Bonding

Question 1

what is ionic bonding?

Answer 1

Ionic bonding is the electrostatic force of attraction between oppositely charged ions formed by electron transfer

Question 2

What do metal and non-metal atoms gain/lose?

Answer 2

• metal = lose electrons forming positive ions
• non-metal atoms gain electrons to form negative ions

Question 3

when is ionic bonding stronger and melting point higher?

Answer 3

When the ions are smaller and/or have higher charges.

Question 4

Ionic Radii and positive ions

Answer 4

• they are smaller compared to their atoms because they have one less shell of electrons and the ratio of protons to electrons has increased.
  -there is a greater net force of on remaining electrons holding them more closely.

Question 5

ionic radii and negative ions

Answer 5

• formed from groups 5-7
• The negative ion has more electrons than the corresponding atom but the same number of prtons.
  -so the oull of the nucelus is shared over more electrons and the attraction per electron is less, making ion bigger.

Question 6

ionic radius trend from N to Al

Answer 6

• increasing numbers of protons from N to F and then NA to AL
• but same number of electrons
• the effective nuclear attraction per electron therefore increases and ions get smaller

Question 7

what happens in the trend of ionic radii when going down the group

Answer 7

There will be more shells of electrons so increases down the group

Question 8

what is a covalent bond

Answer 8

shared pair of electrons

Question 9

What is a dative covalent bond

Answer 9

When the shared pair of electrons in the covalent bond come from only one of the bonding atoms.

Question 10

what would be the direction of the arrow in dative bonding

Answer 10

the direction of the arrow goes from the atom that is providing the lone pair to the atom that is deficient

Question 11

what is metallic bonding

Answer 11

The electrostatic force of attraction between positive metal ions and the delocalised electrons

Question 12

What are the three factors affecting strength of metallic bonding

Answer 12

1. number of protons/strength of nuclear attraction
   The more protons the stronger the bond
2. number of delocalised electrons per atom (outer shell e’s are delocalised)
   The more delocalised electrons the stronger the vond
3. size of ion
   the smaller the ion, the stronger the bond

Question 13

Why does Magnesium have a stronger metallic bonds than Na?

Answer 13

• higher melting point
• there are more electrons in outer shell that are released to the sea of electrons.
• The Mg ion is also smaller and has one more proton.
• therefore a stronger electrostatic attraction between the positive metal ions and the delocalised electrons and higher energy is needed to break bonds.

Question 14

definition, structure and examples of Ionic bonding

Answer 14

1. electrostatic force of attraction between oppositely charged ions
2. giant ionic lattice
3. sodium chloride/ Magnesium Oxide

Question 15

Def, structure and examples of covalent bonding

Answer 15

1. shared pair of electrons
2. simple molecular - with IMFs between
3. Iodine, Ice, Co2, water, methane

Question 16

Def, structure and examples of metallic bonding

Answer 16

1. electrostatic force of attraction between the metal positive ions and the delocalised electrons
2. Giant metallic lattice
3. Mg and Sodium (all metals)

Question 17

Why are the boiling and melting points of ionic high

Answer 17

• high because of giant lattice of ions with strong electrostatic forces between oppositely charged ions.

Question 18

what is the solubility in water of ionic bonds

Answer 18

generally good

Question 19

Conductivity of ionic

Answer 19

poor - ions cant move/ fixed in a lattice

Question 20

conductivity when molten- ionic

Answer 20

good - ions can move

Question 21

genereal description of ionic

Answer 21

crystalline solids

Question 22

why is the melting point and boiling points of simple molecular molecules low

Answer 22

-low because of weak intermolecular forces between molecules
- importsnt to specify type of IMF

Question 23

solubility of Simple molecular in water

Answer 23

generally poor

Question 24

conductivity when solid for simple molecular

Answer 24

poor - no ions to conduct and electrons are localised (fixed)

Question 25

Conductivity of simple molecular when molten

Answer 25

poor: no ions

Question 26

general description of SM

Answer 26

mostly gases and liquids

Question 27

why is the BP and MP of macromolecular molecules high?

Answer 27

- high because of many strong covalent bonds in macromolecular structure. -Take a lot of energy to break the many strong bonds

Question 28

solubility of macromolecular mols in water

Answer 28

insoluble

Question 29

conductivity of macromolecular mols when solid

Answer 29

-diamond and sand: poor because electrons can't move (localised) -Graphite: good as free delocalised electrons between layers

Question 30

conductivity when molten for macromoleculars

Answer 30

poor

Question 31

general description of macromolecular

Answer 31

solids

Question 32

Why is the BP and MP for metallic molecules high?

