C2 BONDING, STRUCTURE AND THE PROPERTIES OF MATTER

Question 1

what is ionic bonding?

Answer 1

electrostatic attraction between positive and negative ion

Question 2

how are ionic compounds held together?

Answer 2

giant lattice
regular structure that extends in all directions in a substance

Question 3

properties of ionic compound?

Answer 3

high melting and boiling point
does not conduct electricity when solid (ions in fixed position)
conduct when molten or dissolved in water - ions are free to move

Question 4

how are ionic compounds formed? explain in terms of MgO case

Answer 4

reaction of a metal with a non metal
electron transfer occurs - metal gives away its outer shell electron to non-metals.
Mg is in group 2 so have two available outer shell electrons.
O is in group 6 and can accept 2 electrons on its outer shell electron to get full outer shell confiigurations.

mg becomes mg2+ and o becomes o2- (oxide)

Question 5

covalent bond?

Answer 5

shared pair of electrons between two atoms

Question 6

structure and properties of simple molecular covalent substances?

Answer 6

does not conduct electricity
small molecules
weak intermolecular forces
low melting and boiling point

Question 7

how do intermolecular forces change as the mass/size of the molecule increases?

Answer 7

they increase (that causes melting/boiling point to increase as well).
more energy is needed to overcome these forces

Question 8

polymers?

Answer 8

very large molecules with atoms linked by covalent bonds

Question 9

giant covalent substances?

Answer 9

solid , atoms covalently bonded together in a giant lattice.

high melting/boiling points - strong covalent bonds

mostly don’t conduct electricity (no delocalised e-)

e.gs - diamond, graphite, silicon dioxide

Question 10

describe and explain the property of diamond (allotropes of carbon) ?

Answer 10

four strong covalent bonds for each carbon atom
very hard
very high melting point
does not conduct electricity

Question 11

describe and explain the property of graphite(allotropes of carbon) ?

Answer 11

•3 covalent bonds for each carbon atom
•layers of hexagonal rings
•high melting point
•layers free to slide (weak intermolecular forces between layers; soft)
•can be used as lubricant
conduct thermal and electricity due to one delocalised electron per each carbon atoms

Question 12

describe and explain the property of fullerenes(allotropes of carbon) ?

Answer 12

hollow shaped molecule
based on hexagonal rings but may have 5-7 carbon rings
c60 has a spherical shape , simple molecular structure (buckministerfullerene)

Question 13

describe and explain the property of nanotubes (allotropes of carbon)

Answer 13

cylindrical fullerene with high length to diameter ratio
high intensile strength (strong bonds)
conductivity (deloc. electrons)

Question 14

describe and explain the property of graphene (allotropes of carbon)

Answer 14

a single layer of graphite

Question 15

metallic bonding?

Answer 15

forces of attraction between delocalised electrons and nuclei of metal ions

Question 16

alloys?

Answer 16

mixture of metals with other elements usually metals

Question 17

why are alloys harder then pure metals?

Answer 17

different sizes of atoms distorts the layers so they cant slide over eachother

Question 18

31

Answer 18

31

Question 19

what does the amount of energy needed to change state from solid to liquid or liquid to gas?

Answer 19

the strength of the forces between the particles of the substances.
the nature of particles involved depends on the type of bonding and the structure of the substance.
the stronger the forces between the particles the higher the melting point and boiling point of the substance

Question 20

a pure substance will melt or boil at

Answer 20

a fixed temperature

a mixture will melt over a range of temperatures

Question 21

3 states of matter?

Answer 21

solid , liquid , gas