Chapter 5 Flashcards
In 1860 who presented a method for accurately measuring the relative atomic masses of the elements?
Stanislao Cannizzaro
Who published their first period table in 1869? How did they organize it?
Dimitri Mendeleev
- placed known elements in order using their atomic masses
- recognized that certain properties repeated themselves “peridoically”
- rearranged the elements so that elements with similar properties appeared together in his table
- his procedure left empty spaces from elements that had not been discovered
In 1911 Henry Mosley discovered what?
That the periodic table fit better when the elements were placed in order according to their increasing positive charge
What did Moseley’s work lead to?
The modern definition of atomic number and that atomic number is the basis for organization of the periodic table not atomic mass
What is the periodic law?
The physical and chemical properties of the elements are periodic functions of their atomic numbers
How is the periodic table arranged?
Arranged in order of their atomic numbers so that elements with similar properties fall in the same column or group
A group/family
The vertical columns of the periodic table
Period
The horizontal rows of the periodic table
What are the noble gases?
The group 18 elements which are not reactive (inert)
What are lanthanides
Elements 58-71 at the bottom of the periodic table that are very similar in properties; represent the 4th energy level “f” orbital block elements from period 6
What are actinides?
Elements 90-103 are all radioactive and represent the 5th energy level “f’” orbital block elements from period 7
In each of groups 1-18, the differences between the atomic numbers of successive elements are 8.8.18.18.32
The electron configuration of an atom’s highest occupied energy level governs…
the atom’s atomic properties
How is the length of each period determined?
By the number of electrons that can occupy the sublevels being filled in that period
S-Block Elements
Groups 1 and 2; the s orbital is being filled in the energy level equal to the period number
Alkali metals
Group 1 metals; so reactive that do not exist as pure elements in nature
Alkaline-earth metals
Group 2 metals that also are very reactive and do not exist alone in nature
P-block elements
13-18; the 3 “p” orbitals are being filled in the energy level equal to the period number
Halogens
Group 17 elements
D-Block elements (transition metals)
3-12, in which 5 “d” orbitals are being filled in the energy level equal to the period # minus 1
F block elements
two rows at the bottom of the periodic table that represent 7b “f” orbitals being filled in the energy level that is equal to the period number minus 2
What is atomic radius
One-half the distance between the nuclei of identical atoms that are bonded together
As you go across a period the positive charge of the nucleus _______, the pull exerted on the electron cloud _______ and the atomic radius of the elements decreases across the period.
increases; increases
As you move down a group, each successive element adds an energy level so the atomic radii _________ down a group
increase
What is an ion?
An atoms or group of atoms that has a positive or negative charge
What is ionization?
Any process that results in the formation of an ion
What is ionization energy?
The amount of energy required to remove one electron from a neutral atom of an elements
Ionization energies of the main group elements ________ across a period
increase
Ionization energies of the main group elements usually _________ down a group
decrease
Group 1 metals have the __________ ionization energies. Why?
lowest; they love electrons easily
Group 18 have ___________ ionization energies. Why?
high; don’t lose electrons easily
What is electron affinity?
the energy change that occurs when an electron is acquired by a neutral atom
What is a cation?
An ion with a positive charge due to the loss of electrons
Anion
An ion with negative charge due to the gain of electrons
Halogens ______electrons most readily. What dies this cause?
gain; high reactivity
When atoms become ions their radius…
changes
Formation of a cation leads to a ______ in atomic radius
decrease
Formation of an anion leads to a ________ in atomic radius.
increase
What are valence electrons?
Electrons available to be gained, lost, or shared by atoms in the formation of chemical bonds to make compounds
Where are valence electrons?
In the highest energy levels and often located in incompletely filled orbitals
What is electronegativity
A measure of the ability of an atom in a chemical compound to attract electrons from another atom in the compound
Electronegativity tends to ________ across a period and either _________ or remain ________ down a group.
increase; decrease; the same
What is the most electronegative of the elements?
Fluorine (F)
