structure and bonding

Question 1

a covalent bond is…

Answer 1

two positive nuclei being held together by their common attraction for a shared pair of electrons.

Question 2

polar covalent bonds are formed when…

Answer 2

the attraction of the atoms for the pair of bonding electrons is different. delta positive and delta negative notation is used to indicate the partial changes on atoms, which give rise to a dipole.

Question 3

how to tell how polar a bond will be

Answer 3

the difference between the electronegativities between the bonded atoms

Question 4

ionic bonding is the…

Answer 4

electrostatic attraction between positive and negative ions.

Question 5

london dispersion forces are…

Answer 5

1. formed as a result of electrostatic attraction between temporary dipoles and induced dipoles caused by the temporary dipole repelling the electrons of a neutral atom pushing them to the other side of the atom.
2. forces of attraction that operate between all atoms and molecules.

Question 6

the strength of a london dispersion force is related to…

Answer 6

the number of electrons within an atom or molecule.

Question 7

diatomic molecules

Answer 7

FIBNOCH

Question 8

what is an intra molecular force ?

Answer 8

an attractive force that acts between the atoms within the molecule

Question 9

what is an inter molecular force ?

Answer 9

forces of attraction that act between the molecules

Question 10

why does fullerene have a high mp/bp?

Answer 10

because there are a large number of carbon atoms in each molecule;e meaning a large number of electrons resulting in an increase in the strength of the ldfs between molecules.

Question 11

describe fullerene

Answer 11

1. covalent molecule
2. high mp and bp for a covalent molecule
3. contains only ldfs that are strong due to the sheer number of carbon atoms (meaning there are more electrons and thus stronger ldfs.)

Question 12

describe diamond

Answer 12

1. covalent network structure
2. high mp and bp due to the face that there is a great amount of energy required to break the covalent bonds that hold the atoms together

Question 13

describe graphite

Answer 13

1. covalent network
2. lower mp and bp than diamond because the carbon atoms on each layer are held together by covalent bonds but the layers are held together by weak ldfs.

Question 14

why does graphite conduct electricity ?

Answer 14

because each carbon within the structure is only bonded to three other carbon molecules, one outermost electron on each carbon atom is not used to make covalent bonds (delocalised.)

Question 15

describe metallic bonding

Answer 15

a lattice of positive ions with delocalised electrons

Question 16

what is hydrogen bonding ?

Answer 16

bonds consisting of a hydrogen atom bonded to an atom of a strongly electronegative element (FON)

Question 17

what is a pure covalent bond

Answer 17

when both atoms involved in covalent bonding are the same or experience the same attractive force from each nuclei as the electronegativities are the same

Question 18

if the elements within a structure, of the same electronegativity, act in opposite directions from the central element (e.g, in linear, tetrahedral, and angular compounds)…

Answer 18

the structures can be non polar but the BONDS can be polar

Question 19

what are pdpds?

Answer 19

intermolecular forces of attraction between molecules that have a permanent overall dipole

Question 20

what can be said about the solubility of two substances that share similar intermolecular forces?

Answer 20

very soluable/ miscible ((in case of liquids))

Question 21

what can be said about the solubility of molecules within a structure that have very different intermolecular forces??

Answer 21

immiscible

Question 22

what is viscosity ?

Answer 22

a measure of how much the molecules in a compound stick together.

Question 23

what type of substances dissolve in water and why?

Answer 23

polar substances dissolve in water as water is also polar- particularly substances with hydrogen bonding.