Atomic structure and the periodic table Flashcards
(39 cards)
What is relative atomic mass and formula
The mass of an element compared to 1/12 mass of a C12 atom
Ar =( average mass of atom of element / mass of one atom of c12 )
x 12
What do relative isotopic mass and relative molecular mass use instead
relative isotopic mass uses mass of isotope and relative molecular mass uses mass of molecule
As the distance from the nucleus increases how does this affect energy
Higher energy of shells
What is Heinsberg’s uncertainty principle
You cannot say exactly where an electron is if you know its speed
State Aufbau’s principle
electrons enter the lowest energy level first before filling the rest
what is Hund’s rule of maximum multiplicity ?
When two or more orbitals of equal energy (or very close energy) are available, electrons will fill the orbitals singly before filling doubly.
What is the max number of electrons each shell can hold
2n^2 where n = the number of energy levels
What is an atomic orbital
region around a nucleus which can hold up to two electrons with opposite spins
What is an electron ?
Cloud of negative charge
What are the 4 orbitals
- s orbital, spherical shape. Each shell has a single s orbital
- p orbital. dungbell shape. each shell except for first shell has 3p orbitals
- d orbital. various shapes. each shell except first and second have 5d orbitals
f orbital. 7 different f orbitals found in shell 4 and above
What are the three rules for filling atomic orbitals
- orbitals with lowest energy are filled first
- up to two electrons in each orbital if they have opposite spins
- if you have orbitals with same/ close energy you put electrons in individual orbitals first before doubling up
What is the config for copper
1s^2 2s^2 2p^6 3s^2 3p^6 3d^10 4s^1
What is the electronic config for chromium
1s^2 2s^2 2p^6 3s^2 3p^6 3d^ 5 4s^1
Explain the electronic configuration exceptions for chromium and copper
3d sub shell is more stable when completely full or partially full
for Cr if there is only one electron in 4s subshell as opposed to two can have a half full 3d subshell
for Cu by having 1 electron in 4s subshell, can have a completely full 3d subshell
What do groups 1 and 2 of periodic table correspond to
s1 and s2 subshells
What does the transition block of metals correspond to
d1- d10 subshells
What does group 3- 8 of the periodic table correspond to
p1 - p6 subshells
Why are electrons in 4s always lost before 3d ones ?
4s subshell has a lower energy
What is first ionisation energy ?
energy needed to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous 1 + ions
What is second ionisation energy ?
energy needed to remove one mole of electrons from one mole of gaseous ions to form one mole of gaseous 2 + ions
What are the three factors which affect ionisation energy ?
number of protons, atomic radius and shielding
What does shielding refer to ?
electrons in the outer shell are repelled by electrons in the inner shells, so as number of inner shells increases attraction between nucleus and outer shell electrons decreases.
How does number of protons affect ionisation energy ?
electrons are attracted to protons in the nucleus due to opposite charges attracting, so the greater the proton number, the greater the force of attraction between outer shell electrons and nucleus.
This would increase the ionisation energy
How does first ionisation energy vary as you go down a group ?
- decreases as you go down group because the atomic radius increases due to more shells and also more shielding also due to greater shell number. Yes the number of protons increases but this is outweighed by the shielding and more shells. Of
