AS - Unit 1 - Electrons, bonding and structure Flashcards
What is the definition of first ionisation energy?
The energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions
What is electron shielding?
The repulsion between electrons in different inner shells. Shielding reduces the net attractive force from the positive nucleus on the outer-shell electrons
What is the energy needed to form positive ions known as?
Ionisation energy
What is the first ionisation energy for sodium gas?
Na (g) ——–> Na+ (g) + e-
The nuclear attraction experienced by an electron depends on what three factors?
Atomic radium
Nuclear charge
Electron shielding or screening
How does atomic radius affect nuclear attraction?
The greater the atomic radius the smaller the nuclear attraction experienced by the outer electrons
How does nuclear charge affect nuclear attraction?
The greater the nuclear charge the greater the attractive force on the outer electrons
How does electron shielding or screen affect nuclear attraction?
The inner shell electrons repel the outer shell electrons
The repelling is called electron shielding
the more inner shells there are, the larger the shielding effect and the smaller the nuclear attraction experienced by the outer electrons
What are successive ionisation energies?
A measure of the energy required to remove each electron in turn
What is second ionisation energy?
The energy required to remove one electron from each ion in one mol of gaseous 1+ ions to form one mol of gaseous 2+ ions
Why does ionisation energy increase after each level?
Because as each electron is removed there is less repulsion between the electrons and each shell will be drawn in to be slightly closer to the nucleus
as the distance of each electron from the nucleus decreases slightly, the nuclear attraction increases.
Give the definition of a shell
A group of atomic orbitals with the same principal quantum number. Also known as a main energy level
Give the definition for principal quantum number
A number, n, representing the relative overall energy of each orbital, which increases with distance from the nucleus
The sets of orbitals with the same n-value are referred to as electron shells or energy levels
How many electrons are there in the first shell?
2
How many electrons are there in the second shell?
8
How many electrons are there in the third shell?
18
How many electrons are there in the fourth shell?
32
what is an atomic orbital?
A region within an atom that can hold up to two electrons with opposite spins
What are the four different types of orbitals?
s, p, d and f
What shape is an s orbital?
Spherical
Where are the s orbitals present?
from n=1 upwards, each shell contains 1 s orbital.
How many s electrons are there in each shell?
2
What shape is a p orbital?
A three dimensional dumb-bell shape
Where are the p orbitals present?
from n=2 upwards
each shell contains three p orbitals all at right angles to each other