Chapter 8 Flashcards
the pauli exclusion principle
no 2 electrons in an atom can have the same 4 quantum numbers
- an orbital can hold up to 2 electrons and if two electrons are present, they must have opposite spins
- analogy-each seat is uniquely identified and each can hold 1 individual at a time
relationship between energy and orbitals
as the amount of orbitals increase, the energy increases
aufbau principal
the building-up principle is a scheme used to reproduce the ground-state electron configurations y successively filling subshells with electrons in a specific order
-this order generally corresponds to filling the orbitals from lowest to highest energy
hunds rule
- determined how to find the lowest energy configuration of electrons in orbitals of a subshell
- the lowest energy arrangement of e- in a subshell is obtained by putting electrons into separate orbitals of the subshell with the same spin before pairing electrons
- electrons prefer to be in different orbitals because it minimizes electron-electron repulsion
- electrons prefer to have parallel spins because they spend more time apart thus minimizing electron-electron repulsion
what is the most stable arrangement of electrons in subshells
the one with the greatest number of parallel spins
an s shell with 1 orbital can hold a max of _ electrons
2
a p shell with 3 orbitals can hold a max of _ electrons
6
a d shell with 5 orbitals can hold a max of _ electrons
10
an f shell with 7 orbitals can hold a max of _ electrons
14
ground state
the lowest energy configuration of an atom
ex) 1s12s22p63s2
excited-state
any other configuration represents an excited state
valence configuration
the configuration of electrons outside the noble gas or pseudo-noble-gas core
noble gas core example
(NE) 3s2
valence example
3s2
magnetic properties of atoms
an electron behaves like a tiny magnet - 2 electrons of opposite spins cancel each other out - unpaired electrons exhibit magnetic susceptibility
paramagnetic substance
has unpaired electrons
-weekly attracted by a magnetic field
diamagnetic substance
- has only paired electrons
- is not attracted by a magnetic field
why do atoms lose electrons
so that the cation has a noble-gas outer electron configuration
why do atoms gain electrons
so that the anion has a noble-gas outer electron configuration
Mendeleev’s periodic table
generally organized elements by increasing atomic mass and with similar properties in columns. in some places, there were missing elements whose properties he predicted
isoelectronic
having the same numbers of electrons or the same electronic structure
what happens to the electrons when a cation is formed from an atom of a transition metal
electrons are always removed first from the s orbital and then from the (n-1)d orbitals
atomic radius
an atom does not have a definite size . . . but we can define the atom in terms of covalent radii (the radius in covalent compounds)
bond length
the sum of the radii
atomic radii generally increase down a group (column)
the principle quantum number of outer shell increases and the Pauli exclusion principle prohibits the added electrons from occupying the core region
-b/c each successive shell is larger than the previous shell
the principle quantum number decreases from left to right across a period (horizontal row) with increasing atomic number (effective nuclear charge)
effective nuclear charge
the positive charge felt by an electron from the nucleus, increases across a period
shell number n across a period
the same across a period, so each successive atom experiences a stronger nuclear charge => atomic size decreases across a period
the cation is always ____ than the atom from which it is formed
smaller
the anion is always ____ than the atom from which is is formed
larger
first ionization energy
the minimum energy needed to remove the highest energy (outermost) electron from a neutral atom in the gaseous state, thereby forming a positive ion
the bigger the atom (ionization energy)
the easier it is to remove an electron, so the smaller the ionization energy
