Ch 5 Sectjon 3 Flashcards
Size of an atom can’t be defined by edge of orbital because this boundary is
Fuzzy and caries under different conditions
To estimate he rice of an atom the conditions under with the atom exists must be
Specified
One way to express an atoms radius is to measure the distance between the
Nuclei of two identical atoms that are chemically bonded together, then divide this distance by two
Atomic radius may be defined as one half the durance between the
Nuclei of identical atoms that are bonded together
There is a gradual decrease in atomic radii from
Across the second period to neon
The trend to smaller atoms across a period is caused by the
Increasing positive charge of the nucleus
As electrons add to s and p sublevels in the same main energy level they are gradually
Pulled closer to the more highly charged nucleus
increased pull results in a
Decrease in atomic radii
the attraction of the nucleus is somewhat offset by
repulsion among the increased number of electrons in the same outer energy level
the difference in radii between neighboring atoms in each period grows
Smaller
The radio of the elements
Increase as you read down the group
As electrons occupy sublevels in successively higher main energy levels located farther from the nucleus the sixes of the atoms
Increase
In general the atomic radii of the main group elements
Increase down a group
The expected increase in fallouts readies caused by the filling of the fourth main remedy level is outweighed by a
Shrinking of the electron cloud caused by s nuclear charge that is considerably higher than that of aluminum
An electron can be removed from an atom if enough
Energy is supplied
A + energy–>
A^+ + e^-
The A^+ represents an ion of element a with a
Single positive charged referred to as a 1+ ion
An ion is an atom or group of bonded atoms that has a
Positive or negative charge
Ionization: any oroceds that
Results in the formation of an ion
To compare the ease with which atoms to different elements give up electrons chemists compare
Ionization energies
Ionization energy (first ionization energy)
The energy required to remove one electron from a neutral atom
To avoid the influence of nearby atoms measurements of ionization energies are made on
Isolated atoms in the gas phase
Group 1 metals have the lowest
First ionization energies in their respective periods
Group 1 metals lose electrons
Most easily
Ease of electron loss is the major reason for
Hugh reactivity of the alkali metals
Group 18 elements have the highest
Ionization energies
Group 18 elements do not
Lose electrons easily
The low reactivity of the noble gases is partly based on thisb
Difficulty of electron removal
In general, ionization energies of main group elements
Increase across each period
Increase in ionization energies across periods is caused by
Increasing nuclear charge
A higher charge more strongly attracts
Electrons in the same energy level
Increasing nuclear charge is responsible for
Both increasing ionization energy and decreasing radii across the periods
In general nobmetals have higher ionization energies than
Metals do
In each period the element of group 1 has the lowest
Ionization energy and the element of group 18 has the highest ionization energy
Among the main group elements ionization energies generally
Decrease down the groups
Electrons removed from atoms of each succeeding element in s group are in
Higher energies and are therefore removed more easily
As atomic number increase going down a group more electrons lie between the
Nucleus and the electrons in the highest occupied energy levels
(More electrons lie between the…) this partially shields the
Outer electrons from the effect of the nuclear charge
These influences overcome the attest toon of the electrons to
Increasing nuclear charge
With sufficient energy electrons can be removed from
Positive ions as well as from neutral atoms
The energies for removal of additional electrons from an atom are referred to as the
Second ionization energy, third ionization energy and so on
The second ionization energy is always
Higher than the first
The third ionization energy is always
Higher than the second
The reason second ie is higher than first, etc is because as electrons are removed in successive ionizations fewer
Electrons remain within the atom to shield the attractive fierce of the nucleus
Each successive electron removed from an ion feels an increasingly
Stronger effective nuclear charge (the nuclear charge minus the electron shielding)
Removing a single electron from an atom in group 18 elements is more difficult than removing an electron from atoms of
Other elements in the same period
The special stability of the noble gas configuration also applies to ions that have
Noble gas configurations
The jump in ionization energy occurs when an ion assumes a
Noble gas configuration
Electrons affinity is the beefy change that occurs when
An electron is acquired by a neutral atom
Most atoms… Energy when they acquire an electron
Release
Release of energy when atoms acquire an electron) A + e^- —>
A^- + energy
Some atoms must be… To gain an..:
Forced to gain an electron by the addition of energy
(Forced gain of electron) A + e^_ + energy —>
A^-
The quantity of energy absorbed would be represented by s positive number but ions produced in this way are
Very unstable and hence the electron affinity for them is very difficult to determine