AS chemistry Module 3 and 4 Flashcards
(41 cards)
What is electronegativity?
The power of an atom to attract the bonding pair of electrons in a covalent bond.
What happens when electronegativities of two atoms differ?
Electrons are pulled more to one end, creating a slight positive charge (δ+) on one atom and a slight negative charge (δ-) on the other.
What is a permanent dipole?
A difference in charge between two atoms in a covalent bond caused by the attraction of the electron pair by the more electronegative atom.
What characterizes polar bonds?
They form between atoms of different electronegativities, leading to asymmetrical electron distribution and a permanent dipole.
What characterizes non-polar bonds?
They form between atoms of similar or the same electronegativities, leading to symmetrical electron distribution and no permanent dipole.
What are ionic bonds?
Bonds formed by the complete transfer of electrons from one atom (metal) to another (non-metal).
What determines if a molecule is polar?
It contains asymmetrical polar bonds.
What makes a molecule non-polar?
It contains no polar bonds or has polar bonds that are symmetrical, canceling out the dipoles.
What is an intermolecular force?
The force arising from the interaction between molecules.
What are the three main types of intermolecular forces?
- Permanent dipole-dipole forces * Induced dipole-dipole forces (London forces) * Hydrogen bonding
What are permanent dipole-dipole forces?
Weak intermolecular forces of attraction between permanently polar molecules.
What are induced dipole-dipole forces?
Weak intermolecular forces present between all atoms and molecules due to temporary dipoles.
What are hydrogen bonds?
A special type of permanent dipole-dipole force that forms when hydrogen bonds with highly electronegative elements like nitrogen, oxygen, or fluorine.
What indicates the presence of hydrogen bonding in a molecule?
The presence of amine groups (-NH) or hydroxyl groups (-OH).
What factors determine the strength of London forces?
- Molecular size * Molecular shape * Distance between molecules
What is bond energy?
The energy needed to break one mole of a given bond in one mole of gaseous molecules.
What is bond length?
The distance between the centers of two nuclei of adjacent atoms.
How does bond length relate to bond strength?
The strength of the bond depends on the length; shorter bonds tend to be stronger.
What is an ideal gas?
A hypothetical gas whose volume varies in proportion to its temperature and inversely to its pressure.
What are the conditions for gases to behave ideally?
- High temperature * Low pressure
What is a giant covalent structure?
A structure where a large number of atoms are joined by covalent bonds, forming a giant lattice.
What are allotropes?
Different molecular or crystalline forms of the same element resulting in different physical properties.
How does diamond’s structure affect its properties?
- Very hard due to strong covalent bonds * High melting and boiling points * Good thermal conductor * Insoluble in solvents * Poor conductor of electricity
How does graphite’s structure affect its properties?
- Soft and slippery due to layered structure * High melting and boiling points * Insoluble in solvents * Good conductor of electricity due to delocalised electrons * Low density
