Bonding Flashcards

Bonding

A-Level AQA Chemistry

This pack of flashcards covers the fundamental principles of chemical bonding, including ionic, covalent, and metallic bonds. It explores the formation and properties of positive and negative ions, the factors affecting melting points, bond types and shapes, electronegativity, intermolecular forces, and the characteristics of different crystal structures. Each card provides a succinct explanation or definition on one side, with detailed information on the reverse to aid in understanding chemical structures and interactions.

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What is the main factor affecting the size of Van der Waals forces?	The number of electrons in the molecule. The more electrons, the stronger the Van der Waals forces and the higher the boiling point.
What is the shape of a molecule with linear geometry?	A molecule with linear geometry has a bond angle of 180 degrees.
Define octahedral geometry.	Octahedral geometry refers to a molecular shape with six bond pairs and no lone pairs, resulting in bond angles of approximately 90 degrees.
How can you determine the shape of a molecule with trigonal bipyramidal geometry?	A molecule with trigonal bipyramidal geometry has bond angles of approximately 119 degrees and 89 degrees.
Describe the shape of a molecule with a lone pair that reduces the bond angle.	The presence of a lone pair in a molecule can reduce the bond angle, resulting in a shape that deviates from the expected angle.
What is electronegativity?	Electronegativity is the relative tendency of an atom in a covalent bond to attract electrons in a covalent bond to itself.
Describe the factors affecting electronegativity.	Electronegativity increases across a period as the number of protons increases and the atomic radius decreases. It decreases down a group because the distance between the nucleus and the outer electrons increases and the shielding of inner shell electrons increases.
What is intermediate bonding?	Ionic and covalent bonding are the extremes of a continuum of bonding type. Differences in electronegativity between elements can determine where a compound lies on this scale.
How is a polar covalent bond formed?	A polar covalent bond forms when the elements in the bond have different electronegativities (around 0.3 to 1.7).
What determines if a molecule is polar or non-polar?	A symmetric molecule with all identical bonds and no lone pairs will not be polar. If the individual dipoles on the bonds cancel out due to the symmetrical shape of the molecule, it is non-polar.
Describe Van der Waals' forces.	Van der Waals' forces occur between all molecular substances and noble gases. They are transient, induced dipole-dipole interactions that form due to fluctuating electron density in molecules.
Describe the shape of a molecule with square planar geometry.	The molecule has a square planar shape with bond angles of approximately 90 degrees.
Define permanent dipole-dipole forces.	Permanent dipole-dipole forces occur between polar molecules. They are stronger than Van der Waals forces and result from a significant difference in electronegativity between atoms.
How do the boiling points of halogens change down the group?	The boiling points increase down the group due to the increasing number of electrons in the bigger molecules, resulting in larger Van der Waals forces.
Describe hydrogen bonding.	Hydrogen bonding occurs in compounds with a hydrogen atom attached to nitrogen, oxygen, or fluorine. These compounds must also have an available lone pair of electrons.
What causes the anomalously high boiling points of H2O, NH3, and HF?	The hydrogen bonding between the molecules causes the high boiling points.
Explain the general increase in boiling point from H2S to H2Te.	The increase in boiling point is caused by increasing Van der Waals forces between molecules due to an increasing number of electrons.
What are the four types of crystal structure?	The four types of crystal structure are ionic, metallic, molecular, and giant covalent (macromolecular).
Describe the structure of an ionic crystal.	An ionic crystal has a giant ionic lattice showing alternate Na+ and Cl- ions.
Describe the structure of a metallic crystal.	A metallic crystal has a giant metallic lattice showing close packing magnesium ions.
Describe the structure of a molecular crystal.	A molecular crystal, like ice, has regular arrangement of water molecules held together by weak van der Waals forces.
Describe the structure of a macromolecular crystal.	A macromolecular crystal, like diamond or graphite, has a giant structure with strong covalent forces and delocalized electrons.
Define metallic bonding.	Metallic bonding is the electrostatic force of attraction between positive metal ions and the delocalized electrons.
What happens to metal atoms during ionic bonding?	Metal atoms lose electrons to form positive ions.
What happens to non-metal atoms during ionic bonding?	Non-metal atoms gain electrons to form negative ions.
Compare the melting points of MgO and NaCl and explain why they differ.	MgO has a higher melting point than NaCl because the ions involved (Mg2+ and O2-) are smaller and have higher charges than those in NaCl (Na+ and Cl-).
Explain why positive ions are smaller compared to their atoms.	Positive ions are smaller because they have one less shell of electrons and the ratio of protons to electrons has increased, resulting in a greater net force on the remaining electrons.
Why are negative ions formed from groups five to seven larger than the corresponding atoms?	Negative ions have more electrons than the corresponding atoms, but the same number of protons. The pull of the nucleus is shared over more electrons, resulting in a weaker attraction per electron and making the ion bigger.
What is the relationship between the number of protons and the size of ions?	As the number of protons increases, the effective nuclear attraction per electron increases, causing ions to get smaller.
How does the size of ionic radii change within a group?	Within a group, the size of ionic radii increases going down the group because the ions have more shells of electrons.
Describe a covalent bond.	A covalent bond is a shared pair of electrons between two atoms.
What is dative covalent bonding?	Dative covalent bonding occurs when the shared pair of electrons in a covalent bond come from only one of the bonding atoms.
How does a dative covalent bond differ from an ordinary covalent bond?	A dative covalent bond is formed when the shared pair of electrons come from only one of the bonding atoms, while an ordinary covalent bond is formed when the shared pair of electrons come from both bonding atoms.
Describe ionic bonding.	Ionic bonding is the electrostatic force of attraction between oppositely charged ions formed by electron transfer.
What are the three main factors that affect the strength of metallic bonding?	The three main factors that affect the strength of metallic bonding are the number of protons/strength of nuclear attraction, the number of delocalized electrons per atom, and the size of the ion.
Describe the structure of a simple molecular substance.	A simple molecular substance consists of molecules held together by intermolecular forces such as van der Waals forces, permanent dipoles, or hydrogen bonds.
What is the property of metallic substances that allows them to conduct electricity?	Metallic substances have a high conductivity because of the presence of delocalized electrons that can move through the structure.
What is the bond angle in a linear molecule?	The bond angle in a linear molecule is 180 degrees.
Define trigonal planar.	Trigonal planar is a molecular shape with three bonding pairs and no lone pairs around the central atom.
How do lone pairs of electrons affect the shape of a molecule?	Lone pairs of electrons repel more than bonding pairs, causing a reduction in bond angles.
Describe the shape and bond angle of a tetrahedral molecule.	A tetrahedral molecule has four bonding pairs and no lone pairs, with a bond angle of 109.5 degrees.

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