Periodicity Flashcards
(20 cards)
What is periodicity?
Repeating trends of physical or chemical properties
What is the trend in atomic radius down a group? Why?
Increasing Atomic Radius
Increase in number of principal energy levels
Therefore an increase in shielding
Outer electron is further from nucleus
What is the trend in atomic radius across a period? Why?
Decreasing Atomic Radius
Number of protons increases
Shielding is constant
Electrons are more strongly attracted to the nucleus and atomic radius decreases
Define first ionisation energy
The energy required to remove 1 mole of electrons from 1 mole of gaseous atoms
Describe the trend in first ionisation energy down a group. Why?
Ionisation Energy decreases
The electron is removed from a higher principal energy level
The electron is further from the nucleus There is more shielding
Weaker attraction between nucleus and outer electron
Describe the trend in first ionisation energy across a period. Why?
Ionisation Energy decreases
Number of protons increase
Shielding is constant/atomic radius decreases
Stronger attraction between nucleus and outer electron
Describe the trend in successive ionisation energies. Why?
Ionisation Energy increases
The positive charge on the ion increases
Ionic radius decreases
Nuclear attraction on the outer electron increases
Describe the first ionisation energy of a Group 3 element. Why?
Ionisation Energy decreases
The electron is removed from a higher energy p sub-level
Weaker attraction between nucleus and outer electron
Describe the first ionisation energy of a Group 6 element
Ionisation Energy decreases
There is a pair of electrons in a p orbital
Extra repulsion means less energy is required to remove the electron
Define metallic bonding
Strong electrostatic attraction between positive ions and delocalised electrons
What factors affect the strength of a metallic bond?
The ionic charge on the metal
The number of delocalised electrons
The ionic radius
Why are metals good conductors of electricity and heat?
The delocalised electrons are free to move and flow
Why do metals have very high melting and boiling points?
They have a strong attraction between the positive ions and delocalised electrons
Why are metals malleable and ductile?
There are layers of ions that can slide over each other
What are the factors that affect ionisation energy?
Atomic Radius
Nuclear Charge
Electron Shielding
Explain the trend in ionisation energy across Period 3
•Ionisation Energy increases because of increased nuclear charge, decreased atomic radius and same electron shielding which means more energy is required to remove the first electron
•Dips at Aluminium as the outer electron is in a p orbital, which is a higher energy level than s orbital, meaning less energy is needed to remove electron
•Dips at Sulfur as one of the p orbitals contains two electrons in a pair meaning more repulsion, so less energy is needed to remove one
Why does first ionisation energy decrease between Group 2 to 3?
In Group 3 the outermost electrons are in p orbitals whereas in Group 2 they are in s orbitals, so the electrons are easier to be removed
Why does first ionisation energy decrease between Group 5 to 6?
The Group 5 electrons in p orbitals are single electrons and in Group 6 the outermost electrons are spin-paired, with some repulsion. Therefore the electrons are slightly easier to remove.
Does first ionisation energy increase or decrease between the end of one period and the start of the next? Why?
Decrease
There is an increase in atomic radius
Increase in electron shielding
What are the properties of giant metallic lattices?
High melting and boiling point
Good electrical conductors
Malleable
Ductile
