Topic 4/14 - Bonding

Question 1

Charge density

Answer 1

The charge per unit volume of an ionic compound.

Question 2

Ionic bond

Answer 2

electrostatic forces of attraction between oppositely-charged ions.

Question 3

How are ionic compounds formed

Answer 3

elements have a large difference in electronegativity.

Question 4

Coordination

Answer 4

the number of ions that surround a given ion in an ionic lattice (3D crystalline structure)

Question 5

Lattice enthalpy

Answer 5

The strength of the force between the ions. Depends on size and charge of ion.

Question 6

Why do ions have high melting and boiling points?

Answer 6

Strong electrostatic attraction between ions and requires high amount of energy to break.

Question 7

What 2 factors determine MP of an ionic compound

Answer 7

MP decreases as ionic radius increases, as the charge increases MP increases.

Question 8

Volatility

Answer 8

Doesn’t readily escape to vapor phase due to the strong electrostatic forces of attraction. Ionic compounds have low volatility.

Question 9

Ionic compounds are soluble in…

Answer 9

Polar covalent (water) - has a separation of charges in its structure. So, when ionic compounds are put in water, the ions are attracted to the charged water molecules so the ions dissociate in water and the lattice breaks down.

Question 10

Electrical conductivity

Answer 10

depends on the fact that ions are able to hold a charge

Question 11

Can ionic compounds conduct electricity?

Answer 11

Not in solid because the ions are firmly in the lattice and unable to move, and can’t carry charges. They can in aqueous or molten state due to free ions that can move and carry charges.

Question 12

brittleness

Answer 12

ionic compounds are brittle - crystals shatter when force is applied.

Question 13

ionic character

Answer 13

determined by the difference in electronegativity btwn atoms in the compound. Bigger difference, greater ionic character.

Question 14

Polyatomic ions

Answer 14

Has both ionic and covalent bonding. Atoms in polyatomic ion are covalently bonded and is ionically bonded to the other ion.

Question 15

Covalent bonding

Answer 15

electrostatic forces of attraction of attraction between the positively charged nucleus and the shared pair of electrons. Nonmetals - can form single double and triple bonds

Question 16

Bond length

Answer 16

measure of the distance between 2 covalently bonded nuclei. Expressed in picometers (pm).

Question 17

Bond strength

Answer 17

a measure of the energy required to break a covalent bond. measured in KJ/mol.

Question 18

Coordinate covalent bonds

Answer 18

Differ from normal bonds in the way that in a coordinate bond, both the shared electrons are provided by one of the atoms.

Question 19

single –> double –> triple bond

Answer 19

length decreases, strength increases

Question 20

Electron deficiency

Answer 20

Coordinate covalent bonds can occur when one of teh atoms is electron deficient (has less electrons in the valence shell -doesn’t satisfy the octet rule - H, He, B, Be). This means the atom has a tendency to accept an electron pair from a molecule with a lone pair.

Question 21

Electronegativity to find polarity

Answer 21

Greater electronegativity means greater attraction for electrons, so they’re pulled closer giving one atom a partial negative charge.

Question 22

VSEPR

Answer 22

The shape of a molecule is due to repulsions between pairs of e- outside the shell of the central atom.

Question 23

VSEPR bonding rules

Answer 23

molecules take shape to minimize repulsions. Lone pairs repel more than bonded pairs. double/triple bonds don’t repel more.

Question 24

Electron domains

Answer 24

places where bonds have formed or can form. determines electron geometry.

Question 25

2 domains

Answer 25

Linear (180)

Question 26

3 domains

Answer 26

Trigonal planar (120)

Question 27

4 domains

Answer 27

tetrahedral (109.5)

Question 28

5 domains

Answer 28

trigonal bipyramidal (90/120/180)

Question 29

6 domains

Answer 29

octahedral (90)

Question 30

trigonal planar with 1 lone pair

Answer 30

117 - bent

Question 31

Tetrahedral with 1 lone pair

Answer 31

107 - trigonal pyramidal

Question 32

Tetrahedral with 2 lone pairs

Answer 32

105 - bent

Question 33

Drawing Trigonal bipyramidal

Answer 33

Put lone pairs on the equatorial and start by drawing axes

Question 34

Trigonal bipyramidal with 1 lone pair

Answer 34

90 degrees from axis to equator, 117 between equatorials. Seesaw/ unsymmetrical tetrahedron.

Question 35

Trigonal bipyramidal with 2 lone pairs

Answer 35

90 - T shape

Question 36

Trigonal bipyramidal with 3 lone pairs

Answer 36

180 - linear

Question 37

Octahedral with 1 lone pair (doesn’t matter where it goes)

Answer 37

<90 - square pyramidal

Question 38

Octahedral with 2 lone pairs

Answer 38

90 - Square planar