metals, ionic, covalent (m+n), carbon

Question 1

metallic bonding

Answer 1

chemical bonding that results from attraction between metal atoms and the surrounding sea of electrons

Question 2

why do metals have high MP and BP

Answer 2

forces of electrostatic attraction between metal cation and delocalised electrons are very strong so it requires more energy to break them

Question 3

why do metals conduct electricity

Answer 3

delocalised electrons are free to flow through the metal and so carry a current.

Question 4

why is metal malleable

Answer 4

bonding in metals is not rigid. as metals are metal with a force, the atoms slide through electron sea to new positions while continuing to maintain their connections to each other. this also makes the ductile.
attractive forces stronger than repulsive.
non directional bonding

Question 5

why are metals dense

Answer 5

particles are closely packed together

Question 6

why are metals shiny

Answer 6

freely moving and delocalised electrons are present so metals can reflect light and appear shiny.
close packing of cations prevent light from slipping through making it opaque

Question 7

what does a greater core charge about a metal mean in terms of bonding

Answer 7

atoms packed tightly with stronger bonds

Question 8

structure of metallic bonds

Answer 8

1. cations are closely packed in 3d network. cations occupy fixed positions in lattice
2. delocalised electrons moving freely. they belong to the lattice as a whole, not an individual atom
3. these electrons come from valence electrons not inner shell ones
4. cations held in position due to ESF of attraction between cations and electrons (metallic bonding)

Question 9

limitations to metallic bonding

Answer 9

structure can't explain:
variations in properties
magnetic nature
differences in electrical conductivities
*more complex model needed

Question 10

ways to modify metals

Answer 10

alloy production
heat treatment
formation of nanoparticles

Question 11

alloys

Answer 11

mixing metals with other substances (metal/carbon). substances are melted, mixed and cooled.

harder and lower MP: since atoms of different sizes are now included, the properties may differ. lattice doesn’t move in the same way (lower MP)

Question 12

iron + carbon

Answer 12

steel
harder and less corrosive, but less malleable because atoms are slightly different in size and lattice can’t move past each other as easily.

Question 13

ionic bonds

Answer 13

when a metal and non metal come into contact and a electron is lost from the metal and given to non metal. cations and anions formed. held together by electrostatic forces of attraction between ions (ionic bonding)

each cation is surrounded by anion and vice versa (attractive forces outweigh repulsive forces)

Question 14

why do ionic compounds have high MP and BP

Answer 14

large amount of thermal energy to overcome attraction between oppositely charged ions and allow them to move freely
bricks in furnace made of MgO

Question 15

why are ionic compounds brittle and hard

Answer 15

strong forces of electrostatic attraction hold ions together, so a strong force is required to break them
brick in houses CaPO4

when a force is applied ions move in the direction of the force, like ions are forced together causing them to repel (repulsion causes it to shatter)

Question 16

ionic compounds and electrical conductivity

Answer 16

solid: not free to move, can’t conduct current
ceramic insulators

solution/liquid: lattice dissociates in water into charged ions that move freely in solution
cations -> cathode
anions -> anode
ammonium chloride in dry cell batteries as electrolytes

Question 17

ionic compounds and solubility

Answer 17

soluble: ions break away and mix with water molecules
insoluble: ions remain bonded and don’t form a solution
depends on:
1. attraction between cation and anion
2. ion and water molecule

Question 18

why are metals good conductors of heat

Answer 18

cations vibrate vigorously and are able to transfer thermal energy to each other

Question 19

why do metals form cations

Answer 19

low ionisation energy

Question 20

interstitial alloys

Answer 20

when atoms of element that is supposed to be mixed with metal is much smaller and fill spaces between lattice

Question 21

substitutional alloy

Answer 21

larger, similar property metal added to lattice

Question 22

covalent molecular bonds

Answer 22

sharing of electrons to attain full valence shell. molecules are discrete (individual)
if atoms have similar electronegativities than they are like to form covalent bonds because they have the same affinity for electrons and don’t want to donate.

positively charged nuclei attracted to shared electrons

Question 23

low MP of covalent molecular

Answer 23

Intermolecular forces are weak so not much energy is required to break them

Question 24

non conductivity of covalent molecular

Answer 24

no mobile particles

electrons locked in covalent bonds

Question 25

softness of covalent molecular

Answer 25

intermolecular forces are weak
molecules can be moved out of position easily
hence soft

Question 26

covalent networks and properties

Answer 26

only intramolecular forces
made form network of repeating lattices of covalently bonded atoms (intramolecular)
eg silicon dioxide, carbon, silica
properties: 
hard
high MP + BP
solid @room temp
non conductive (except graphite)

Question 27

allotrope

Answer 27

different forms of an element
atoms bonded together in different specific ways
have slightly different properties

Question 28

diamond

carbon allotrope

Answer 28

hard -> not discrete in covalent network lattice
each carbon surrounded by 4 other carbon
high thermal conductivity because atoms are held together strongly

Question 29

graphite

carbon allotrope

Answer 29

slippery, soft, greasy
conductive (free moving electrons)
covalent layer lattice ( each carbon has 3 other carbons and 1 delocalised electron per carbon atom)
each sheet is slightly positive and pushes down electrons which means there is weak attraction.