EL5 (VSEPR, Covalent/Ionic Bonding + Structures)

Question 1

What are the physical properties of SCM?

Answer 1

-Low BP.
-Doesn’t dissolve in water.
-Doesn’t conduct electricity.

Question 2

What does iodine have?

Answer 2

-Strong intramolecular forces but weak intermolecular forces.

Question 3

Why are electrons arranged the way they are?

Answer 3

EPRT. They all have negative charge so they want to repel as much as possible which means they will arrange themselves as far apart as possible.

Question 4

What do solid lines represent?

Answer 4

Bonds that lie in the plane of the paper.

Question 5

What do solid, wedged shapes represent?

Answer 5

Bonds that come towards you.

Question 6

What do dashed wedges represent?

Answer 6

Bonds that go away from you.

Question 7

What is the shape with 2e- pairs, angle and bonding or lone?

Answer 7

Linear, 180* with 2 bonding pairs.

Question 8

What are the names, angles, and pairs for 3 e- pairs?

Answer 8

Trigonal planar with 120* and 3 bonding pairs.
Bent with 119* and 2 bonding pairs, 1 lone pair.

Question 9

What are the 3 shapes, angles and pairs for 4e- pairs?

Answer 9

Tetrahedral with 109.5, 4 bonding pairs.
Trigonal pyramidal with 107, 3 bonding pairs and 1 lone.
Bent with 104.5*, 2 bonding pairs and 2 lone pairs.

Question 10

What angle does trigonal bipyramidal have for 5e- pairs?

Answer 10

90/120.

Question 11

How do you use VSEPRT to predict the shape of molecules?

Answer 11

-Find the number of electrons the central atom normally has in its valence.
-Add one electron for every atom that the central is bonded to.
-Add or subtract electrons to account for charges if necessary.
-Divide the number arrived at by two for electron pairs.
-Subtract no. of atoms bonded to central to find no. of lone pairs.
-Arrange pairs in the correct shape.

Question 12

What is the order of strength of repulsion?

Answer 12

Lone pair/LP^BP/LP^BP/BP.

Question 13

What does each lone pair reduce the bond angles by?

Answer 13

Approximately 2.5 degrees.

Question 14

What are the properties of ionic compounds?

Answer 14

High melting point, dissolve in water, and conduct electricity.

Question 15

What are the properties of metallic compounds?

Answer 15

High melting point, conduct electricity, and malleable.

Question 16

Why do ionic compounds have a high melting point?

Answer 16

Lots of energy is needed to break their bonds because of the strong electrostatic attraction.

Question 17

Why do ionic compounds conduct electricity when molten or aqueous?

Answer 17

Because ions are free to move.

Question 18

Why do metallic compounds have a high melting point?

Answer 18

Because of the strong electrostatic force.

Question 19

Why metals conduct electricity?

Answer 19

Because electrons can flow.

Question 20

Why are metals malleable?

Answer 20

The electrons are arranged in layers, so they can easily slide over each other.

Question 21

explain the properties of giant covalent structures

Answer 21

they are very hard structures due to many strong covalent bonds
they have high melting and boiling points due to the covalent bonds needing high amounts of energy to break them
if delocalised electrons are present, the structure will conduct electricity

Question 22

describe and explain the structure of diamond

Answer 22

1- each carbon atom is bonded to 4 others via covalent bonds
2- diamond is hard and has a high melting/boiling point due to strong covalent bonds
3- it is a good conductor of heat because vibrations of thermal energy are rapidly transferred across the strong bonds
4- it is insoluble because the attraction between its own carbon atoms is much stronger than the potential attraction between the solvent molecules and carbon atoms
5- all valence electrons are involved in bonding pairs so it cannot conduct electricity due to no delocalisation

Question 23

describe and explain the structure of graphite

Answer 23

1- each carbon atom forms 3 covalent bonds with 3 other carbon atoms
2- carbons are organised into sheets of hexagons
3- it is soft and slippery due to the weak intermolecular forces holding layers together, this means they can slide over each other easily
4- high melting and boiling point due to covalent bonding
5- insoluble for the same reasons as diamond
6- it has a low density because there is a large distance between layers due to the weak IM forces
7- good conductor of electricity due to delocalisation

Question 24

describe and explain the structure of buckminsterfullerene

Answer 24

tiny hollow spheres of carbon atoms, each atom has 3 covalent bonds with 3 others
due to low intermolecular forces, it is soft and has a low sublimation point so it goes straight from solid to gas
conducts electricity due to delocalisation

Question 25

describe the properties of metallic structures

Answer 25

due to strong forces they have a high melting and boiling point
they are malleable and ductile as the layers of atoms can slide over each other
good conductors of heat and electricity (delocalised electrons)

Question 26

what is bond dissociation energy

Answer 26

the energy required to break one mole of a bond in a molecule into separate atoms

Question 27

describe the relation between strength of covalence and bond dissociation

Answer 27

more stable covalent bonds have higher bond dissociation energies

Question 28

the more electrons that are shared…

Answer 28

the shorter and stronger the bond

Question 29

define a dative bond

Answer 29

when both bonding electrons come from the samew atom

Question 30

in ionic bonding, which molecule loses or gains an electron

Answer 30

the non metal gains an electron, forming anions
the metal loses an electron, forming catiosn

Question 31

explain the properties of simple ionic molecules

Answer 31

the strong lattice structure makes them hard
high melting and boiling point due to strong ionic bonds
dissolve in water
brittle
conduct electricity when molten or in liquid state due to delocalisation

Question 32

describe the structure of simple ionic molecules

Answer 32

each ion is surrounded by ions of the opposite charge and arranged in a giant ionic lattice
this maximises the forces of attraction and minimises repulsive forces which contributes to the high melting/boiling pints

Question 33

ionic bonding is what reaction

Answer 33

an exothermic reaction as energy is realised when ions come together to form a compound