Unit 1 Structure And Bonding

Question 1

What are the two main categories of bonding?

Answer 1

Intramolecular
The bonding that occurs between atoms

Intermolecular
The bonding that occurs between molecules

Question 2

What are the 3 types of intramolecular bonds?

Answer 2

Pure covalent(non polar)
Polar covelent
Ionic

Question 3

What are covalent bonds?

Answer 3

Are shared pair of electrons electrostatically attracted to both positive nucli

Question 4

What are pure(non polar) covalent bonds?

Answer 4

Diatomic elements
Exist between atoms of same electronegativity, these electrons are shared evenly and the molecule has no ionic character

Question 5

How do polar covalent bonds form?

Answer 5

When 2 atoms share a pair of electrons unequally
They have difference in electronegativity

Question 6

What happens in a polar covalent bond, what is created?

Answer 6

The atom with the highest electronegativity becomes partially negative(symbol)
The atom with the lowest electronegativity becomes partially positive(symbol)

Dipole

Question 7

What are polar covalent bonds known as?

Answer 7

Dipoles

Question 8

When do ionic bonds form?

Answer 8

When electrons are transferred from one atom to another resulting in formation of ions

Large difference in electronegativity

Question 9

What happens to atoms and how is bond held in ionic?

Answer 9

The atom with lowest electronegativity forms a positive ion
The atom with highest electronegativity forms negative ion

The bond is formed due to the electrostatic attraction between the positive and negative ions

Question 10

What are ionic bonds between?

Answer 10

Non metal + metal

Question 11

What happens to metal and non metal atoms?

Answer 11

Metal atoms forms positive ions when they lose electrons as they have lower electronegatives

Non metal forms negative ions when they gain electrons as they have higher electronegatives

Question 12

What is bonding continuum?

Answer 12

Purecovalent->Polarcovalent->ionic

Pure covalent bonding and ionic bonding can be considered as being opposite ends of the bonding continuum

Question 13

What are the cut off for difference in electronegatives for non polar,polar and ionic?

Answer 13

<0.5 non polar
0.5-1.8 polar
>1.8 ionic

Question 14

What are the types of intermolecular bonds, what are they known as?

Answer 14

Van der waals forces

London dispersion forces
Pd-pd
Hydrogen bonding

Question 15

What is the weakest intermolecular forces and how do they arise?

Answer 15

They exist between all atoms and molecules
Formed as a result of electrostatic attraction between temporary dipoles and induced dipoles caused by movement of electrons in atoms/molecules

Question 16

What affects the strength of LDF forces?

Answer 16

The size of the molecule

Larger atoms and molecules have more electrons. This leads to larger dipoles being established

Question 17

What are pd-pd intercations?

Answer 17

Molecules w permanent dipoles are polar(contains polar bonds)
Interrcation occurs when a partially negative charge in one molecule is attracted to partially positive charge of another

Question 18

Why is water polar but carbon tetrachloride is non polar despite both containing polar bonds?

Answer 18

A substance that contains polar covenant bonds may not be overall due to symmetry

Water is angular=polar

Crabon… is tetrahedral so charges are symmetrical=non polar

Question 19

What is the strongest intermolecular bond

Answer 19

Hydrogen bonding

Question 20

What is needed for hydrogen bonding to occur?

Answer 20

When H atom is covalently bonded to a highly electronegative element(nitrogen,oxygen,fluorine)

Question 21

What happens to hydrogen when it is bonded?

Answer 21

H becomes partially positive, atoms becomes partially negative
Positive h is electrosaticalky attracted to partial negative atom in another molecule

Question 22

What happens to atoms of different intermolecular bonding for mp/bp?

Answer 22

The stronger intermolecular bonds(h bonding) more negery required to break bond and increased mo/bp