Structure and bonding

Question 1

Electronegativity

Answer 1

the ability of an atom to attract a bonding pair of electrons in a covalent bond

Question 2

Simple molecular compounds

Answer 2

• most common crystal structure for covalent molecules
• molecules are held together as solids and liquids by forces between the molecules

Question 3

Polar bonds

Answer 3

bonds that have a permanent uneven distribution of electron density caused by a LARGE difference in electronegativity

Question 4

Hydrogen bond (intermolecular force)

Answer 4

key phrase: the electrostatic attraction in a hydrogen bond is between the lone pair on the N/O/F and the delta+ hydrogen on a different molecule attached to a N/O/F.

this attraction is between molecules and is represented as a dotted line - dotted line MUST be linear

Question 5

Giant covalent lattice

Answer 5

key phrase: giant covalent lattice contain many strong covalent bonds which causes their properties. (covalent bonds have a shared pair of electrons)

• these compounds have high melting points, are the strongest structure & bond and tend not to conduct electricity (except graphite)

Question 6

Which giant covalent structures do you need to know?

Answer 6

diamond, graphite, silicon and silicon dioxide

Question 7

Giant ionic lattice

Answer 7

key phrase: giant ionic lattices have strong electrostatic attraction between oppositely charged ions. Larger ions and lower charges have WEAKER attraction

• ionic compounds conduct electricity when melted or in solution, have high melting points and are the second strongest structure & bond

Question 8

Giant metallic lattice

Answer 8

key phrase: giant metallic lattices have strong electrostatic attraction between delocalised electrons and positively charged ions. Larger ions and lower charges have WEAKER attraction

• metallic compounds conduct electricity, have high melting points, are ductile, malleable and are the third strongest structure & bond

Question 9

Van der Waals forces (intermolecular force)

Answer 9

Key description: it is caused by a random movement of electrons causing a temporary dipole in that molecule. This partial charge then causes electron density to be attracted/repelled in other nearby molecules which induce a dipole in them.

• This IMF is found in every simple molecular compound between MOLECULES and is a non-polar IMF.

Question 10

Permanent dipole-dipole forces (intermolecular force)

Answer 10

• caused by the large difference in electronegativity between two elements in a covalent bond.
• second strongest IMF
• attraction is between MOLECULES - between the delta positive atom in one molecule and the delta negative ion in the other molecule