Bonding And Structure

Question 1

What is ionic bonding?

Answer 1

The bonding of thousands of cations and anions together to form a regular, repeating three-dimensional giant lattice of oppositely charged ions.

Ionic bonding occurs due to the electrostatic attraction between oppositely charged ions

Question 2

Define lattice in the context of ionic compounds.

Answer 2

A regular arrangement of ions.

Question 3

What property do ionic substances exhibit due to their giant lattice structure?

Answer 3

High melting points.

Question 4

Why are ionic substances hard when in the form of a crystal?

Answer 4

Due to strong forces of attraction between the ions.

Question 5

Are ionic compounds water soluble?

Answer 5

Yes.

Water molecules attract the ions, and the energy released is sufficient to overcome the ionic bonds.

Question 6

Fill in the blank: Ionic compounds are ______ in non-polar solvents like hexane.

Answer 6

Insoluble.

The weak attraction between covalent molecules and ions is not enough to overcome ionic bonds.

Question 7

What is a characteristic of ionic compounds when dissolved in water or molten?

Answer 7

They act as electrolytes.

The ions are free to move, allowing them to conduct electricity.

Question 8

True or False: Solid ionic compounds can conduct electricity.

Answer 8

False.

In solid form, the ions are fixed in the lattice and cannot move.

Question 9

What happens when a force is applied to an ionic crystal?

Answer 9

One layer of ions shifts relative to another, causing ions of the same charge to be opposite each other.

This results in a repulsive force that forces the layers apart.

Question 10

How many other ions typically surround each ion in an ionic compound?

Answer 10

6 or 8 other ions.

This arrangement contributes to the stability of the ionic lattice.

Question 11

What is an ionic bond?

Answer 11

The electrostatic force of attraction between two oppositely charged ions

Ions are atoms or molecules that have gained or lost one or more electrons, resulting in a net charge.

Question 12

What should you draw if asked to ‘show the bonding in..’?

Answer 12

You only need to draw the ions with their charges.

Question 13

What should you draw if asked to ‘show the formation of..’?

Answer 13

You have to draw the atoms and the ions.

Question 14

What is the definition of a covalent bond?

Answer 14

A covalent bond is the electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms.

Question 15

What is the octet rule?

Answer 15

When forming a compound, an atom tends to gain, lose, or share electrons to achieve eight electrons in their outer shell.

Question 16

True or False: Some molecules have atoms that deviate from the octet rule.

Answer 16

True

Question 17

What is the contraction of the octet?

Answer 17

Beryllium and boron form compounds with covalent bonds, having fewer than eight electrons in their outer shell.

Question 18

Give an example of a molecule that demonstrates the contraction of the octet.

Answer 18

Boron trifluoride

Question 19

What is the expansion of the octet?

Answer 19

Some bonding atoms can have more than eight electrons in the outer shell.

Question 20

Provide an example of a molecule that can expand its octet.

Answer 20

Sulfur hexafluoride

Question 21

What is the definition of a co-ordinate bond?

Answer 21

A covalent bond in which both electrons are donated by the same atom

A coordinate bond is also known as a dative covalent bond.

Question 22

What symbol is used to represent a dative covalent bond?

Answer 22

An arrow

The arrow points from the atom donating the pair of electrons to the atom receiving them.

Question 23

What is the ammonium ion formula?

Answer 23

NH₄⁺

The ammonium ion is formed when a nitrogen atom shares its lone pair of electrons with a hydrogen ion.

Question 24

What is the definition of electronegativity?

Answer 24

The ability of an atom to attract a pair of electrons in a covalent bond to itself.

Question 25

How does electronegativity change across a period?

Answer 25

Electronegativity increases across a period.

Question 26

What happens to electronegativity as you move down a group?

Answer 26

Electronegativity decreases down a group.

Question 27

What causes electronegativity to increase across a period?

Answer 27

The charge on the nucleus increases and the bonded electrons are closer to the nucleus.

Question 28

What causes electronegativity to decrease down a group?

Answer 28

The size of the atom increases, making bonded electrons further from the nucleus.

Question 29

Fill in the blank: Electronegativity increases across a _______.

Answer 29

period.

Question 30

Fill in the blank: Electronegativity decreases down a _______.

Answer 30

group.

Question 31

True or False: A higher electronegativity value indicates a weaker ability to attract electrons.

Answer 31

False.

Question 32

True or False: Electronegativity is a measure of an atom's ability to attract electrons in a covalent bond.

Answer 32

True.

Question 33

What type of bond is formed when there is a big difference in electronegativity values between elements?

Answer 33

Ionic bond

Question 34

What type of bond is formed when the difference in electronegativity is smaller?

Answer 34

Covalent bond

Question 35

The relationship between electronegativity difference and bond type can be summarized as: the bigger the difference, the more _______.

