Structure And Bonding

Question 1

What are the properties of ionic compounds?

Answer 1

. Form ginat ionic latices as the positively charged ions in it are attracted to the negatively charged ions with electrostatic forces of attraction
. Very high melting and boiling points because it takes alot of energy to overcome the strong electrostatic forces of attraction
Soluble in polar solvents such as water. The water surrounds the ion. This can overcome the electrostatic attractions between the ions making it able to dissolve. If charge on ions increase, solubility decreases because water molecule cant overcome the electrostatic forces of attraction
. Don’t conduct electricity when they are solid as they don’t have any free moving charged particles to conduct electricity. Can conduct electricity when molten

Question 2

What is a covalent bond?

Answer 2

Bond between non metals. Electrons are shared, in order to form the same electron structure as the nearest Noble gass

Question 3

What is a dative covelent bond?

Answer 3

When an atom in a covelent bond uses it lone pair of electrons to form a bond with another atom

Question 4

How is a dative bond displayed in a stick diagram

Answer 4

By an arrow

Question 5

What is needed In Order for a dative bond to form?

Answer 5

Available orbitals for the electrons to occupy - acceptor atom must be electron defficient

Question 6

What is similar between dative bonds and covelent bonds?

Answer 6

They both have the same bond enthalpy - strengh of bond

Question 7

What is electronegativity

Answer 7

The ability of an atom to attract the pair of electrons in a covalent bond. This is based on the electron pair and the nucleus of the atom in question,

Question 8

What happens to electronegativity as you move across a period?

Answer 8

It increases due to the positive charge in the atom increases due to the presence of more protons wich increases attraction between nucleus and pair of electrons in the bond. Also atomic radius decreases across a period so nuclues and electrons closer together, increasing attraction.

Question 9

What happens to electronegativity as you move down a group?

Answer 9

It decreases

Question 10

What is ment by a pure covelent bond?

Answer 10

When the elements in the bond are the same so they have the same electronegativity, so the electron pair in the bond lies midway between the 2 nuclei

Question 11

What is a dipole?

Answer 11

When the electron pair in a covelent bond is more closer to one atom than the other due to the atom it’s closer to having a greater electronegativity. This seperation of charge is called a dipole. For example, in hydrogen chloride, the electron pair is closer to the chlorine atom compared to the hydrogen atom as it is more electronegative

Question 12

How do you show if a bond is polar?

Answer 12

. Represented by a delta negative and a delta positive to show the charges. Delta means that the charge is small, because the electron pair has only shifted towards the more electronegative atom. Delta negative sign goes on the more electronegative atom.

Question 13

What is a dipole moment?

Answer 13

When a covalent bond has an overall polarity do to the presence of one polar bond

Question 14

When a covalent compound has 2 bond that are polar but the bonds point in opposit directions, what is the polarity of that bond?

Answer 14

It has no overall polarity as the dipoles cancle each other out

Question 15

When is a molecule non polar?

Answer 15

When a molecule has all polar bonds but the molecule is symmetrical in all directions, so the dipoles cancle each other out making the molecule non polar

Question 16

What happens when a covalent bond between 2 atoms have very similar polarities?

Answer 16

The bond is non polar

Question 17

What happens when a molecule contains a non polar bond and polar bonds?

Answer 17

The dipoles cannot cancle so the molecule is polar

Question 18

What are simple molecular substances?

Answer 18

Substances that consist of relatively small molecules and each molecule has a fixed number of atoms

Question 19

Why do simple molecular substances have relatively low boiling points?

Answer 19

Because the have weak intermolecular forces that are easily broken so they will easily be overcome. When we heat a simple. Mole ular substance, this causes the molecules to move faster. At a certain tempurature the molecular forces break, allowing the molecules to move away from eachother

Question 20

What are intermolecular forces? What are the diferent types?

Answer 20

A force that occurs between molecules. There are 3 types:
. Induced dipole dipole interactions (van der walls forces)
. Permanent dipole dipole interactions
. Hydrogen bonds

Question 21

What is an insentaneous dipole?

Answer 21

A non permanent dipole formed in an atom instantaneously due to random electron movement

Question 22

What is an induced dipole?

Answer 22

When an instantaneous dipole in an atom causes one side of the atom to be negatively charged, which repells the electrons in another atom. This causes electrons in that atom to shift to one side causing a dipole.

Question 23

What is a van der waal force?

Answer 23

A force of attraction that occurs between atoms with instantaneous and induced dipoles

Question 24

What are some properties of van der waal forces?

