Covalent Bonding

Question 1

What is a covalent molecular substance?

Answer 1

Molecules held together by covalent bonds, where the attraction between the molecules is weak and there are no charged particles.
Different elements are in the molecule.
eg Co2 gas

Question 2

What is a molecule?

Answer 2

Group of non metallic atoms held together by covalent bonds. Theyre combined in a fixed ratio and are neutral

Question 3

What is a covalent molecular element?

Answer 3

Identical atoms held together by covalent bonds- theyre discrete as theyre all seperate

Question 4

What is covalent bonding?

Answer 4

Bonding between non metals where they share pairs of electrons to get full outer shell.

Question 5

What is a covalent bond between?

Answer 5

Similtaneous attraction between two positive nuclei and the same shared pairs of electrons

Question 6

Outline VSEPR

Answer 6

The electron pairs in molecules repel each other and take up positions as far away from one another as possible.

Question 7

What does VSEPR stand for

Answer 7

Valence Shell Electron Pair Repulsion theory

Question 8

What are binary molecular compounds?

Answer 8

Compounds where there are only 2 elements in it

eg water c02 methane

Question 9

How do we name an molecular substance?

Answer 9

First ones named fully then second element names as an ide. Use prefix for the elements.
eg Carbon Di-oxide
Di hydrogen Oxide
Nitrogen Tri Bromide

Question 10

What is another definition for electronegativity?

Answer 10

Relative attraction that an atom has for shared electrons in a covalent bond.

Question 11

What are non polar covalent bonds?

Answer 11

Two atoms of same/equal electronegativity simaltaneously attract shared pairs of electrons

Question 12

What are polar covalent bonds?

Answer 12

Covalent bonds where the bonding electrons are unequally shared. Electrons are therefore unsymmetrically distributed

Question 13

what is a bond dipole?

Answer 13

In a polar covalent molecule one end becomes slightly more positive and one slightly more negative. this seperation is a bond dipole

Question 14

What level of difference in electronegativities causes each of the bonds?

Answer 14

0 up to 0.4= non polar
0.4 up to 2= polar
2 or more= ionic

Question 15

What is a polar molecule?

Answer 15

One end of the molecule is slightly positive and one end is slightly negative. Contains polar bonds and is
called a Dipole

Question 16

Whats a non polar molecule?

Answer 16

Molecule containing only non polar bonds

Question 17

What is the difference between intra and inter molecular bonding>

Answer 17

Intra-molecular bonding is inside molecules, so covalent bonds, and inter molecular bonding is between the molecules so dispersion etc.

Question 18

What is the purpose of intermolecular bonding?

Answer 18

Determines state of molecule usually

Question 19

What is the golden rule of intermolecular bonding?

Answer 19

The stronger it is the higher the b and m point of a substance.

Question 20

What are dispersion forces?

Answer 20

2 types

1. All electrons of an atom are attracted by all neighbouring nuclei.
2. Instantanous dipoles occur where at any time there’s a chance electrons could be on one side of an atom causing an induced dipole.

Question 21

Whats the problemo with dispersion forces?

Answer 21

For them to really have much of an effect, the atoms need to be slowed down and they’re pretty weak.

Question 22

What makes dispersion forces stronger?

Answer 22

1. Size of molecule. as it increases dispersion forces are stronger
2. Shape of molecule. The closer they can get the stronger the dispersion forces.

Question 23

What are dipole-dipole interactions?

Answer 23

If molecules are polar in a sample, the slightly oppositely charged ends attract each other .

Question 24

What is hydrogen bonding?

Answer 24

Special case of dipole dipole attractions
When hydrogen bonds to a more electronegative element the h nucleus is left unsheilded!!
only occurs with F O and N
Stronger than regular dipole dipole by far

Question 25

Why is hydrogen bonding to blame for waters properties? Name 3 properties and why

Answer 25

High melt and B points due to strong h bonds holding atoms together
Expands on freezing- Open hexagonal lattice of ice plates puts them further apart then in the liquid state.

Question 26

Ice forms layer on top that insulates the cooler water below. Why is this good?

Answer 26

fishies

Question 27

What is the general rule for solubility of molecular substances?

Answer 27

Like disolves like.

Polar water dissolves polar molecular substances for eg

Question 28

Do Molecular substances have high or low melting points? Why?

Answer 28

Low melting points, as intermolecular forces are weak. Most are gasses or liquids at room temp.