Answer 32

- high because strong electrostatic forces between positive ions and sea of delocalised electrons

Question 33

solubility in water for metallic bonding

Answer 33

insoluble

Question 34

conductivity of metallic when solid

Answer 34

Good: delocalised electrons can move through the structure

Question 35

conductivity when molten for metallic bonds

Answer 35

good

Question 36

general description of metallic bonding

Answer 36

- shiny metal -malleable - positive ions in the lattice are all identical. So planes of ions can slide easily over one another. - attractive forces in the lattice are the same whichever ions are adjacent

Question 37

How do you explain the shape of a molecule?

Answer 37

1. state number of bonding pairs and lone pairs of electrons 2. state that electrons pairs repel and try to get as dar apart as possible. 3. if there are no lone pairs state that the electron pairs repel equally 4. If there are lone pairs of electrons, then state that lone pairs repel more than bonding pairs. 5. state actual shape and bond angle

Question 38

define electronegativity

Answer 38

Electronegativity is the power of an atom to attract a lone pair of electrons in a covalent bond

Question 39

which elements are the most electronegative

Answer 39

F, O, N and CL F is the most

Question 40

whats the trend in electronegativity across a group

Answer 40

- increases - the number of protons increases and the atomic radius decreases because the electrons in the same shell are pulled in more

Question 41

whats the trend in electronegativity down a group

Answer 41

- decreases - the distance between the nucleus and the outer electrons increases and the shielding of inner shell electrons inc.

Question 42

what does it mean when compounds contain elements of similar electronegativity

Answer 42

- small electronegativity diff - will be purely covalent

Question 43

what does it mean when compounds contain elements of different electronegativity

Answer 43

- large difference - will be ionic.

Question 44

How do permanent dipoles form?

Answer 44

- when elements in the bond have different electronegatives. - when a bond is a polar covalent it has an unequal distribution of electrons in the bond and produces a charge seperation, delta negative and positive ends.

Question 45

what is a symmetric molecule?

Answer 45

- all bonds identical and no. lone pairs. - it will not be polar even if individual bonds within molecular are polar.

Question 46

what do the individual dipoles on the bonds do?

Answer 46

they cancel out due to the symmetrical shape. There is no net dipole moment.

Question 47

What are van der waal forces?

Answer 47

They occur between simple covalent mols and seperate atoms in noble gases. in any molecules the e's are mpoving constatnly and radnomly: parts of the molecule can become more or less negative due to flunctuatioj in electron density.

Question 48

what do instantaneous dipoles do?

Answer 48

cause dipoles to form in neighbouring molecules. : induced dipoles They are always the opposite sign to the og one. forms between the delta pve i one mol and the delta - in a neighbouring mol

Question 49

What is the main factor affecting size of VDW

Answer 49

The more e's there are in the molecule the higher the chance that temporary dipoles will form. so Van Der Waals are stronger between molecules so BP is higher.

Question 50

Why do BP down group 7 increase?

Answer 50

- inc no of e's in bigger mols - causes inc in size of VDW

Question 51

Why do BP of alkanes increase?

Answer 51

- inc no of e's in bigger molecules - causing increase in size of VDW

Question 52

How does the shape of the mol have an effect on the size of VDW?

Answer 52

- long chain alkanes have a larger SA of contact between mols of VDW to form than compared to spherical shapes branched alkanes and so have stronger VDW.

Question 53

Properties of permanent DPDP forces

Answer 53

1. they are permenent dipole-dipolee forces which occur between polar molecules 2. stronger than VDW = higher BP 3. Polar have permanent dipoles 4. polar mols are asymmetrical - have a bond which has a significant difference in electronegativity between atoms

Question 54

What is Hydrogen bonding?

Answer 54

- occurs in compounds that have a hydrogen atom attatchd to N,O, or F. There is a large electronegativity difference between the H and the NOF.

Question 55

What do you need to do when drawing hydrogen bonding?

Answer 55

always show lone pair of electrons on the NOF and the dipoles and all the charges.

Question 56

what causes the high boiling points in hydrogen bonding?

Answer 56

caused by increasing van der waal forces between molecules due to an inc no of e's