Particles Of Which Substances Are Made

Question 1

What kind of structure does an ionic substance form?

Answer 1

An ionic crystal lattice

Question 2

What is an ionic crystal lattice?

Answer 2

A giant 3D structure consisting of billions of ions

Question 3

What kind of force holds an ionic crystal lattice together?

Answer 3

Electrostatic force

Question 4

What is an electrostatic force?

Answer 4

The force of attraction between negative and positive ions

Question 5

What is the magnitude of an electrostatic force?

Answer 5

It is very strong

Question 6

What phase are ionic compounds at room temperature?

Answer 6

Solids

Question 7

What kind of melting point does an ionic compound have?

Answer 7

High

Question 8

Why do ionic compounds have high melting points?

Answer 8

It takes a lot of energy to overcome the electrostatic forces holding the solid together

Question 9

Can ionic compounds conduct electricity?

Answer 9

Not in solid form

Question 10

Why can’t a solid ionic compound conduct electricity?

Answer 10

The ions are not free to move

Question 11

When can ionic compounds conduct electricity?

Answer 11

When they are molten

When they are dissolved

Question 12

Why can ionic compounds conduct electricity when molten or dissolved?

Answer 12

The ions are now free to move around and act as charge carriers

Question 13

What is an electrolyte?

Answer 13

A solution that has dissolved ions in it

i.e a solution that can conduct electricity

Question 14

What is dissociation?

Answer 14

When the lattice of an ionic compound is broken up

Question 15

Why are solid ionic compounds brittle?

Answer 15

They break easily

Question 16

Why do solid ionic compounds break easily?

Answer 16

When pressure is put on them
The layers of ions move
Like charged ions line up
The electrostatic repulsion break the crystal

Question 17

What two kinds of structures can covalent substances form?

Answer 17

Covalent molecular structures

Covalent network structures

Question 18

What are covalent molecular structures?

Answer 18

Structures made out of covalent molecules

Question 19

What are intramolecular forces?

Answer 19

The force of attraction existing within a covalent molecule

Question 20

What is the general magnitude of intramolecular forces?

Answer 20

Strong

Question 21

What is a polar molecule?

Answer 21

A molecule consisting of atoms, where one atom has a greater electronegativity than the other
The bonding pair is more strongly attracted to that atom

Question 22

What is a non-polar molecule?

Answer 22

A molecule consisting of atoms, where the atoms have an equal electronegativity
The bonding pair is perfectly shared between them

Question 23

What does a polar covalent bond cause?

Answer 23

The more electronegative atom will be more negatively charged
The other atom will have a slightly positive charge

Question 24

What are intermolecular forces?

Answer 24

The forces existing between covalent molecules

These forces hold the crystal lattice of covalent molecular structures together

Question 25

What is the general magnitude of intermolecular forces?

Answer 25

Weak

Question 26

Why are covalent molecular structures easy to break apart and have low melting points?

Answer 26

The intermolecular forces are weak and easy to break

Question 27

What is the general melting point of a covalent molecular structure?

Answer 27

Low

Question 28

Why does water have a greater density than ice?

Answer 28

The intermolecular forces present in the solid phase result in an open tetrahedral structure, which takes up more space

Question 29

Why does ice float on water?

Answer 29

Its density is less than that of water

Question 30

Do covalent molecular structures conduct electricity?

Answer 30

No

Question 31

What are covalent network structures?

Answer 31

Substances consisting of non-metal atoms covalently bonded to non-metal atoms

Question 32

What kind of melting points do covalent network structures have?

Answer 32

Extremely high

Question 33

What is an example of a covalent network structure?

Answer 33

Carbon

Question 34

What does it mean when a substance has an allotrope?

Answer 34

It has more than one crystalline form

Question 35

What is an example of an allotrope?

Answer 35

Carbon | It can form both diamond and graphite

Question 36

Why is diamond such a hard substance?

Answer 36

Each carbon atom is bonded to four other carbon atoms

Question 37

What is the melting point of diamond?

Answer 37

3500° C

Question 38

How does graphite differ from diamond? (On a molecular level)

Answer 38

In graphite, the carbon atoms are only bonded to three other carbon atoms This causes the structure of graphite to occur in layers

Question 39

Why is graphite so much softer than diamond?

Answer 39

The bonds between the layers of carbon atoms are very weak | They can easily slide over one another

Question 40

Why can graphite conduct electricity?

Answer 40

The fourth valence electron of graphite is free to move around

Question 41

What are the properties of covalent network structures?

Answer 41

Extremely high melting points Solid at room temperature Hard (except graphite) Do not conduct electricity (except graphite)

Question 42

What is the lattice of a metal like?

Answer 42

Regularly spaced positive ions held together by the force of attraction between these positive ions and the 'sea' of negative electrons

Question 43

What are the properties of metallic substances?

Answer 43

Conductors of both heat and electricity Malleable and ductile High density Have lustre

Question 44

Why are metallic substances malleable and ductile?

Answer 44

The force of attraction existing in its lattice still exists under these conditions

Question 45

Why do metallic substances have a high density?

Answer 45

The atoms are packed closely together

Question 46

Why do metals have lustre?

Answer 46

The loosely bound electrons reflect all frequencies of light | This causes a photoelectric effect (shine of a metal)

Question 47

What is an example of an ionic compound?

Answer 47

Sodium chloride | NaCl

Question 48

What are three examples of a covalent molecular structure?

Answer 48

Dry ice (CO2(s)) Iodine (s) Ice (H2O(s))

Question 49

What are the main differences between a covalent network and a covalent molecular structure?

Answer 49

Covalent network: atoms covalently bonded | Covalent molecular: molecules with intermolecular forces holding them together

Question 50

What kind of particles exist in a metallic crystal lattice?

Answer 50

Positive metal ions

Question 51

What force holds a metallic crystal lattice together?

Answer 51

Metallic bond

Question 52

What is a metallic bond?

Answer 52

The force existing between the ions and the delocalised electrons

Question 53

Give two examples of a metallic crystal lattice?

Answer 53

Sodium (Na) | Silver (Ag)