Atomic Structure and Periodic Table Flashcards
Why does chromium have a different electronic configuration?
in the case of chromium, the half-filled 3d and 3s sublevels make the atoms of chromium more stable.
What is the electronic configuration of bromine?
[Ar] 3d¹⁰ 4s² 4p⁵
Orbital definition
An orbital is a region within an atom that can hold up to two electrons of opposite spin.
Periodicity definition
A regularly repeating pattern of atomic, physical and chemical properties with increasing atomic number.
First ionisation energy definition
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 the first ionisation of magnesium
Mg (g) –> Mg+(g) + e-
Second ionisation energy definition
The energy required to remove one electron from each 1+ ion in one mole of gaseous ions to form one mole of gaseous 2+ ions
The 1st ionisation energy of potassium
K (g) –> K+ (g) + e-
The overall trend for an ionisation energy across is a period is …… because …….
- increases
- nuclear charge increases
shielding stays roughly the same
atomic radius decreases slightly
The overall trend for an ionisation energy down a group is ….. because……
- decreases
-nuclear charge increases a lot
-shell number increases
-shielding increases
-atomic radius increases - shielding outweighs nuclear charge
Explain why the 1st ionisation energy of sulfur is lower than that of chlorine (2 marks)
- outer electron is removed from same sub shell
- sulfur nuclear charge is 1 less than chlorine
What is Hund’s rule?
- that electrons will occupy the orbitals singly before pairing takes places within every sub shell
What is the Pauli Exclusion Principle?
- that two electrons cannot occupy the same orbital unless they have opposite spins.
- electron spin is shown by the use of upward and downward arrows.
Who discovered the electron?
JJ Thompson
Who discovered the proton?
Ernest Rutherford
Who discovered the neutron?
James Chadwick
What evidence do we have to know that quantum shells exist?
- successive ionisation energies
- emission spectra
where can electron-electron repulsion occur? (sheilding)
- between adjacent quantum shells
- between two electrons in the same orbital
- between electrons in different orbitals within a given quantum shell
How does atomic radii change across period 2/3?
- atomic radii decreases across the group
- because atomic number increases, and therefore the nuclear charge
- this leads to an increase in attractive force (electrostatic) between the nucleus and outer electrons
Definition of relative atomic mass Ar
the average mass of an atom of an element (taking into account the relative abundances of isotopes) compared to one twelfth of the mass of one atom of carbon-12
Definition of relative isotopic mass
the mass of an atom of an isotope compared to one twelfth of the mass of one atom of carbon-12.
What are nucleons
the sub-atomic particles that exist in the nucleus of atoms (protons & neutrons).
What are strong nuclear forces
forces that hold together protons & neutrons in the nucleus.
What are isotopes
atoms of the same element with different numbers of neutrons. (same numbers of protons and electrons)