Answer 24

. They are weak and easily broken, weaker than covalent bond
. Caused by random electron movement, meaning every single atom and element experiences van der waal forces, even if they experience other forces too
. Strengh of and der wall forces depends on the number of electrons, the more electons there are, the stronger the van der waal force is

Question 25

When does permanent dipole dipole interactions occur?

Answer 25

When a compound with a permanent dipole meats another compound with a permanent dipole, this can cause attraction to occur between the 2. Only molecules with a permanent dipole can experice these forces

Question 26

What is hydrogen bonding and how does it occur?

Answer 26

Hydrogen bonding is when a hydrogen in another compound bonds with the lone pairs of another element that bonded to a hydrogen. This element is either fluorine, nitrogen or oxygen.

Question 27

Why is ice less dence than water?

Answer 27

This is because in water, molecules are moving constantly so something they are close together and sometime they are further apart and bonds are constantly being broken anf formed. As we cool water down, molecules more more slowly. As we reach freezing point of water, 0°C, molecules a range themselves into an ordered structure. This structure is ice, and is stabilised by the network of hydrogen bonds. In ice, water molecules are spread further apart than in water, making ice less dense.

Question 28

What is the ionic formula for ammonium

Answer 28

+ NH ⁴

Question 29

What is the ionic formula for carbonate

Answer 29

2- CO 3

Question 30

What is the ionic formula for hydroxide

Answer 30

OH-

Question 31

What is the ionic formula for nitrate

Answer 31

NO- ³

Question 32

What is the ionic formula for sulfate

Answer 32

3- SO 4

Question 33

What does the formula if a compound tell us

Answer 33

The ions that are in that compound

Question 34

Why is the overall charge if an ionic compound zero

Answer 34

Because the positively charged ions and the negatively charged ions cancle each other out

Question 35

What is a giant ionic lattice

Answer 35

It is a regular structure made up of ions. It is called giant as it is made up of the same basic unit repeated over and over again

Question 36

What are simple covalent compounds

Answer 36

Compounds that are made up of lots of individual molecules. The atoms are heald together by covalent bonds, but the molecules within compound are held together by intermolecular forces

Question 37

What is the melting and boiling of simple covalent compounds

Answer 37

Low

Question 38

What are giant covalent structures

Answer 38

They are a type of crystal structure. They have a huge network of covalently bonded atoms are are sometime called macromolecular structure.

Question 39

What is the structure of graphite

Answer 39

The graphite is made up of hexagonal layers. Thses layers are made uo of carbon atoms covelently bonded to 3 other carbon atoms. The 4th outer elctron of carbon is delocalised so the structure contains delocalised electrons. The hexagonal layers are bonded together by weak van der wall forces

Question 40

What are the properties of graphite

Answer 40

. It is soft and slippery and can be used as lubricants as the bonds between layers can be easily broken so layers slide over each other . Delocalised electrons can conduct electricity . Has a low density as layers are quite far apart to each other in graphite compared to the length of the covelent bonds, so it can be used to make strong, lightweight sports equipment . Insoluble as covelent bonds in layers are too difficult to break . Very high melting points as strong covelent bonds are difficult to break

Question 41

What is the structure of dimond

Answer 41

. Carbon atoms are covelently bonded to 4 covelent atoms not there are no delocalisd electrons . Atoms arrange themselves in a tetrahedral shape, this is called crystal lattice structure

Question 42

What are the properties of diamond

Answer 42

. Very high melting points due to multiple strong covelent bonds . Extremely hard, used in diamond tipped drills and saws . It is a good thermal conductor, as vibrations travel easily through the stiff lattice . Insoluble like graphite . Can't conduct electricity as has no free moving charged particles

Question 43

What do metal elements exsist as

Answer 43

Giant metallic lattice structures

Question 44

What is metallic bonding

Answer 44

. The outmost electrons of am atom are delicalised and free to move about the structure forming ions. Metallic bonding is when these positive ions are strongly attracted to the sea of delocalised electrons. They formula a lattice of closely packed postivr ions and sea of delocalised electrons

Question 45

What are the properties of metals

Answer 45

. High melting points due to strong electrostatic forces of attraction between metal ions and delocalised electrons . Malleable and ductile as metal ions can slide over each other due to not bonds holding specific ions together . Good thermal conductor as deloclised electrons can pass kinetic energy to each other . Good electrical conductor as has delocalised electrons that carry charge . Insoluble due to strength of metallic bonds