📚🔥Chemistry 1.4 -bonding

Question 1

Define an Ionic Bond

Answer 1

A bond formed by the electrostatic attraction between positive and negative ions (actions and anions)

Question 2

Define a Covalent bond

Answer 2

Has a pair of electrons with opposed spin shared between two atoms with each atom giving one electron

Question 3

Define a co-ordinate bond

Answer 3

A covalent bond in which both electrons come from one of the atoms

Question 4

Give an example of a covalent bond

Answer 4

A bond between two non metals e.g CL2

Question 5

Give an example of an ionic bond

Answer 5

A bond between a metal and non metal for example Na + Cl —> NaCl

Question 6

What happens to the electrons shared in a covalent bond?

Answer 6

the electrons repel each other but this is overcome by their attraction to both nuclei

Question 7

What must be so that covalent bonds form?

Answer 7

The electrons spins must be opposite for the bonds to form

Question 8

How are ions arranged in ionic bonding to minimise repulsion

Answer 8

In ionic bonding cations and anions are arranged so that each cation is surrounded by anions and vica Verda to maximise attraction and minimise repulsion

Question 9

Describe a metallic bond

Answer 9

A lattice of positive ions held together by a ‘sea’ of delocalised electrons given up by each atom

Question 10

Describe the electro negativity in a covalent bond

Answer 10

The electron pair is not shared evenly between atoms, one will have a slightly greater electronegativity than the other forming a slightly polar bond

Question 11

Why are co-ordinate bonds always polar?

Answer 11

Because the atom giving both electrons can’t loose both its rights

Question 12

Define intermolecular bonding?

Answer 12

The bonding between molecule

Question 13

Define an intramolecular bond

Answer 13

Bonding within molecules

Question 14

Name 2 properties of intermolecular bonding:

Answer 14

• Low melting/boiling point

- bonding within molecules is strong and generally govern chemical reactivity

Question 15

What causes intermolecular bonding

Answer 15

It is caused by electrical attraction between opposite charges

Question 16

Explain how neutral molecule may be a dipole (e.g H20)

Answer 16

Because it contains bonds that may have a difference in electronegativity and therefore the molecule will be dipole

Question 17

Name a example of a molecules with non dipole show intermolecular bonding

Answer 17

Helium atoms come together to form a liquid at 4K

Question 18

Explain why molecules with no overall charge experience intermolecular bonding

Answer 18

Because the electrons are in constant motion around the nuclei so the centre of ‘+’ and ‘-‘ charge don’t balance producing a fluctuating dipole

Question 19

Explain how one He molecule would bond to another via intermolecular bonding

Answer 19

The fluctuating dipole induces am opposite dipole in a nearby molecule creating attraction

Question 20

Explain van der Waals forces

Answer 20

1. Electrons in atoms are moving around at any point so they are unlikely to spread evenly
2. This gives a molecule a temporary dipole
3. The dipole moment indices a temporary dipole in a neighbouring molecule/atom by attracting its electron charge cloud
4. These small induced dipole attract one another creating weak intermolecular forces know as van der Waals forces

Question 21

What kind of bonding is present in hydrogen bonding?

What elements is hydrogen bonding most likely to occur with?

Answer 21

Strong dipole-dipole interaction between H atom, one a very electronegative element having lone pairs namely fluorine, oxygen and nitrogen

Question 22

Which bonding is stronger hydrogen bonding or van der Waals?

Answer 22

Hydrogen bonding is much stronger than van der Waals forces

Question 23

What structure does ice have?

Answer 23

An open lattice with hydrogen bonds holding water molecules apart

Question 24

What happens to the bonding when ice melts?

Answer 24

When ice melts the rigid hydrogen bonds collapse allowing the water molecules to move closer together

Question 25

What is the effect of increased temperature on van der Waals forces?

Answer 25

As the strength of the intermolecular force increases boiling and melting point of a temperature also increases

Question 26

What happened to the boiling point of a van der Waals force as molecular mass and dipole increases

Answer 26

As the molecular mass / dipole increases the boiling point also increases

Question 27

Explain why water has an unusually high boiling point compared to the rest of group 6

Answer 27

Water has free hydrogen bonds which are very strong intermolecular forces, this means that a greater value of KE is needed to break such bonds increasing its boiling temperature to 100 degrees

Question 28

Why are polar molecules soluble?

Answer 28

Because they have a difference in electronegativity meaning the molecules can attract water molecules forming hydrogen bonds

Question 29

Why are non polar molecules insolvable?

Answer 29

No difference in electronegativity and therefore no overall charge meaning the molecule does not interact with the water molecule

Question 30

What bond is present if there is a large difference in electronegativity?

Answer 30

Ionic bonding

Question 31

What bond is present if there is a small difference in electronegativity?

Answer 31

Polar covalent bond

Question 32

Summarise the main features of an ionic bond:

Answer 32

• complete transfer of electrons

- metal + non metal

Question 33

Summarise the main features of a pure covalent bond:

Answer 33

• equal sharing of electrons
• no charge
• 2 identical non metals e.g H-H bond

Question 34

Name the two stages that fall between pure ionic and pure covalent bonding

Answer 34

• polar ionic (unequal sharing or electrons, partial ionic charges, 2 different non metals)
• polar covalent

Question 35

What does VSEPE theory stand for?

Answer 35

Valence Shell Electron Pair Repulsion

Question 36

Define VSEPR theory

Answer 36

“Bonding and lone pros know the outer shell of an atom will repel each other and take up position as far apart as possible”

Question 37

Why do lone pairs and bonding pairs repel each other?

Answer 37

Lone pairs of electrons are closer to the centre of the atom then bonding pairs, since they occupy a smaller volume the charge density is higher meaning that the lone pairs repel more strongly than the bonding pairs reducing the bond angle

Question 38

Name the shape which features at 90 degrees, it’s value of electron clouds and lone pairs

Answer 38

Octahedral, 6 electron clouds and 0 lone Pairs

Question 39

Name the shape which features at 105 degrees, it’s value of electron clouds and lone pairs

Answer 39

Non linear, 4 electron clouds and 2 lone pairs

Question 40

Name the shape which features at 107 degrees, it’s value of electron clouds and lone pairs

Answer 40

Pyramidal, 4 electron clouds and 1 lone pair

Question 41

Name the shape which features at 109.5 degrees, it’s value of electron clouds and lone pairs

Answer 41

Tetrahedral, 4 electron clouds and 0 lone pairs

Question 42

Name the shape which features at 120 degrees, it’s value of electron clouds and lone pairs

Answer 42

Trigonal Planer, 3 electron clouds and 0 lone pairs

Question 43

Name the shape which features at 180 degrees, it’s value of electron clouds and lone pairs

Answer 43

Linear, 2 electron clouds and 0 lone pairs

Question 44

Name the VSEPR repulsion sequence

Answer 44

Lone pair-lone pair > lone pair-bond pair > bonded pair- bonded pair

Question 45

What happens to the bond angle if there are no lone pairs

Answer 45

The bonding pairs will repel each other equally compressing the angle

Question 46

What happens if there are lone pairs and bonding pairs

Answer 46

The lone pairs will repel the bonding pairs strongly which compresses the bond angle