periodicity Flashcards
(25 cards)
How are elements arranged in the periodic table? (1)
by increasing atomic (proton) number.
Why do elements in the same group have similar chemical properties? (2)
They have the same number of outer electrons
and the same type of orbitals.
What do elements in the same period have in common? (1)
They have the same number of electron shells.
What is periodicity? (1)
The repeating trends in physical and chemical properties across each period.
What is the periodic trend in electron configuration? (1)
As you go along a period
How are elements in the periodic table divided based on electron configuration? (1)
They are divided into blocks corresponding to their highest energy sub-level.
What is the s-block? (2)
Elements with their highest energy electron in a s sub-shell
Elements in groups 1 and 2
What is the p-block? (2)
Elements with their highest energy electron in a p sub-shell
Elements in groups 13-18
What is the d-block? (2)
Elements with their highest energy electron in a d sub-shell
The transition metals
What is the f-block? (2)
Elements with their highest energy electron in a f sub-shell
The lanthanides and actinides
What is first ionisation energy? (2)
The energy required to remove one mole of electrons
from 1 mole of gaseous ions.
Is ionisation energy an endothermic or exothermic process? (1)
Endothermic because energy is needed to remove an electron.
What is the trend in first ionisation energy across a period? (1)
It increases
Why does first ionisation energy increase across a period? (3)
The number of protons increases, so the nuclear charge increases.
This draws the outer shell closer to the nucleus, decreasing atomic radius.
This increases nuclear attraction, making it harder to remove an electron.
What is the trend in first ionisation energy down a group? (1)
It decreases
Why does first ionisation energy decrease down a group? (3)
The number of electron shells increases.
This increases atomic radius and shielding.
This decreases nuclear attraction, making it easier to remove an electron.
Why does boron have a lower first ionisation energy than beryllium? (5)
The valence electron in beryllium lies in a 2s orbital
The valence electron in boron lies in a 2p orbital
The 2p sub-shell has a higher energy level than the 2s sub-shell.
This makes it easier to remove an electron from the boron 2p orbital
As a result, the first ionisation energy of boron is lower than beryllium.
Why does oxygen have a lower first ionisation energy than nitrogen? (4)
Both oxygen and nitrogen have their highest energy electrons in the 2p sub-shell.
In oxygen, paired electrons in the same orbital repel each other,
Therefore it is easier to remove the valence electron in oxygen
This requires less energy, so the first ionisation energy of oxygen is lower than nitrogen.
What are successive ionisation energies? (1)
Successive ionisation energies occur when more electrons are removed from an atom.
What is the first ionisation energy of aluminium? (1)
Al (g) → Al⁺ (g) + e⁻
What is the second ionisation energy of aluminium? (1)
Al⁺ (g) → Al²⁺ (g) + e⁻
What is the third ionisation energy of aluminium? (1)
Al²⁺ (g) → Al³⁺ (g) + e⁻
What happens to ionisation energy within the same shell? (1)
Successive ionisation energies increase
Why do successive ionisation energies increase? (4)
Electron repulsion between remaining electrons decreases.
Shells of electrons are drawn closer to the nucleus.
Nuclear attraction increases.
More energy is needed to remove each additional electron.
