Periodicity Flashcards
How is atomic number arranged in the periodic table
From left to right atomic number increases.
How are electrons arranged in groups for the periodic table
Elctrons are arranged into vertical columns called groups.
Each element in the a group has the same properties due as it has the same amount of electrons in its outer shell.
Periodic trend across periods 2 and 3
For each period the S and P orbitals are filled in the same way. The S orbital first requiring two electrons then the P orbital requiring 6 electrons.
How are elemennts classified into blocks
There are 4 blocks (s, p, d, f), corresponding to the highest energy sub-shell of each element.
Describe ionisation energy
The measure of how easily an atom losses electrons to form positive ions
Define the first ionisation energy
The amount of energy required to remove one mole of electrons from one mole of gasseous atoms
what three factors affect ionisation energy (nuclear attraction between the nucleus and electrons)
Nuclear charge
Atomic radius
Electron sheilding
Define Nuclear charge
The greater the number of protons in the nucleus the greater the nuclear attration between the nucleus and electrons
Define atomic radius
The larger the distance between the nucleus and electrons the less the nuclear attraction
Define elctron sheilding
Electrons in the inner most shells repel outer shell electrons, reducing the outer shell electrons nuclear attractive force between them and the nucleus.
Define the secon ionisation energy
The energy required to remove one mole of electrons from one mole of gaseous 1+ ions to form one mole of gaseous 2+ ions.
What evidence is there for different energy levels in an atom?
Succesive ionistaion energies show a large difference in (n and n+1) ionisation energies suggests that an electron must of been removed from a different shell.
What does succesize ionisation energy show for atoms
Their group and their identity.
What overall trends are there in first ionisation energies.
There is a general increase in first ionisatin energies across a period.
There is a general decrease in first ionisation energies down a group.
There is a sharp decrease in first ionisation enrgies as a new period starts.
Why does first ionisation energy increase across a period.
Electron sheilding remains the same, however nuclear charge increases causing atomic radius to also decrease. Increasing the nuclear attraction between the nucleus and outer shell electrons, increasing the first ionisation energy.