Answer 35

Ionic ## Footnote This indicates a stronger tendency for electron transfer.

Question 36

The smaller the difference in electronegativity, the more _______ the bond is.

Answer 36

Covalent ## Footnote Covalent bonds involve the sharing of electrons between atoms.

Question 37

What is the term for bonding electrons that are unequally shared between atoms?

Answer 37

Polar bonds ## Footnote Polar bonds occur due to differences in electronegativity between atoms.

Question 38

Which atom is more electronegative in the H-Cl bond?

Answer 38

Chlorine ## Footnote Chlorine's higher electronegativity leads to a polar bond with hydrogen.

Question 39

What are bond polarities also referred to as?

Answer 39

Dipoles

Question 40

Is water a polar or non-polar molecule?

Answer 40

Polar ## Footnote Water's bond polarities do not cancel, resulting in a polar molecule.

Question 41

Is boron trichloride (BCl3) a polar or non-polar molecule?

Answer 41

Non-polar ## Footnote BCl3 is symmetrical, causing the polar B-Cl bonds to cancel each other.

Question 42

What is the reason for BCl3 being classified as non-polar despite having polar bonds?

Answer 42

Molecule is symmetrical ## Footnote The symmetry of BCl3 allows for cancellation of dipoles.

Question 43

What is a simple covalent molecule?

Answer 43

A simple covalent molecule consists of a small number of atoms that are covalently bonded together.

Question 44

What are the physical states of simple covalent substances?

Answer 44

Gases, liquids, or easily melted solids. They typically have low melting and boiling points.

Question 45

What is a characteristic of simple covalent substances when in crystal form?

Answer 45

Soft. This is due to the weak forces between the molecules.

Question 46

Are simple covalent substances soluble in water?

Answer 46

No, they are water insoluble.

Question 47

In what type of solvents are simple covalent substances soluble?

Answer 47

Non-polar solvents, e.g., hexane. ## Footnote This is because non-polar substances dissolve in non-polar solvents.

Question 48

What type of electrolytes are simple covalent substances?

Answer 48

Non-electrolytes. ## Footnote They do not dissociate into ions in solution.

Question 49

What is the reason for the low melting and boiling points of simple covalent substances?

Answer 49

The forces of attraction between molecules are weak. Little energy is needed to break these weak intermolecular forces.

Question 50

Do simple covalent substances conduct electricity?

Answer 50

No, they do not conduct electricity. ## Footnote This is because there are no mobile ions or electrons.

Question 51

What happens to molecular covalent substances when melted?

Answer 51

The molecules break free from their lattice positions. ## Footnote The weak intermolecular forces are overcome, but intramolecular covalent bonds remain intact.

Question 52

What are van der Waals' forces?

Answer 52

Weak intermolecular forces between molecules. ## Footnote They are responsible for the physical properties of simple covalent substances.

Question 53

What type of bond is stronger in simple covalent substances?

Answer 53

Covalent bond. ## Footnote This bond occurs within the molecules, while van der Waals' forces act between them.

Question 54

True or False: Simple covalent substances can conduct electricity when dissolved in hexane.

Answer 54

False.

Question 55

Fill in the blank: Simple covalent substances are ______ in non-polar solvents.

Answer 55

soluble.

Question 56

What are giant covalent substances?

Answer 56

Giant covalent substances are formed when non-metal atoms join together by covalent bonds to create large structures or crystals.

Question 57

What are two examples of giant covalent molecules?

Answer 57

* Diamond * Graphite

Question 58

What is the hardest known substance?

Answer 58

Diamond

Question 59

What is the bond angle in the tetrahedral structure of diamond?

Answer 59

109°

Question 60

Why is diamond considered very hard?

Answer 60

Each carbon is bonded to 4 others. A lot of energy is needed to break the covalent bonds in its tetrahedral structure.

Question 61

Does diamond conduct electricity? True or False?

Answer 61

False

Question 62

Why does diamond not conduct electricity?

Answer 62

It does not have delocalised electrons to move and carry charge.

Question 63

Describe the structure of graphite.

Answer 63

Graphite has a layered structure with carbon atoms bonded in hexagons. Each carbon is bonded to 3 others

Question 64

What type of bond connects carbon atoms within a layer of graphite?

Answer 64

Strong covalent bonds

Question 65

What is the bond angle in graphite layers?

Answer 65

120°

Question 66

What forces hold the layers of graphite together?

Answer 66

Weak van der Waals' forces

Question 67

Why can the layers in graphite slide over one another?

Answer 67

Because the van der Waals' forces are weak, requiring little energy to break.

Question 68

What property of graphite allows it to be used as pencil lead?

Answer 68

It is soft and flaky.

Question 69

Can graphite conduct electricity? True or False?

