Chapter 2: The Periodic Table Flashcards
What was the first incident of successful medical treatment of a mental illness?
The first incident of successful medical treatment of a mental illness was in the 1940s by John Cade, using lithium to treat mania.
Who first published the periodic table of elements and how does that first publication differ from modern publications?
Dmitri Mendeleev, 1869. His initial publication ordered elements by atomic weight. Modern, and more accurate, periodic table uses increasing atomic number rather than atomic weight for the periodic pattern of elements.
What is the periodic law?
The periodic law states the chemical and physical properties of the elements are dependent, in a periodic way, upon the atomic numbers.
What are the rows and columns called on a periodic table?
The rows are called periods.
They are called groups.
How many periods are on the periodic table of elements, And what are they represented by?
There are seven periods (rows) representing the principal quantum number n=1 through n=7 for the s and p block elements. Each period is filled sequentially, and each element in a given period has one more proton and one more electron than the element to its left (in their natural states).
What is responsible for the similarity amongst elements in the same group?
Groups contain elements and have the same electric configuration in their valence shell and share similar chemical properties.
What are valence electrons (describe them in regard to their potential energy and reactivity)?
Valence electrons are electrons located in the valence shell and are the farthest from the nucleus and have the greatest amount of potential energy. Their potential energy and the fact that they are held less tightly by the nucleus allows them to become involved in chemical bonds with the valence electrons of other atoms. Thus, the valence shell electrons largely determine the chemical reactivity and properties of the element.
Do elements with similar valence electron configuration generally behave in similar ways?
Yes, elements with similar valence electron configurations generally behave the same way as long as they are the same type: metal, nonmetal, or metalloid.
What do the Roman numerals above each group represent on the periodic table?
The Roman numerals above each group represent the number of valence electrons elements in that group in their natural state.
What are the letters associated with the Roman numeral on the groups of the periodic table and what do they represent?
The letters A and B are associated with the Roman numerals in the groups on the periodic table.
A are representative elements and include IA-VIIIA. The elements in these groups have their valence electrons in the orbitals of either s or p. They are called representative elements because their chemical properties closely reflect the typical characteristics of the group they belong to.
B are non-representative elements and include both the transition elements (valence electrons in s and d subshells) and the lanthanide and actinide series (valence electrons in the s and f subshells). They are called non representative because they have unexpected electron configurations.
Together, what do the Roman numeral and letter designation of a group represent?
Provide an example from the book.
Together the Roman numeral and letter designation of a group on the periodic table determine the electron configuration.
For example, an element in group VA has five valence electrons with the configuration s2p3.
The nonrepresentative elements (group B) may have unexpected electron configurations. There are two primary examples of this that I am expected to know. What are those two primary examples?
The two primary examples of nonrepresentative groups on the periodic table are chromium and copper (and general members of their group).
You would expect chromium to be [Ar]4s2 3d4, but it is actually [Ar]4s1 3d5.
You would expect copper to be [Ar]4s2 3d9, but it is actually [Ar]4s1 3d10.
Mendeleev’s table was arranged by atomic weight, but the modern periodic table is arranged by:
Atomic number
Which of the following are representative elements (A), in which are nonrepresentative (B)?
What are the three large categories of chemical reactivity and physical property trends on the periodic table?
The three large categories referred to in the question are metals, nonmetals and metalloids.
Where are the metals found on the periodic table?
The metals are generally found in the left side and middle of the periodic table and include the lanthanide and actinide series.
What are the characteristics of metals?
Metals are:
Lustrous (shiny) solids (except for mercury).
They generally have high melting points and densities
They’re malleable and ductile.
They have low effective nuclear charge, low electronegativity (high electropositivity), large atomic radius, small ionic radius, low ionization energy, and low electron affinity.
All of these characteristics are manifestations of the ability of metals to easily give up electrons.
What is an oxidation state and what group usually have two or more oxidation states?
An oxidation state (or oxidation number) is a hypothetical charge assigned to an atom in a compound, representing the number of electrons it appears to have lost or gained when forming bonds with other atoms, essentially describing the degree of oxidation (loss of electrons) of that atom within a molecule; it is calculated based on the assumption that all bonds are fully ionic, even if the actual bonding is covalent.
Many of the transition metals (Group B elements) have two or more oxidation states.
What causes metals to be good conductors of heat and electricity?
Metals are good conductors of heat and electricity because the valence electrons of all metals are only loosely held to their atoms, they are free to move around.
Also remember metals easily give up electrons.
