Topic 2 - Bonding & Structure

Question 1

How are ions formed?

Answer 1

when electrons are transferred from one atom to another

Question 2

What are simple ions?

Answer 2

Ions which have either lost or gained 1,2,3 electrons so they have a full outer shell

Question 3

what do all elements in the same group have?

Answer 3

same number of outer electrons

Question 4

What is an ionic bond?

Answer 4

it is the strong electrostatic attraction between two oppositely charged ions

Question 5

What is electrostatic attraction?

Answer 5

it holds positive and negative ions together- it’s very strong

Question 6

How do you get an ionic compound?

Answer 6

When oppositely charged ions form an ionic bond.
The total charge is 0

Question 7

Two things that affects the strength of an ionic bond?

Answer 7

1. Ionic charges-
   greater the charge=stronger ionic bond=higher melting/boiling point
2. Small closely packed ions - stronger ionic bonding

Question 8

what is an isoelectronic ion

Answer 8

ions of a different atom with the same number of electrons

(explains why atomic radius decreases across a period)

Question 9

What is the structure of an ionic compound ?

Answer 9

giant ionic lattice

Question 10

What are the physical properties of ionic bonding and explain them (4)

Answer 10

high melting point - ions held together by strong attraction

soluble in water but not non-polar - as particle are charged

don’t conduct electricity when solid - particles in fixed position ( when molten or dissolved particles free to move and carry charge )

brittle - trying to pull layers over each other create strong repulsion between same charge ions

Question 11

Describe an experiment that gives evidence for the presence of charged particles

Answer 11

electrolyse green solution of copper (II) chromate (VI) on piece of wet filter paper

paper turns blue at cathode (negative electrode) - positive copper ions = blue

paper turns yellow at anode (positive electrode) - negative chromate ions = yellow

Question 12

what is a covalent bond

Answer 12

the strong electrostatic attraction between a shared pair of electrons and two positive nuclei

Question 13

what is ionic bonding

Answer 13

the bonds between a two oppositely charged ions

Question 14

What does there need to be a balance of in a covalent bond

Answer 14

the attraction from the positive nuclei to the shared pair of electrons and the repulsion between the nuclei

Question 15

what is bond length

Answer 15

the distance between the two nuclei in a covalent bond

Question 16

what affects bond length

Answer 16

electron density - the higher it is, the higher the bond enthalpy and shorter the bond length

Question 17

what is a dative covalent bond

Answer 17

one atom donates both electrons to a bond

Question 18

how is a dative covalent shown (if not by the same dot/cross)

Answer 18

an arrow pointing away from ‘donor’ atom

Question 19

what is the order of the strength electron pair repulsion

Answer 19

lone pair - lone pair

lone pair - bond pair

bond pair - bond pair

Question 20

what is the shape of a molecule with 2 electron pairs around central atom (include name and bond angles)

Answer 20

linear molecules
180°

Question 21

what is the shape of a molecule with 3 electron pairs around central atom (include name and bond angles)

Answer 21

1. 3 bonding, 0 lone
   trigonal planar
   120°
2. 2 bonding, 1 lone
   bent
   119°

Question 22

what is the shape of a molecule with 4 electron pairs around central atom (include name and bond angles)

Answer 22

1. 4 bonding, 0 lone
   tetrahedral
   109.5°
2. 3 bonding, 1 lone
   trigonal pyramidal
   107°
3. 2 bonding, 2 lone
   bent
   104.5°

Question 23

what is the shape of a molecule with 5 electron pairs around central atom (include name and bond angles)

Answer 23

1. 5 bonding, 0 lone
   trigonal bipyramidal
   90° 120°
2. 4 bonding, 1 lone
   seesaw
   87° 102°
3. 3 bonding, 2 lone
   distorted T
   87.5°

Question 24

what is the shape of a molecule with 6 electron pairs around central atom (include name and bond angles)

Answer 24

1. 6 bonding, 0 lone
   octahedral
   90°
2. 5 bonding, 1 lone
   square pyramidal
   90° 81.9°
3. 4 bonding, 2 lone
   90°

Question 25

Why do metal have a giant structure?

Answer 25

1.Metals have delocalised electrons which makes them positive metal ion
2. Positive metal ions are electrostatically attracted to the delocalised electrons
3.layers of positive metal ions separated by layers of electrons

Question 26

describe the structure and properties of graphite

Answer 26

each carbon bonded to 3 other carbons - layers of hexagonal rings

no covalent bond between layers and weak intermolecular forces

soft

slippery

can conduct electricity as one electron from each carbon atom is delocalised

Question 27

describe the structure and properties of graphene (5)

Answer 27

one layer of graphite

conduct electricity

incredibly strong

transparent

light weight

Question 28

what are the uses of graphite

Answer 28

electrode
lubricant

Question 29

what are the uses of diamond

Answer 29

cutting tools

Question 30

Are melting points of metals generally high or low and why?

Answer 30

-High because of strong metallic bonding

-More electrons strengthen the metallic bonding, which would make the melting point increase