Structure & Bonding

Question 1

what does bonding mean/describe

Answer 1

how the electrons are distributed to make chemical bonds

Question 2

what do noble gases do/have

Answer 2

• a full outer shell
• do not need to bond
• exist as single atoms and all exist as gases at room temperature

Question 3

what is a covalent bond

Answer 3

the attraction between the positive nuclei and a shared pair of electrons

Question 4

bonding between individual molecules

Answer 4

is not covalent and is weak

Question 5

why do simple covalent molecules have low melting and boiling points

Answer 5

• attraction between molecules and are very weak

* easy to separate the molecules

Question 6

carbon exists in two forms / allotropes

Answer 6

diamond and graphite

Question 7

structure and bonding of diamond

Answer 7

covalent bond, giant molecular lattice structure

Question 8

bond of carbon as diamond

Answer 8

each carbon atom is covalently bonded to 4 other carbon atoms in a tetrahedral arrangement

Question 9

uses of diamond

Answer 9

• drill bits to cut through rocks

* jewellery

Question 10

why are large amounts of energy required to break diamond

Answer 10

• covalent bonds extend through the crystal in a lattice
• each diamond is a single giant molecule
• large numbers of strong covalent bonds

Question 11

graphite bonding and structure

Answer 11

covalent bond, layer lattice structure

Question 12

how are the carbon atoms bonded in graphite

Answer 12

carbon atoms bonded covalently to 3 other carbons within layers to form a hexagon of atoms.

Question 13

why is graphite soft and slippery

Answer 13

only weak intermolecular forces holding layers together so the layers of atoms can easily slide over eachother

Question 14

what can graphite conduct

Answer 14

electricity

Question 15

uses of graphite

Answer 15

lubricant, pencils, used as electrodes

Question 16

what is metallic bonding

Answer 16

attraction between a lattice of positive ions and a sea of delocalised electrons

Question 17

why are metals strong and have high melting points and boiling points

Answer 17

strong electrostatic attraction between positive ions and negative electrons means that a lot of energy is required to separate the particles from the lattice

Question 18

why are metals malleable

Answer 18

less energy is required to slide one layer of positive metal ions over another layer

Question 19

why are metals good conductors of electricity

Answer 19

if a potential difference is applied across a piece of metal, the electrons will move, carrying an electrical current

Question 20

what is an alloy

Answer 20

mixture of metals

Question 21

why are alloys stronger and harder than normal metal

Answer 21

always contain atoms of different sizes, which distorts regular arrangements of atoms. makes it more difficult to slide over eachother, so alloys are harder

Question 22

what is ionic bonding

Answer 22

where ions are held together by strong electrostatic attractions between oppositely charged ions

Question 23

why are there high b/m points in ionic bonds

Answer 23

strong electrostatic attractions

Question 24

conductivity in ionic bonds

Answer 24

• can only conduct when melted or dissolved when ions can move
• when solid they cannot move so cannot conduct

Question 25

why is carbon dioxide a gas at room temperature but silicon dioxide is a solid

Answer 25

• co2 has weak intermolecular forces between molecules

* sio2 is a giant molecular structure that only has strong covalent bonds that have to be broken

Question 26

why is diamond hard but granite soft

Answer 26

• diamond is a giant molecular lattice. has strong covalent bonds which are hard to break
• graphite is a layer latice. layers of atoms can slide over eachother

Question 27

what does structure mean/describe

Answer 27

it describes how the atoms, ions or molecules are arranged in a solid