Structure and bonding - higher Flashcards
What is an ionic bond
The electrostatic attraction between positive and negative ions
What type of bond forms a lattice
Ionic
What is a covalent bond
The electrostatic attraction between two Nicki and shared electrons
What is electronegativity
The measured attraction between the positive nuclei and shared electrons in a covalent bond
What elements form covalent networks
Carbon, silicon and boron
What is the electronegativity Difference scale
Pure covalent bonds have a difference of <0.5 polar covalent bonds have a difference of 0.5 -1.6 and ionic bonds have a difference of >2.0
What is the general idea for elements with an electronegativity difference of 1.6-2.0
Generally elements with a difference between 1.6 and 2.0 if a metal is involved the bind is ionic if it is only non-metals normally it is polar covalent
What is a dipole
An atom with a temporary charge
How Do London dispersión forces occur
LDF’s are a result of an electrostatic attraction between temporary dipoles and induced dipoles caused by movement of electrons in atoms and molecules
What is the collective term for intermolecular forces
Van der walls forces
What is a permanent dipole-permanent dipole interaction
PD-PD interactions are additional electrostatic attractions between polar molecules. They are stronger than LDF’s
What is a hydrogen bond
Bonds consist of a hydrogen bond and either oxygen nitrogen or fluorine creating a highly polar molecule
Why does hydrogen bonds require the most energy to break
They are the strongest of the van der wall forces
How do hydrogen bonds effect solubility
The more hydrogen bonds in a molecule the more soluble it is in water
Why does ice have a lower density than liquid water
Ice has an expanded hexagonal structure causing gaps making it less dense than water
