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
how many p electrons are there in each shell?
6
Where are d orbitals present?
from n=3 upwards
each shell contains five d orbitals
How many d electrons are there in each shell?
10
Where are f orbitals present?
from n=4 upwards
each shell contains 7 f orbitals
how many f electrons are there in each shell?
14
What is the only way that two electrons can fit in the same orbital?
if they have opposite spins
How to electrons occupy orbitals
like bus seats
each electrons will take up an empty orbital in that sub-shell until all orbitals have one electrons in, then they double up
How do electrons occupy sub-shells?
in order of increasing energy levels
What is the electronic configuration of boron?
1s2 2s2 2p1
What is the electronic configuration of oxygen?
1s2 2s2 2p4
Explain the 3d 4s sub-shell overlap
The 4s sub-shell has a lower energy level than the 3d sub-shell
the 4s-orbital fills before the orbitals in the 3d sub-shell
the 4p-orbital starts to fill after the 3d-orbital is full
The larger the value of principal quantum number the ……
higher the energy level and the further the shell is from the nucleus
On the periodic table which elements are included in the s block?
group 1 and 2
On the periodic table which elements are included in the p block?
groups 3 - 8/0
on the periodic table which elements are included in the d block?
the transition metals
For atoms with many electrons how is the electronic configuration abbreviated?
by naming the noble gas which comes before it and then continuing with the electronic configuration from there
how do you alter the electronic configuration for ions?
if it is a negative ion, electrons have been added meaning the electronic configuration would increase 1 place for a 1- ion
if it is a positive ion, electrons are lost meaning the electronic configuration would decrease 1 place for a 1+ ion
What are the exception to the rule ions which you need to be aware of and how do they change?
Sc and Zn, at the top of the d-block
after the 4s orbital has been filled it is actually at a higher energy level so the 4s electrons are lost before the 3d level
What are with 6 noble gases?
helium, He neon, Ne argon, Ar krypton, Kr xenon, Xe radon, Rn
Give two properties of noble gases regarding electrons?
all electrons are paired, with opposite spins
the outer shell contains 2 electrons (for He0 or 9 electrons (for all other noble gases)
