: Show electron domains in the valence shell, used to predict molecular shape.
  • Molecular properties: Result from forces between their molecules.
  • Metallic bonds: Involve a lattice of cations with delocalized electrons.
  • Bonding systems: Often require sophisticated concepts and theories.
  • Hybridization: Results from mixing atomic orbitals to form hybrid orbitals with equivalent energy.
  • Chemical bonds: How atoms combine to form stable associations.
  • Ionic bonds form: When electrons are transferred between atoms.
  • Ionic compounds: Usually solids with lattice structures and are electrically conductive in molten or aqueous forms.
  • Metals form cations: By losing valence electrons
  • Non-metals form anions: By gaining electrons
  • Electron configurations: Determine the number of electrons lost or gained during reactions.

Ionic bonding and structure

  • Ions: Charged particles formed by loss or gain of electrons.
  • Ionic bond: Electrostatic attraction between oppositely charged ions.
  • Ionic compounds properties:
    • Mostly solids
    • High melting and boiling points.
    • Often soluble in water
    • Conduct electricity when molten or dissolved.
  • Polyatomic ions: Groups of atoms acting as a single ion (e.g., (NH_4^+), (OH^-), (NO_3^-), (HCO_3^-), (CO_3^{2-}), (SO_4^{2-}), (PO_4^{3-})).
  • Predicting ionic charge: Determined by the number of electrons lost or gained from the group number on the Periodic Table.

Covalent Bonding

  • Covalent bond: Electrostatic attraction between a shared pair of electrons and the positively charged nuclei of atoms.
  • Types of covalent bonds:
    • Single bond: One shared pair of electrons.
    • Double bond: Two shared pairs of electrons.
    • Triple bond: Three shared pairs of electrons.
  • Bond length: Decreases as the number of shared electrons increases.
  • Bond strength: Increases as the number of electrons shared increases.
  • Polarity: Results from the difference in electronegativity of the bonded atoms.

Covalent Structures

  • Lewis diagrams: Show the arrangement of electrons in covalent molecules.
  • Octet rule Atoms tend to gain a valence shell with eight electrons
  • Exceptions to octet rule: Certain elements (e.g., Be, B) form stable compounds with fewer than eight electrons in their valence shell.

Polar bonds

  • Polar covalent bonds: Result from unequal sharing of electrons due to differences in electronegativity.
  • Dipole moments occur: When bonds are polar, and are not symmetrically arranged.
  • Polar molecules: When the bond dipoles in a molecule do not cancel out.
  • Non-polar molecules: When the bond dipoles in a molecule cancel out.

Intermolecular Forces

  • London dispersion forces: Weak forces between all molecules, caused by temporary dipoles.
  • Dipole-dipole forces: Attractive forces between polar molecules.
  • Hydrogen bonds: Strong forces between molecules containing H bonded to F, O or N. These are especially strong intermolecular forces.
  • Strength comparison: London dispersion < Dipole-dipole < Hydrogen bonds.

Metallic bonding

  • Metallic bond: Electrostatic attraction between positively charged metal ions and delocalized valence electrons.
  • Properties of metals:
    • High electrical conductivity due to delocalized electrons.
    • High thermal conductivity due to delocalized electrons.
    • Malleability and ductility due to non-directional metallic bonding.
    • High melting points due to strong metallic bonds.

Alloys

  • Alloys: Mixtures of two or more metals, often with enhanced properties.
  • Examples of alloys:
    • Steel
    • Brass
    • Bronze
    • Duralumin
  • Properties of alloys:
    • Increased strength and durability
    • Improved corrosion resistance
    • Altered melting points

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Unit 4 Chemical Bonding and Structure PDF

Description

Test your knowledge on the fundamental concepts of chemical bonding including ionic and covalent bonds, Lewis structures, and hybridization. This quiz covers the properties of different bonding systems and the behavior of ions in chemical compounds.

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