MODULE 3: Periodicity Flashcards
How is the periodic table arranged?
Increasing atomic number, periods showing repeating trends (physical and chemical), groups with the same number of outer shell electrons
What is periodicity?
The repeating trend in properties of the elements in a period
What are some of the properties looked at in periodicity?
Electron configuration, ionisation energy, structure and melting/boiling points
What is the pattern of electrons filling shells across periods?
Whatever number the period is, the s and p orbitals are occupied. For example, 3s and 3p are filled in period 3
In the periodic table, what are blocks?
Four groups categorised by the highest energy sub-shell; blocks s, p, d and f
What is first ionisation energy?
The energy required to remove one electron from each atom in one mole of gaseous atoms of an element to form one mole of gaseous 1+ ions
What are the factors that affect ionisation energy?
Atomic radius, nuclear charge, shielding
How does atomic radius affect ionisation energy?
Increasing the atomic radius increases the distance between the outer shell electrons and the nucleus, so therefore decreases the electrostatic forces and the energy required to remove electrons from the outer shell
How does nuclear charge affect ionisation energy?
Increased protons in the nucleus increases the electrostatic forces between the nucleus and the outer shell electrons, therefore increasing the energy required to remove electrons from the outer shell
How does shielding affect ionisation energy?
Increases shielding increases the distance between the outer shell electrons and the nucleus, therefore decreasing the electrostatic attraction and so decreasing the energy required to remove electrons
Using successive ionisation energy, how can you tell how many electrons are in the outer shell?
Looking for the biggest jump in successive ionisation energies
What is second ionisation?
The energy required to remove one electron from each atom in one mole of gaseous 1+ ions of an element to form one mole of gaseous 2+ ions
What can you find out from successive ionisation energy?
Period and group and atom is in, therefore identity of the element
How does first ionisation energy change down a group?
General decreases down a group because of the increased atomic radius and shielding (nuclear charge has little effect)
How does first ionisation energy change across a period?
Increases across a period because of the increased nuclear charge and increased nuclear attraction (shielding doesn’t change and atomic radius has little effect)
