3.1.3 Bonding

Question 1

3.1.3.4 What are the five types of structures?

Answer 1

Monatomic Crystals- Ionic, metallic, macromolecular (giant covalent) and molecular

Question 2

3.1.3.4 What is absolute zero?

Answer 2

The temp at which particles do not vibrate so have no kinetic heat energy. It is -273degrees Celsius which is 0 Kelvin

Question 3

3.1.3.4 How is Kelvin calculated?

Answer 3

degrees celsius + 273

Question 4

3.1.3.4 What is the relationship between temp and KE?

Answer 4

Temperature is directly proportional to the mean kinetic energy of the particles

Question 5

3.1.3.4 What is latent heat?

Answer 5

The energy required to change state w/o any change in temp (flat line on graph)

Question 6

3.1.3.4 What happens during condensation/solidifying?

Answer 6

Energy from forming forces/bonds is released as heat energy- exothermic. This stops the temp from falling further as the mean KE of the particles remains constant despite the state change

Question 7

3.1.3.4 What happens during melting/evaporating?

Answer 7

Heat energy is used to break bonds and surroundings will cool down as heat required for the reaction is absorbed- endothermic

Question 8

3.1.3.4 Why do liquids cool as they evaporate?

Answer 8

Some KE is used to overcome forces between the particles to allow to allow them to escape so the mean KE of the remaining particles is lower and so the temp is lower.

Question 9

.5 What is a bonding pair?

Answer 9

The two shared electrons in a covalent bond

Question 10

.5 What is a lone pair?

Answer 10

Two electrons in a pair not involved in bonding

Question 11

.5 What is the electron pair repulsion theory?

Answer 11

each pair of electrons around an atom will repel all other electron pairs, the pairs of electrons will therefore lake up positions as far apart as possible to minimise repulsion

Question 12

.5 What are the five basic shapes of molecules and their bond angles?

Answer 12

Linear (180), trigonal planar (120), tetrahedral(109.5), trigonal bipyramidal (120 and 90) and octahedral (90)

Question 13

.5 Why do lone pairs repel more than bonding pairs and effect on the bonding angle?

Answer 13

Because they are more compact than bonding pairs so repel more, reducing the bond angles by a small extent

Question 14

.5 How do you work out the shapes (molecules with single bonds only)?

Answer 14

1) Work out outer shell electrons around central atom 2)Work out number of bonding pairs (no. of atoms bonded to central atom)
3) Work out lone pairs- 1/2 diff between 1 and 2
4) Draw

Question 15

.5 Examples of linear structures

Answer 15

BeCl2

Question 16

.5 Examples of trigonal planar structures

Answer 16

ICl3, BH3

Question 17

.5 Example of tetrahedral structures

Answer 17

AlCl-, BeCl4-, CH4

Question 18

.5 Example of trigonal bipyramidal structure

Answer 18

PF5

Question 19

.5 Examples of octahedral structure

Answer 19

SF6

Question 20

.5 Shapes for 3 electron pairs

Answer 20

3 bonding pairs- Trigonal planar (120) 2bp 1lp bent(V-shape) (118degrees)

Question 21

.1 What is the formula for the compound ion Sulfate

Answer 21

SO4^2-

Question 22

.1 Formula for compound ion Nitrate

Answer 22

NO^3-

Question 23

.1 Formula for compound ion Hydroxide

Answer 23

OH-

Question 24

.1 Formula for compound ion Carbonate

Answer 24

CO3^2-

Question 25

.1 Formula for compound ion Ammonium

Answer 25

NH^4+

Question 26

Ionic Bonding/ Structures

Answer 26

Ionic bonding is the result of electrostatic attraction between oppositely charged ions, caused by the exchanging of electrons to form ions.
The attraction extends throughout the compound.
Every positive ion attracts every negative ion and vice versa.
Ionic electron transfer compounds always exist in a structure called a lattice

MP/BP: High- lots of energy required to overcome strong esf btw ions

EC: When dissolved/molten- ions free to move and carry a current

Strength: Hard and brittle- they form a lattice of alternating positive and negative ions, a blow in the direction shown may move the ions and produce contact between ions with like charges which then repel

Question 27

Metallic bonding/structure

Answer 27

A lattice of positive ions existing in a ‘sea’ of outer electrons. These electrons are delocalised
Greater charge, stronger attr forces as more electrons released into ‘sea’
Larger in size, weaker attr forces due to greater AR

MP/BP: High- strong esf btw +ve metal ions and -vely charged delocalised electrons

EC: When solid and molten- delocalised electrons free to move and carry a current

Strength: Malleable and ductile- ions/layers in lattice can slide over each other but are still held together by delocalised electrons

Solubility: Insoluble in water- Polarity of water molecs not large enough to overcome strong attractive forces (btw positive ions and negative electrons)