Bonding and Structure

Question 1

what is a cation and anion

Answer 1

cation= positive ion
anion= negative ion

Question 2

what is the perfect ionic model?

Answer 2

Ionic compounds that are composed of cations and anions arranged in a lattice

Question 3

define an ionic bond

Answer 3

Electrostatic attraction between anions and cations in a lattice

Question 4

How does ionic radii change down a group

Answer 4

Ionic radii decreases down a group as the number of electron shells increase

Question 5

define isoelectronic

Answer 5

same electronic configuration

Question 6

how are isoelectronic cations different to isoelectronic anions

Answer 6

isoelectronic anions a larger due to having more electrons

Question 7

properties of ionic solids

Answer 7

• cannot carry charge
  -cannot conduct electricity

Question 8

properties of ionic liquids

Answer 8

-can carry charge
-can conduct electricity

Question 9

properties of ionic gasses

Answer 9

-cannot conduct electricity
-cannot carry charge

Question 10

how does the strength of ionic bonds affect Mp/Bp

Answer 10

Ionic compounds with stronger ionic bonds have a higher Mp/Bp as there is stronger electrostatic attraction between cations and anions

Question 11

what is the evidence for ions?

Answer 11

Green copper chromate solution(aq) —> Cu+ (blue) moves to anion, Cr- (yellow) moves to cation

Question 12

Define a covalent bond

Answer 12

Strong electrostatic attraction between two nuclei and the shared pair of electrons between them. Occurs from the overlap of orbitals

Question 13

what is a molecule

Answer 13

uncharged group of two or more atoms held together

Question 14

what is dative covalent bond

Answer 14

A covalent bond formed when both electrons come from the same atom

Question 15

What are the 3 types of covalent substances?

Answer 15

-giant covalent e.g diamond
-simple covalent e.g Br2
-non-crystalline e.g polymers

Question 16

Shapes of molecules : BeCl2

Answer 16

-Linear
-Bond angle: 180

Question 17

Shapes of molecules: BCl3

Answer 17

-Trigonal planar
-bond angle: 120

Question 18

Shapes of molecules: CH4

Answer 18

-Tetrahedral
-bond angle: 109.5

Question 19

Shapes of molecules: PCl5

Answer 19

-Trigonal Bipyramidal
-bond angle: 120 and 90

Question 20

Shapes of molecules: SF6

Answer 20

-Octahedral
-bond angle: 90 and 180

Question 21

Shapes of molecules: H2O

Answer 21

-Bent
-bond angle: 104.5

Question 22

What is the theory for the explanation of the shape of molecules?

Answer 22

Valance electron shell repulsion theory (VESPR)

Question 23

Define Electronegativity

Answer 23

The ability of an atom’s nucleus to attract bonding electrons in a covalent bond

Question 24

how is the bond described in a covalent if the two elements have different electronegativity

Answer 24

the bond is polar

Question 25

How does electronegativity change across a period and down a group?

Answer 25

-Across a period: electronegativity increases (ionic character also increases) -Down a group: electronegativity decreases

Question 26

what happens if a molecule has polar bonds but is symmetrical?

Answer 26

The dipoles cancel each other out and the molecule is non-polar

Question 27

What are london forces?

Answer 27

An intermolecular force that acts between all covalent molecules which strength depends on the number of electrons in a molecule

Question 28

How are london forces formed?

Answer 28

Caused by the fleeting attractions and repulsions between the nuclei of an atom and surrounding clouds of electrons (Temporary instantaneous dipoles)

Question 29

What is the effect of larger molecules on London forces?

Answer 29

Larger molecules = more electrons = higher polarisability (extent of which electron clouds can be distorted by an electric charge) = greater possibility for temporary induced dipoles

Question 30

What are permanent dipole forces?

Answer 30

Occur between the partial “+” of one molecule and the partial “-“ of another molecule. Acts in addition with london forces

Question 31

What are Hydrogen Bonds?

Answer 31

Strongest intermolecular force. Occurs between the partial H+ charge on one molecule and that partial X- charge on another molecule.

Question 32

What is the bond angle around the hydrogen atom in a hydrogen bond?

Answer 32

180

Question 33

How does strong intermolecular forces affect Mp/Bp?

Answer 33

High(er) Mp/Bp

Question 34

Are most ionic compounds soluble in water?

Answer 34

Yes because energy is released in the attraction of the ionic compound’s anions and cations to the partially charged oxygen and hydrogen

Question 35

Are Hydrogen-bonded covalent molecules soluble in water?

Answer 35

Yes because they can form hydrogen bonds in the water

Question 36

Are covalent molecules with no hydrogen bonding soluble in water?

Answer 36

No but are soluble in organic solvents

Question 37

What is metallic bonding?

Answer 37

An attraction between the “sea” of delocalised electrons and the positive ions, which are fixed in a lattice

Question 38

Do group 1 metals have a low Mp/Bp and why?

Answer 38

Yes because they only have 1 valance electrons for delocalisation and the ions only carry a 1+ charge

Question 39

What does strength of a metallic bond depend on?

Answer 39

Strength depends on the number of valance electrons and the size of the metal ion; smaller ionic radii = stronger bond

Question 40

what does the mobility of delocalised electrons allow metals to do?

Answer 40

-Carry Charge -Malleable -Ductile

Question 41

What are the 3 main types of lattice?

Answer 41

-Ionic -Covalent -Metallic

Question 42

How are ionic solids arranged in a lattice?

Answer 42

The cations and anions are held together by strong electrostatic forces to form an ionic “crystal”

Question 43

How are Covalent lattices arranged?

Answer 43

Lattices are joined by strong covalent forces. The common allotropes: - Diamond -Each carbon has 4 sigma bonds forming a tetrahedral structure -Graphite -Each carbon bonded to 3 other carbons, 1 delocalised electron that can carry charge. Forms layers of hexagonal rings. Layers held by weak London forces

Question 44

What forces acts between Simple covalent substances?

Answer 44

Weak intermolecular forces

Question 45

What state do simple covalent molecules tend to be at room temperature?

Answer 45

Liquid or gas depending in the size of the covalent molecule which affects the strength of London Forces and therefore Mp/Bp

Question 46

What forces act between polar molecules?

Answer 46

London forces + Permanent dipole forces

Question 47

What bonds occur between organic acids and alcohols?

Answer 47

London Forces + Hydrogen bonds