Chemical Bonding and Structure

Question 1

What is metallic bonding

Answer 1

Is the electrostatic forces of attraction between metal cations and a sea of delocalised electrons

Question 2

What are the 5 properties of metals

Answer 2

• conduct electricity
• malleable
• ductile
• high melting and boiling temperatures,
• good thermal conductors

Question 3

What effects the ability of metals to conduct electricity and melting point

Answer 3

The more delocalised electrons there are the better they conduct electricity and the higher the melting point

Question 4

What is ionic bonding

Answer 4

•Is the electrostatic forces of attraction between oppositely charged ions

Question 5

The strength of ionic bonding depends on

What has this got to do with charge density

Answer 5

The bigger the charge on the ion, the stronger the electrostaic forces between ion

The smaller the ion, the stronger the electrostattic attraction between ions, as they can pack together more tightly

Having a small ion and large charge, will lead to a high charge density

Question 6

Does ionic radii, increase or decrease down a group

Answer 6

•Ionic radii increases down group

Due to the addition of electron shells, so ionic radii increases

Question 7

What are the 3 main properties of ionic compounds

Answer 7

high relatively high melting temperatures due to strong electrostaitc forces

can conduct electricity when molten or in aqueous solutions due to ions being able to move around

brittle, as layers can slide

Dissolve in water, as water molcules are polar, and attract the negative and positive ions

Question 8

Are ionic compounds soluable in water

and why

Answer 8

• Ionic compounds are soluble in water because the positive ions will separate and becomes surrounded by electronegative oxygen molecules forming and ion-dipoles interaction.
• Negative ions will be removed from the lattice and become surrounded by hydrogen molecules forming hydrogen bonds.
• The energy for this is supplied by hydration energy

Question 9

Evidence for ionic compounds can be found where

Answer 9

via electrolysis where the ionic molecules is dissolved in water and the positive ions will move toward the anion and the negative ions move towards the cation

Question 10

What is covelent bonding

Answer 10

Is the electrostatic forces of attraction between nuclei of two atoms and the bonding pairs of electrons

Question 11

How are covelent bonds formed

Answer 11

formed the overlap out their outer shell orbitals containing a single electrons

Question 12

The area of overlap 2S orbitals is called

Answer 12

a sigma bond

Question 13

The area of overlap in 2P orbitals is called a

Answer 13

Sigma bond

Question 14

The area of overlap sideways between two P orbitals is called

Answer 14

Pi bond

Question 15

A pi bond results in a what in a covalent bond

Answer 15

high electron density above and below the molecule

Question 16

Bond length is

Answer 16

Is the distance between two nuclei of the two atoms covalently bonded

Question 17

Bond strength is determined by

Answer 17

the amount of energy required to break a mole of bonds in gaseous state

Question 18

The stronger the bond, the longer or shorter the length ?

Answer 18

•The stronger the bond the shorter the length

Question 19

Nuclei with increased what, will have a greater bond strength

Answer 19

electrostatic attraction

Question 20

What is electronegativity

Answer 20

•Is the ability of an atom to attract a bonding pair of electrons

Question 21

What is the trend in electronegativity down a group and across a period

Answer 21

•This decreases down a group and increases across a period

Question 22

Do molecules of the same element have the same or different distribution of electron density?

Answer 22

•Molecules of the same element have the same distribution of electron density

Question 23

What is a polar covelent bond

Answer 23

•Polar covalent bonds is where there is a unsymmetrical distribution in electron density, due to a covalent bond with one atom carrying a slightly negative change and the other one positive

Question 24

A polar covalent bond, is a covalent bond with a degree of

Answer 24

ionic character

Question 25

What is a discrete molecule

Answer 25

* Is an electrically neutral group of two or more atoms held together by chemical bonds * This means that the central atom does not have to have a full outer shell of electrons when covalently bonded

Question 26

What is a dative covalent bond

Answer 26

* Is formed when an empty orbital of one atoms overlaps with an orbital containing a non bonded pair of electrons * Represented by an arrow

Question 27

What are the 3 rules of electron repulsion theory

Answer 27

* The shape of a molecules is cased by repulsion between pairs of electrons both bonded and non bonded * Electrons surrounds themselves around the central atom where repulsion is at a minimum * Lone pair – lone pair\> lone pair – bonded pair\> bonded pair – boned pair

Question 28

Name the bond name and angle of a molecule with 2 bonds 0 lone pairs

Answer 28

linear molecules 180 degrees

Question 29

Name the bond name and angle of a molecule with 2 Bonds 2 Lone pairs

Answer 29

V-shaped 104.5 degrees

Question 30

Name the bond name and angle of a molecule with 3 Bonds 0 Lone Pairs

Answer 30

trigonal planar 120 degrees

Question 31

Name the bond name and angle of a molecule with 3 Bonded pairs 1 lone pair

Answer 31

trigonal pyramidal 107.5

Question 32

Name the bond name and angle of a molecule with 3 Bonds 2 Lone pairs

Answer 32

trigonal bipyramidal = 104.5

Question 33

Name the bond name and angle of a molecule with 4 Bonds 0 Lone pairs

Answer 33

tetrahedral 109.5

Question 34

Name the bond name and angle of a molecule with 6 Bonded pairs 0 Lone pairs

Answer 34

Octagonal 90 and 180 degrees

Question 35

What is a polar molecule

Answer 35

•Polar molecules are molecules which have an unsymmetrical distribution of electron density caused by dipoles reinforcing another

