S2.3 - The metallic model Flashcards
Define metallic bonding
The electrostatic attraction between cations and delocalised valence electrons (in a lattice structure)
What are the 6 typical properties of metals
• Lustere
• Sonority
• Malleability
• Ductility
• Electrical Conductivity
• Thermal Conductivity
Explain the trend between electrons conductivity and periods
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.
Why aren’t ionic compounds thermal conductors
Do not have free moving electrons
Why are metals malleable
• Layers of ions can slide past eachother
• Bonding remains unchanged
• Can be hammered into thin sheets
What type of bonding in ionic , metallic and covalent
Ionic and metallic - Non-directional
Covalent - directional
Describe the melting point in a polar covalent molecule
Low
What’s the difference between molecule and a lattice
lattice - large collection of atoms, ions or molecules in a highly ordered repeated pattern
molecule - discrete group of two or more atoms
What two factors affect the strength of the metallic bond
• radius of the metal cations
• ionic charge
The smaller the radius of the metal ion , the stronger the metallic bond.
Explain why
There is a shorter distance between the positive nucleus of the cation and the surrounding delocalised electrons , therefore stronger electrostatic attraction
Why do metals further down the group have a larger cationic radius
Due to the presence of an additional energy level
Why does lithium have the strongest metallic bond in the group
• 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
The higher the ionic charge , the stronger the metallic bond . Why ?
greater charge on the metal ion
greater number of delocalised valence electrons
Why does magnesium have a stronger metallic bond than sodium ?
• 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.
Why does the melting point decrease as you go down a group in the s block
Due to the decrease strength of the metallic bond as the radius of the metal ion increase (weaker electrostatic attraction)
What makes transition metals transition metals
partially filled d-sub shell
number of different oxidation states
Why is copper hard
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
Why has transition metals have high melting points and electrical conductivity
They have delocalised d electrons that strengthen the metallic bond by increasing electron density in the lattice
State the meaning of hybridisation
mixing of atomic orbitals to form new orbitals
How do you know if a species has delocalised electrons
• Double bonds
• can STILL display resonance
Explain formation of pi bonds
Sideways Overlap of p orbitals
Explain how metal’s conduct electricity
Bonding electrons are delocalised
able to flow throughout atom
Explain how metals are malleable
Can be hammered into thin sheets
atoms capable of slipping past eachother
Why are metals strong and hard
due to strong electrostatic forces between metal ions and delocalised electrons
Why are metals good thermal conductors
The delocalised electrons carry the increased kinetic energy and transfer it rapidly through the metal
why do metals have a strong melting and boiling point
due to strong electrostatic forces of attraction between the cations and delocalised electrons , requires large amounts of energy to move
What are the two factors affecting strength of the metal
The charge of the metal ion
The radius of the metal ion
Explain how the charge of the metal ion affects its strength
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
How does the radius of the metal ion affect the strength
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
Why does melting point decrease down a group
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
Definition of Transition Metals
An element with an incomplete d-sun shell that can form at least one stable cation with an incompleted d-subshell
Explain why transition metals have partially good electrical conductivity
3d and 4s sub shells are close in energy the transition metals are able to delocalise their d-electrons to form metallic bonds.
Why do transition metals have high mp
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
Trends in atomic radii
generally decreases across each period
Increase down a group
Why would there EVER be an increase in ionisation energy
electrons being removed from and increasingly positively charged ion
Why is Al first ionisation energy lower than magnesium
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.