Where are nonmetals typically found on the periodic table?
Nonmetals are predominantly on the upper right side of the periodic table.
What are the characteristics of nonmetals?
Nonmetals are generally brittle in the solid state and show little or no metallic luster.
They have high ionization energies, electron affinities, and electronegativities, as well as small atomic radii and large ionic radii. They are usually poor conductors of heat and electricity.
All of these characteristics are manifestations of the inability of nonmetals to easily give up electrons. Nonmetals are less unified and their chemical and physical properties than the metals.
Where are the metalloids found on the periodic table?
The metalloids separate metals and nonmetals in a stairstep group of elements on the periodic table.
What’s another name for metalloids and why are they called that?
Another name for metalloids or semimetals. They were called semi metals because they share some characteristics with both metals and nonmetals.
How many metalloids are there, and what are they?
There are eight metalloids on the periodic table and they are:
Boron, silicone, germanium, arsenic, antimony, terrarium, polonium, and astatine.
This does not need to be memorized. But I should be able to recognize the line and which elements are metalloids.
What is LEO GER?
Loss Electron Oxidized (gained positive charge)
Gain Electron Reduced (gained negative charge)
What is the effective nuclear charge (Zeff), and what impacts the effective nuclear charge?
The effective nuclear charge is a measure of the net positive charge experienced by the outermost electrons.
As one moves from the left to the right across a period, electrons and protons are added one at a time. As the positivity of the nucleus increases, the electron surrounding the nucleus experience a stronger electrostatic pull toward the center of the atom. This causes the electron cloud to move closer and bind more tightly to the nucleus. This electrostatic attraction is called the effective nuclear charge (Zeff).
Does the effective nuclear charge (Zeff) change within a given group? Why? Does the increased n impact the characteristics of the elements within the group?
The Zeff decreases slightly as you move down in a given group, however the Zeff does stay relatively constant amongst elements in a group. Although n increases as you move down a group, and therefor adding more protons and thus positive charge, the amount of e- also increases which shields the increased positivity of the nucleus.
As you go down a group, n increases and therefor more electron orbitals. This puts the valence electrons farther away from the nucleus, allowing for a behavior similar to reduced Zeff.
What are noble gases? Where are they located on the periodic table? Why are the noble gases inert? Describe how another element can achieve a similar level of stability.
Noble gases are group VIIIA on the periodic table, the group on the far right. The noble gases are inert because they have a stable octet formation and have effectively zero electron affinity very high ionization energy.
Elements can gain or lose electrons in order to achieve a stable octet formation representative of the noble gases. The halogens are a good example as they have high ionization energy and high electron affinity.
In what direction does the effective nuclear charge increase? In what direction does the effective nuclear charge decrease?
Why is it important to know this?
Effective nuclear charge (Zeff) increases from left to right, and down to up.
Effective nuclear charge decreases from right to left, and up to down.
It is important to know this because this is the guiding principal behind deriving the trends of the periodic table such as atomic radii, ionic radii, ionization energy, electron affinity, and electronegativity.
Despite the fact that Zeff remains relatively constant down a group of the periodic table, what may explain the effects of a reduced Zeff down a group of the periodic table?
Although Zeff only slightly decreases down a group of the periodic table, the valence electrons are held less tightly to the nucleus due to increase separation between valence electrons and the nucleus, causing the effect of a decreased effective nuclear charge (Zeff).
What is atomic radii and how is it determined?
You can think of an atom as a cloud of electrons surrounding a dense score of protons and neutrons. The atomic radius of an element is equal to 1/2 of the distance between the centers of two atoms of an element that are briefly in contact with each other.
The atomic radius cannot be measured by examining a single atom because the electrons are constantly moving around, making it impossible to mark the outer boundary of an electron cloud.
What happens to the atomic radii as we move left to right across the periodic table and why?
Atomic radius decreases from left to right across the periodic table (Zeff increases from left to right across a period).
THIS TREND IS OPPOSITE OF THE OTHER TRENDS (same for ionic radius)
As we move left to right across a period, protons and electrons are added one at a time to atoms. Electrons are being added only to the outermost shell, and the number of inner shell electrons remains constant. The increasing positive charge of the nucleus pulls the outer electrons more closely inward and holds them more tightly.
What happens to the atomic radius as you move down a group? Why?
The atomic radius increases down a group, the largest atom will be at the bottom.
