Structure And Bonding

Question 1

What are simple molecular substances

Answer 1

Small clusters of two or more atoms Joined together giving them low melting and boiling points . Although there are strong bonds within the molecules the forces between the molecules are weak and do not require much heat energy to overcome them

Question 2

What are giant structures

Answer 2

Substances with an unlimited continuous lattice of particles with strong bonding throughout the structure . This gives them
High melting and boiling points so a lot of heat energy is needed to overcome this strong bond

Question 3

How are ionic compounds arranged

Answer 3

Giant ionic structure in a lattice through syringe electrostatic forces between the charged ions

Question 4

Why do ionic compounds have high melting and boiling points

Answer 4

Giant structure with strong electrostatic attraction between oppositely charged ions makes them difficult to break

Question 5

Why are ionic compounds hard

Answer 5

Strong Electro static attraction between oppositely charged ions makes them difficult to break apart

Question 6

Why are ionic compounds brittle

Answer 6

To reshape a solid ,layers of particles must slide past each other . This slides positive over postive which then repel each other and the crystal shatters

Question 7

Why are ionic compounds soluble in polar solvents

Answer 7

Charged end of solvent molecules are attracted to the ions in the solid and pull them away from other ions in the lattice

Question 8

Why are they electrical conductors when molten or in solution

Answer 8

When an ionic solidis melted or dissolved the ions break free from the lattice and are able to move around . The free moving charged particles enable the liquid or solution to conduct electricity

Question 9

What happenes to the melting point of an ionic substance

Answer 9

More charges means more attraction and therefore more heat energy is required to break the bonds

Question 10

Where is metallic bonding found

Answer 10

In all metals and alloys

Question 11

What happens in metallic bonding

Answer 11

Each metal looses its outer shell electrons and becomes a positive ion. The positive ions are packed in a lattice and the cloud of delocalised electrons move throughout the entire metal .the electrostatic attraction between the positive metal ions and the cloud of delocalised electrons holds the metal together

Question 12

Why have metallic compounds for high melting boiling points and are strong

Answer 12

Giant structure with strong electrostatic forces between positive metal ions and delocalised electrons requires a large amounts of heat energy to break

Question 13

Why are metallic compounds malleable

Answer 13

The layers of metal ions can slide over each other easily without disrupting the metallic bonding ,the metal still consists of a regular lattice of positive metal ions surrounded by a cloud of delocalised electrons

Question 14

Why are metallic bonding electrical compounds

Answer 14

Cloud of delocalised electrons is free to move through the entire metal carrying the electric current

Question 15

How are covalent substances structured

Answer 15

Most are simple covalent molecules but some are giant covalent structures

Question 16

Why do simple covalent molecules have low melting and boiling points

Answer 16

Strong covalent bonds between atoms to form molecules but weak intermolecular forces which require little energy to overcome

Question 17

Why are Simple covalent molecules soft

Answer 17

To break apart a simple molecular solid it is not necessary to break the strong covalent bonds that hold the atoms together but only the weak intermolecular forces which requires a small force

Question 18

Why are simple covalent molecules electrical insulators

Answer 18

There are no ions present and all electrons are localised on atoms or in the covalent bonds so there are no free moving particles to carry the electric current

Question 19

Why are covalent molecules soluble in non polar solvents

Answer 19

Do not contain ions so are mole soluble in non polar solvents

Question 20

How is diamond structures

Answer 20

Giant lattice which each carbon forimung 4 covalent bonds

Question 21

Why had diamond and graphite got a high sublimation temperature

Answer 21

To break down the giant structure requires strong covalent bonds between the atoms to be broken which requires a large amount of heat energy . This results in single carbon atoms with no bonds between them so turns directly to gas

Question 22

Why is diamond hard

Answer 22

To break the structure requires a large number of strong covalent bonds to be broken which requires a large force

Question 23

Why is diamond and graphite insoluble in all solvents

Answer 23

To dissolve the substance would require strong covalent bonds between the atoms and no solvent is strong enough for this

Question 24

Why is diamond an electrical insulator

Answer 24

All electrons are localised in covalent bonds so there are no free moving charges particles to carry an electric current

Question 25

What are uses of diamond

Answer 25

Coating saw blades and drill bits extreme hardness allows it to cut through Anything

Question 26

How is graphite arranged

Answer 26

Later lattice each carbon atom forming 3 covalent bonds to carbon atoms

Question 27

Why is graphite soft

Answer 27

Covalent bonds within the layers are difficult to break but each layer is held next to each other by weak forces so the layers are therefore easily separated

Question 28

Why is graphite an electrical conductor

Answer 28

Each carbon forms only 3 bonds leaving one free electron that can move throughout the structure and carry an electric current

Question 29

What are uses if graphite

Answer 29

Lubricating oils ,pencil lead as the weak forces between layers allows the layers to slide over each other easily or rub onto paper

Question 30

What does an alloy do

Answer 30

Different sized atomms distort the layers in the structure and make it harder for atoms to slide over each other

Question 31

What does more free electrons do to electrical conductivity

Answer 31

Increases as there are more free electrons for current to flow through . Higher atomic number within groups means better electrical conductor

Question 32

Why are metals malleable

Answer 32

If a large force is applied the layers of atoms slide over each other and stay in their new positions as the cloud of delocalised electrons continues to attract and hold the positive joins together