chapter 25-periodic properties Flashcards
what is the periodic law
which states that the chemical properties of the elements are dependent in a systematic way upon their atomic numbers
what does a group represent
elements that have the same electronic configuration in their valence or outermost shell
what are valence electrons
electrons in the valence shell
-these electrons are involved in chemical bonding and determining the chemical reactivity and properties of the element
what are A elements
representative element
what are representative elements
which have either s or p sublevels as their outermost orbitals
-groups IA through VIIA all of which have incompletely filled s or p subshells of the highest principal number
what are B elements
nonrepresentative elements
what are non representative elements
include the transition elements which have partly filled d sublevels and the lanthanide and actinide series which have partly filled f subshells
all elements seek to gain or lose what and why
valence electrons so as to achieve the stable fully-filled formations possessed by the inert or noble gasses of Group VIIIA
what are some periodic trends
- left to right across a period: protons are added one at a time and the electrons of the outermost shell experience an increasing degree or nuclear attraction becoming closer and more tightly bound to the nucleus
- top to bottom down a given column the outermost electrons become less tightly bound to the nucleus
- both these trend show that Zeff is at a max for elements in the top-right of the table and at a min for those in the bottom-left and help explain elemental properties such as atomic radius, ionization potential, electron affinity, and electronegativity
why going top to bottom are the e become less tightly bound to the nucleus
bc the number of filled principal energy levels (which shield the outermost electrons from attraction by the nucleus) increases downward within each group
what is effective nuclear charge (Zeff):
net positive charge from the nucleus as felt by an electron
what is the atomic radius of an element equal
one-half the distance between the centers of 2 atoms of that element that are just barely touching each other
atomic radii trend
decreases across a period from L to R and increases down a given group
what occupies the majority of the volume of an atom
the electron cloud
will changing the size of the nucleus affect the size of the atom yes or no and why
no the size of the electron cloud will change the radius of an atom but changing the size of the nucleus will not directly affect the size of the atom
atomic size trend in a period and the reason
Left to Right
- electrons are added 1 at a tie to the outer energy shells
- e within the same shell do not shield one another from the attractive pull of protons so since the number of protons is also increasing from L to R across a period the Zeff inceases as well
- the greater the + charge experienced by the valence e the greater the Zeff the closer those e are pulled towards the nucleus and the smaller the atomic radius
atomic size trend in a group and the reason
top to bottom
- the number of e and filled e shells increases but the # of valence e within a group remain the same the valence e will be found farther from the nucleus as they are in progressively larger energy shells
- Zeff will become smaller with distance so valence electrons in higher energy shells will feel less pull from the nucleus
- With more e comes increased repulsion from the additional negative charges therefore increasing the atomic radius
what is ionic radius
radius of a cation or anion
are cations smaller or larger than the corresponding neural atoms and why
small than corresponding neutral atoms since fewer e leads to less repulsion amount the remaining e
are anions smaller or larger than the corresponding neural atoms and why
larger than corresponding neutral atoms bc having a greater number of e causes more repulsion resulting in a greater distance between electrons and a larger atomic radius
what is ionization energy
is the energy required to completely remove an electron from a gaseous atom or ion
trends for ionization energy
- The closer and more tightly an e is to the nucleus the more difficult it will be to remove and the higher the ionization energy
- Increases left to right across a period as Zeff increases
- Moving down a group the ionization energy decreases as Zeff decreases
what is First ionization energy
is the energy needed to remove a second valence electron from the univalent ion to form the divalent ion
what is Second ionization energy
the energy needed to remove a second valence electron from the univalent ion to form the divalent ion
what is the trend from group IA ionization elements and why
low ionization energy bc the loss of an electron results in the formation of a stable noble-gas configuration