S2.3 - The metallic model

Question 1

Define metallic bonding

Answer 1

The electrostatic attraction between cations and delocalised valence electrons (in a lattice structure)

Question 2

What are the 6 typical properties of metals

Answer 2

• Lustere
• Sonority
• Malleability
• Ductility
• Electrical Conductivity
• Thermal Conductivity

Question 3

Explain the trend between electrons conductivity and periods

Answer 3

As the number of valence electrons increases , the number of delocalised electrons moving throughout the lattice structure increases. This increases the electrical conductivity of the metal.

Question 4

Why aren’t ionic compounds thermal conductors

Answer 4

Do not have free moving electrons

Question 5

Why are metals malleable

Answer 5

• Layers of ions can slide past eachother
• Bonding remains unchanged
• Can be hammered into thin sheets

Question 6

What type of bonding in ionic , metallic and covalent

Answer 6

Ionic and metallic - Non-directional
Covalent - directional

Question 7

Describe the melting point in a polar covalent molecule

Answer 7

Low

Question 8

What’s the difference between molecule and a lattice

Answer 8

lattice - large collection of atoms, ions or molecules in a highly ordered repeated pattern

molecule - discrete group of two or more atoms

Question 9

What two factors affect the strength of the metallic bond

Answer 9

• radius of the metal cations
• ionic charge

Question 10

The smaller the radius of the metal ion , the stronger the metallic bond.

Explain why

Answer 10

There is a shorter distance between the positive nucleus of the cation and the surrounding delocalised electrons , therefore stronger electrostatic attraction

Question 11

Why do metals further down the group have a larger cationic radius

Answer 11

Due to the presence of an additional energy level

Question 12

Why does lithium have the strongest metallic bond in the group

Answer 12

• Lithium metal ions have a smaller radius , the lithium nucleus will be closer to the delocalised electrons , than the other group 1 metals and will result in a greater electrostatic attraction

Question 13

The higher the ionic charge , the stronger the metallic bond . Why ?

Answer 13

greater charge on the metal ion
greater number of delocalised valence electrons

Question 14

Why does magnesium have a stronger metallic bond than sodium ?

Answer 14

• Ionic radius will be similar, same number of occupied energy levels

• Magnesium has a 2+ charge , it will have a greater number of electrons making up the surrounding delocalised electrons, than sodium. The greater charge difference increase the strength of the electrostatic attraction between metal ions and delocalised electrons.

Question 15

Why does the melting point decrease as you go down a group in the s block

Answer 15

Due to the decrease strength of the metallic bond as the radius of the metal ion increase (weaker electrostatic attraction)

Question 16

What makes transition metals transition metals

Answer 16

partially filled d-sub shell
number of different oxidation states

Question 17

Why is copper hard

Answer 17

Copper has both 4s and 3d electrons and delocalised valence electrons , there is an increased attraction between these and electrons and the metal ions in the lattice. Increased strength of metallic bond results in greater hardness

Question 18

Why has transition metals have high melting points and electrical conductivity

Answer 18

They have delocalised d electrons that strengthen the metallic bond by increasing electron density in the lattice

Question 19

State the meaning of hybridisation

Answer 19

mixing of atomic orbitals to form new orbitals

Question 20

How do you know if a species has delocalised electrons

Answer 20

• Double bonds
• can STILL display resonance

Question 21

Explain formation of pi bonds

Answer 21

Sideways Overlap of p orbitals

Question 22

Explain how metal’s conduct electricity

Answer 22

Bonding electrons are delocalised
able to flow throughout atom

Question 23

Explain how metals are malleable

Answer 23

Can be hammered into thin sheets
atoms capable of slipping past eachother

Question 24

Why are metals strong and hard

Answer 24

due to strong electrostatic forces between metal ions and delocalised electrons

Question 25

Why are metals good thermal conductors

Answer 25

The delocalised electrons carry the increased kinetic energy and transfer it rapidly through the metal

Question 26

why do metals have a strong melting and boiling point

Answer 26

due to strong electrostatic forces of attraction between the cations and delocalised electrons , requires large amounts of energy to move

Question 27

What are the two factors affecting strength of the metal

Answer 27

The charge of the metal ion The radius of the metal ion

Question 28

Explain how the charge of the metal ion affects its strength

Answer 28

The greater the charge the greater the number of protons in the sea of delocalised electrons and the greater the charge difference between the ions and the electrons a greater charge difference leads to a stronger electrostatic attraction therefore a stronger metallicbond

Question 29

How does the radius of the metal ion affect the strength

Answer 29

metals with smaller atomic radii exert a. greater attraction on the sea of delocalised electrons The greater the attraction means stronger metallic bond requiring more energy to break

Question 30

Why does melting point decrease down a group

Answer 30

As you go down , the size of the cation increases this decreases the attraction between the outer electrons and metallic lattice reduction in melting point

Question 31

Definition of Transition Metals

Answer 31

An element with an incomplete d-sun shell that can form at least one stable cation with an incompleted d-subshell

Question 32

Explain why transition metals have partially good electrical conductivity

Answer 32

3d and 4s sub shells are close in energy the transition metals are able to delocalise their d-electrons to form metallic bonds.

Question 33

Why do transition metals have high mp

Answer 33

They have greater electron density (ability to delocalise the d-electrons) electrostatic attraction between the large positive charge of the cations and the sea of delocalised electrons are strengthened. Results in higher melting point, more energy is required to overcome them

Question 34

Trends in atomic radii

Answer 34

generally decreases across each period Increase down a group

Question 35

Why would there EVER be an increase in ionisation energy

Answer 35

electrons being removed from and increasingly positively charged ion

Question 36

Why is Al first ionisation energy lower than magnesium

Answer 36

Aluminium has one more electron shell than magnesium. The additional electron shell shield the outer electrons from the attraction of the nucleus making it easier to remove an electron from aluminium.