THIS TREND IS OPPOSITE OF ALL THE OHER TRENDS (same trend as ionic radius)
As we move down a group, the increasing principal quantum number implies that the valence electrons will be found farther away from the nucleus because the number of inner shells is increasing, separating the valence shell from the nucleus.
Where will the largest atom be found within a group and a period?
Within each group, the largest atom will be at the bottom (7th period, n=7)
Withinn a period, the largest atom will be on the left (IA, or group 1)
THIS TREND IS OPPOSITE OF ALL THE OTHER TRENDS (but is the same trend as ionic radius)
What element has the largest atomic radius, and what element has the smallest atomic radius?
The element cesium (Z=55) has the largest atomic radius at 260 pico meters.
The element helium (Z=2) has the smallest atomic radius at 25 pico meters.
THIS TREND IS OPPOSITE OF THE OTHER TRENDS (same for ionic radius)
What is ionic radii? What is the tendency in size depending on the charge of the ion?
Ionic radii is the distance between the nucleus of an ion and the outermost shell of the ion.
The atomic size of the cation will be larger than that of the parent atom, the atomic size of the anion will be smaller than that of the parent atom.
What is the general trend for ionic radius on the periodic table?
The general periodic trend for ionic radius is that it increases as you move down a group on the periodic table, and increases as you move across a period from right to left.
Increases as you go down, increases as you go left.
THIS TREND IS OPPOSITE OF THE OTHER TRENDS (same for atomic radius)
What is the trend for electrons left and right of the metalloid line, and what does this have to do with ionic radius?
Elements to the left of the metalloid line (metals) tend to lose electrons and form cations which are much smaller than their parent atom.
Elements to the right of the metalloid line (nonmetals) tend to gain electrons and form and ions, which are much larger than their parent atom.
Relate effective nuclear charge (Zeff) atomic radii and ionic radii.
Since the effect of nuclear charge increases left to right across a period, atomic radius decreases from left to right across a period. Zeff remains constant down a group, but the valence electrons are held less tightly as you move down because of increased quantum number and more filled inner shells, therefore the atomic radius increases down a group.
Since Zeff increases from left to right, ionic radii decreases left to right. Although the effective nuclear charge remains relatively constant down a group (slightly decreases), valence electrons are held less tightly as you move down because of increased quantum number and more inner shells filled, therefore ionic radius increases as you move down a group.
Remember that atomic and ionic radius increase left and down. This trend is opposite of all of the other trends discussed (ionization energy, electron affinity, and electronegativity).
Compare atomic radius and ionic radius.
Atomic radius refers to the size of a neutral element, while ionic radius is dependent on how the element ionizes based on its elements type and group number.
They have the same trend, they both increase as you move left and down. This trend is opposite of ionization energy, electron affinity, and electronegativity.
What is ionization energy (aka ionization potential)?
Ionization energy is an energy required to move an electron from a gaseous species. Removing an electron from an atom always requires an input of heat, which makes it an endothermic process.
As effective nuclear charge increases, what happens to the ionization energy? Why?
As effective nuclear charge increases, ionization energy increases.
This is because the effective nuclear charge holds electrons closer, including the valence electrons, making them more tightly bound.
Which group has the highest ionization energy?
The noble gases are among the elements with the highest ionization energy, meaning they are least likely to give up electrons, because they already have a stable electron configuration in our unwilling to disrupt that stability by giving up an electron.
What is electron affinity?
Electron affinity refers to the energy dissipated by a gaseous species when it gains an electron.
What is the periodic trend for ionization energy?
What is the periodic trend for electron affinity?
Why does electron affinity increase left to right, and down to up on the periodic table?
The stronger the electrostatic pull (higher effective nuclear charge) between the nucleus and the valence electrons, the greater the energy release will be when the atom gains the electron.
Because the valance shell is farther away from the nucleus as the principal quantum number increases, electron affinity decreases in a group from top to bottom.
What groups have low electron affinities, high electron affinities?
Groups 1 and 2 (IA and IIB) have low electron affinity as they prefer to give up electrons to achieve the octet configuration of the noble gas in the previous period.
Group VIIA (17) elements have very high electron affinities because they need to gain only one electron to achieve the octet configuration of the noble gases in the same period.
What is the electron affinity of the noble gases (VIIIA, group 18)?
The electron affinity of the noble gases is effectively zero because they already possess a stable octet and cannot readily accept an electron.
What is electronegativity?
Electronegativity is a measure of the attractive force that an atom will exert on an electron in a chemical bond. The greater the electronegativity of an atom, the more it attracts electrons within an a bond.
What is the periodic trend for electronegativity?