Answer 69

True

Question 70

Why can graphite conduct electricity?

Answer 70

It has delocalised electrons that can move and carry charge.

Question 71

What is metallic bonding?

Answer 71

Metals are giant lattices of positive ions surrounded by a 'sea' of delocalised electrons.

Question 72

Define metallic bond.

Answer 72

Electrostatic attraction between the delocalised electrons and the positive ions.

Question 73

What property of metals allows them to be good conductors of electricity?

Answer 73

The delocalised electrons are free to move and carry charge.

Question 74

Why are metals considered good thermal conductors?

Answer 74

The delocalised electrons can move and transmit kinetic energy through the lattice.

Question 75

What leads to the high melting and boiling temperatures of metals?

Answer 75

A lot of energy is needed to separate the strong electrostatic attraction between the delocalised electrons and the positive ions.

Question 76

What does it mean for metals to be malleable and ductile?

Answer 76

The positive ions can slide over each other without disrupting the metallic bond. This allows metals to be shaped and stretched without breaking.

Question 77

What type of structure do the first three elements in period 3 have?

Answer 77

Metals

Question 78

What type of structure does silicon have?

Answer 78

Giant covalent structure

Question 79

What type of structure do phosphorus, sulfur, and chlorine exist as?

Answer 79

Simple molecules

Question 80

What type of bonding occurs in sodium (Na)?

Answer 80

Metallic Characterized by strong forces between positive ions and delocalized electrons.

Question 81

What type of bonding occurs in silicon (Si)?

Answer 81

Covalent Strong bonds between atoms in a giant covalent structure.

Question 82

What type of forces exist in chlorine (Cl2)?

Answer 82

Weak intermolecular forces Covalent bonding within molecules and intermolecular forces between molecules.

Question 83

How does the melting point trend from sodium to aluminum?

Answer 83

Increases Due to increasing delocalized electrons and ionic charge.

Question 84

What is the trend in ionic charge from sodium to aluminum?

Answer 84

Increases

Question 85

What happens to the number of outer-shell electrons from sodium to aluminum?

Answer 85

Increases

Question 86

What effect does increasing ionic charge have on melting and boiling points?

Answer 86

They increase Greater attraction between delocalized electrons and ions results in higher melting and boiling points.

Question 87

Fill in the blank: The melting points of elements in period 3 generally ______ as you move from sodium to aluminum.

Answer 87

Increase

Question 88

True or False: Argon has a giant covalent structure.

Answer 88

False ## Footnote Argon is monatomic and does not have a giant covalent structure.

Question 89

What is the bonding type in magnesium (Mg)?

Answer 89

Metallic Similar to sodium and aluminum with strong forces between ions and electrons.

Question 90

What is the relationship between ionic size and ionic charge?

Answer 90

Ionic size decreases as ionic charge increases Higher charge leads to stronger attraction, pulling electrons closer.

Question 91

What is a metalloid?

Answer 91

A semi-metal with a giant covalent structure similar to diamond.

Question 92

How is silicon (Si) structured?

Answer 92

Each Si is bonded to four others by strong covalent bonds.

Question 93

Why does silicon have a high melting point?

Answer 93

The strong covalent bonds require a lot of energy to break.

Question 94

What is the trend in melting points from Si to Ar?

Answer 94

There is a general decrease in melting point.

Question 95

What type of molecules are phosphorus (Pa), sulfur (S), and chlorine (Cl)?

Answer 95

Simple covalent molecules.

Question 96

What type of forces exist between Pa, S, and Cl molecules?

Answer 96

Weak van der Waals' forces.

Question 97

Why does the melting point increase slightly between phosphorus and sulfur?

Answer 97

Sulfur contains more electrons than phosphorus, resulting in stronger van der Waals' forces. Phosphorus is P4 while sulfur is S8

Question 98

Which group of elements has the lowest melting points in any period?

Answer 98

The noble gases.

Question 99

What is the reason for the low melting points of noble gases?

Answer 99

Weak van der Waals' forces between atoms require little energy to break.

Question 100

Why are Na, Mg, and Al good conductors of electricity?

Answer 100

Delocalised electrons can move and carry charge.

Question 101

Why is aluminum (Al) more conductive than sodium (Na) and magnesium (Mg)?

Answer 101

Al has more delocalised electrons.

Question 102

How is silicon classified in terms of conductivity?

Answer 102

Metalloid. As a semi-metal and a semi-conductor.

Question 103

Why is silicon considered a semi-conductor?

Answer 103

Its conductivity is in between that of a metal and a non-metal.

Question 104

Which non-metals are classified as non-conductors?

Answer 104

P4, S8, Cl2 and Ar.

Question 105

What is the reason non-metals like P4, S8, Cl2 and Ar are non-conductors?

Answer 105

They have no delocalised electrons to move and carry charge.