Chapter 2 and 3 Flashcards
Nucleon number
Protons + neutrons
Isotopes
Atoms of the same element with different nucleon numbers
Symbol, relative mass and relative charge of subatomic particles
Electron: e, 1/186, -1
Neutron: n, 1, 0
Proton: p, 1, +1
How to find number of neutrons
Nucleon number - number of protons
Symbol for an isotope
A
Element
Z
Isotopes of hydrogen
By number of Neutrons
0: protium
1: deuterium
2: tritium
How many electrons can each principal quantum shells
Shell number: electrons
1: 2
2: 8
3: 18
4: 32
Ionization energy
The first ionization energy of an Elemis the energy needed to remove one electron from each atom in one mole of atoms of the element in the gaseous state to form one mole of gaseous 1+ ions
Successive ionization energies trend
Increases because the charge on the job gets greater as each electron is removed and a greater attractive force between the positively charged nucleus and the negatively charge electrons therefore more energy is needed
3 factors influencing ionization energies
Size of the nuclear charge:
as atomic number increase the positive charge increase, increasing the attractive force between the nucleus and electron so more energy is needed to overcome these attractive forces if an electron is removed
Distance of outer from the nucleus:
the attraction force between the negatively charged electrons and the positively charged nucleus decreases as the electrons in the valence shell distance increases from the nucleus, so less attraction to the nucleus making the force weaker
Shielding effect of inner electrons:
as all electrons are negatively charged they repel each other, electrons in full inner shells repel electrons in outer shells, full inner shells of electrons prevent the full nuclear charge being felt by the outer electrons, the greater shielding the lower the attractive forces between the nucleus and the outer electrons
Deduce sodium successive ionization
First electron has a relatively low 1st ionization energy, it is very easily removed therefore it’s likely to be a long way from the nucleus and shielded by inner electron shells
Second is much more difficult to remove the first, big jump in value of ionization energy, suggests second electron is in a shell closer to the nucleus than the first electron
10th and 11th have extremely high ionization energies, suggest they’re close to the nucleus and there must be a very great force of attraction between the nucleus and electrons and no inner electrons to shield, suggests it’s shell is closer to the nucleus
What ways do we use successive ionization energies
Predict or confirm the simple electronic configuration of elements
Confirm the number of electrons in the outer shell of an element and hence the group to which the element belongs
Name of subshells, how many electrons they can hold, principal quantum levels, their shape, and energy differences
s: 2
p: 6
d: 10
2nd principal quantum level: 2 in s and 6 in p
3rd principal quantum level: 2 in s, 6 in p and 10 in d
S is spherical
P is lobe shaped
s<p></p>
Electronic configuration of potassium
[Ar] 4s1
Outer electron goes into the 4s sub shell rather than the 3d sub shell because the 4s is below 3d in terms of its energy
Filling the 3d subshell
After calcium, a new subshell becomes occupied
Next electron goes into 3d instead of 4p
Scandium [Ar]3d14s2 because electrons occupy the orbitals with the lowest energy the 3d is just above 4s but below 4p
This pattern end siege zinc, [Ar]3d104s2
