Bonding (old) Flashcards
1
Q
Description of ionic bonds
A
- metal and non metal
- transfer electrons
- opposite charged ions attracted by electrostatic forces
- in a giant ionic lattice structure
2
Q
Properties of ionic compounds
A
- crystalline solid at room temp
- high m.p
- only conduct electricity when motlen or dissolved, ions now free to move to carry a current throughout the structure
- brittle and shatter easily
3
Q
Why are ionic compounds brittle?
A
- because they form a lattice of alternating +/- ions, a small displacement move the ions and causes contact between ions with same charges
4
Q
Why does ionic compounds have high melting point?
A
- need a lot of energy to break the giant lattice of ions with strong electrostatic forces between + - charged ions
5
Q
Description of molecular covalent bonding
A
- in a simple molecular structure
- non metal non metal
- shared pair of electrons
6
Q
Properties of molecular covalent bonding
A
- gas and liquid in room temp.
- low m.p.
- poor solubility
- don’t conduct electricity- not charged so no free ions, no delocalised electrons
7
Q
Why is molecular Covalent bond has low m.p?
A
- weak intermolecular forces between MOLECULES so easy to break, less energy needed to overcome
- Types of forces : van der waals, permanent dipoles, hydrogen bonds
8
Q
Why is molecular covalent has low solubility ?
A
- no charged particles
- don’t interact with polar water molecules
9
Q
What affects the strength of covalent bond ?
A
- atomic radius- the bigger the atom is, the greater distance so weaker attraction between nucleus and electrons
10
Q
Factors affect strength of ionic bonds (2)
A
- charge of ions- higher charge( more protons +) = stronger attraction of nucleus and e-
- size of ions - smaller ion( smaller atomic radius ) = less distance = stronger attraction of nucleus and e-
11
Q
Description of macromolecular covalent bonding
A
- non metals x2
- shared pair of electrons
- macromolecular structure
E.g. diamond, graphite, silicon dioxide, silicon
12
Q
Properties of macromolecular covalent bond
A
- solid at room temp.
- high m.p.
- insoluble
- diamond and sand don’t conduct electricity, graphite does as free delocalised electrons between layers
- don’t conduct when molten
13
Q
Why is m.p high in macro.cov bond
A
- many strong covalent bonds in macro structure = need a lot of energy to break
14
Q
Bonding + structure of diamond
A
- each C atom bond with 4 other tetrahedral arrangement
- does not conduct electricity but good thermal conductor
- very high m.p.
- extremely hard
15
Q
Bonding + structure of graphite
A
- each C atom bond with 3 other C atoms , the 4th e- is delocalised
- hexagonal arrangement
- layered structure
- weak intermolecular forces between layers
- high m.p.
- insoluble, covalent bonds too strong to break