Question 36

Explain how an instantaneous dipole is formed

Answer 36

* If molecules possess a permanent dipole, will also interact with one another, and when aligned correctly there will be a favourable interaction and attract another. * However random movement of atoms mean they are not always aligned

Question 37

When does a hydrogen bond occur

Answer 37

•When hydrogen is bonded with a more electronegative atom than itself like oxgen, nitrogen and fluorine

Question 38

What groups will form hydrogen bonds

Answer 38

•All compounds containing –O-H group

Question 39

What are the hydrogen bonds in water described as

Answer 39

•Interaction is of an extreme dipole-dipole interaction and utilising lone pair on oxygen atom

Question 40

The bond angle in water is

Answer 40

•Bond angle has to be 180 degrees

Question 41

Two main features of water due to hydrogen bonding

Answer 41

a very high boiling temperature low density as a solid than liquid

Question 42

Why will water have a higher boiling point than other molecules with hydrogen bonds

Answer 42

•Water forms two hydrogen bonds per molecule so hydrogen bonding more extensive, hence high boiling temp

Question 43

Why is the density of ice less than of liquid water

Answer 43

•When frozen, ice is arranged in 6 rings, held together by hydrogen bonds, which creates a large area open space

Question 44

Why does boiling temperture increase with chain length in alkanes

Answer 44

* More electrons per mole so London forces will be stronger * As the chain length increases there will be more point of contact, meaning and London forces between chains too

Question 45

Why do alcohols have higher boiling points that alkanes And how can we test this

Answer 45

* Alcohols also have hydrogen bonding which increases boiling tempertures * Enthalpy change of vaporisation direct measure of intermolecular interactions, you can use it to work out the predominate bonding in alcohols

Question 46

Why are alcohols soluable in water

Answer 46

•These Hydrogen bonds can form with water

Question 47

What is the trend in solubility as chain length increases

Answer 47

solubility of alcohols decreases with increasing hydrocarbon chain length as London force becomes predominant

Question 48

What is the trend with boiling point in halogen haildes

Answer 48

•Increase in HF then decreases to HCl and then continues with a steady increase with HBr and HI

Question 49

Why from HCl to HI will there be a steady increase in boiling points

Answer 49

•The steady increase from HCL to HI due to the increasing amount of electrons which increases London forces

Question 50

Why is HF boiling point extraodinarily high compared to other halogen halides

Answer 50

•HF has a very high boiling temp due to F having the highest electronegativity which effects the strength of hydrogen bonds

Question 51

In order for a substance to dissolve

Answer 51

Solute particles must be separated from another and come surrounded by solvent particles Forces of attraction between solute-solvent particle must be strong enough to overcome solvent-solvent solute-solute forces

Question 52

How would you find a solvent for a non-polar molecule

Answer 52

If you’re searching for solvent for non-polar substance that has substantial non polar parts then liquid that contains similar molecules is the answer

Question 53

what are th 4 types of soild lattices

Answer 53

•Giant metallic, giant ionic, giant covalent, discrete molecular lattice

Question 54

What are the four types of giant covalent lattices

Answer 54

Dimond, Graphite, graphene, fullerene

Question 55

Describe the bonding in dimond

Answer 55

each carbon contains 4 sigma bonds to 4 other carbons, in a tetrahedral arrangement Very hard due to the double carbon- carbon bonds

Question 56

Describe the bonding the Graphite

Answer 56

Each carbon bonded to three other sigma bonds, forming hexagonal rings. It has a deloclised electron in the p orbital. It is a solid lubricant due to absorbed gases. London forces between layers

Question 57

Decribe the bonding and melting/tempertures in Molecular solids (fullerene)

Answer 57

low melting and boiling temperatures, as not breaking the covalent bonds, bigger macro molecules have more electrons so higher London forces

Question 58

•Intermolecular interaction are relatively stonger or weaker than electrostatic forces of attraction?

Answer 58

•Intermolecular interaction are relatively **weaker** than electrostatic forces of attraction

Question 59

What creates instaneous dipole-dipole interactions

Answer 59

•London Forces create instantaneous dipole-dipole interactions, which caused by fluctuations in adjacent molecules, produced very rapidly

Question 60

London forces depend on what

Answer 60

* London forces depend on the size/shape of molecules * (more points of contact between molecules greater forces e.g. unbranched molecules) * number of electrons however they are always present in a molecules.

Question 61

As the atomic number increase in isoelectric ions, what happens to the ionic radii

Answer 61

Decreases Charges increases, meaning nuclear charge increases N^3-, O^2-, F^-, Na⁺, Mg²⁺, Al³⁺