Lesson 4: Periodic Table
Where will you find metalloids on the periodic table?
On the border of the dividing line between metals and nonmetals.
Oxygen is more electronegative than Carbon. What does this mean?
Oxygen has a greater power to attract electrons to itself.
Periodic table columns are referred to as _________ while periodic table rows are referred to as _________. Fill in the blanks using the following options: - periods - halogens - metalloids - groups
Periodic table columns are referred to as groups while periodic table rows are referred to as periods.
Look at the following image of the periodic table and visualize the dividing line between metals and nonmetals: http://www.sbcs.qmul.ac.uk/iupac/AtWt/table.gif
Think about the line starting at the left of boron and zig zagging down
True or false? Noble gases are more reactive than halogens because noble gases are more mobile and mixable as gases.
False. Halogens are more reactive than noble gases because halogens have an unpaired electron in their outermost orbital.
Which type of substance will be slightly repelled by an external magnetic field? (A) Diamagnetic (B) Antiferromagnetic (C) Paramagnetic (D) Ferromagnetic
(A) Diamagnetic Diamagnetic substances will be slightly repelled by an external magnetic field. Diamagnetic substances have only paired electrons in its outermost orbital. Helium is diamagnetic
Na+ is an example of which type of substance? (A) Diamagnetic (B) Antiferromagnetic (C) Paramagnetic (D) Ferromagnetic
(A) Diamagnetic Na+ is an example of a diamagnetic substance because it has paired electrons in its outermost orbital.
Alkali metals are found where on the periodic table? (A) Group 1A (B) Period 1A (C) Group 2A (D) Period 2A
(A) Group 1A Alkali metals are found in group 1A (also called group 1) on the periodic table.
Which of the following elements in group 1 is not actually an alkali metal? What is its actual classification? (A) Hydrogen (B) Lithium (C) Sodium (D) Cesium
(A) Hydrogen. It is actually a nonmetal.
Carbon bound to Carbon is what type of bond? How did you know this based on electronegativity values? (A) Nonpolar covalent (B) Polar covalent (C) Ionic (D) Hydrogen
(A) Nonpolar covalent Carbon and Carbon have an electronegativity difference of 0, which is less than .5, making their bond a nonpolar covalent bond.
Carbon (electronegativity of 2.5) bound to Hydrogen (electronegativity of 2.1) is what type of bond? How did you know this based on electronegativity values? (A) Nonpolar covalent (B) Polar covalent (C) Ionic (D) Hydrogen
(A) Nonpolar covalent Carbon and Hydrogen have an electronegativity difference of .4, which is less than .5, making their bond a nonpolar covalent bond.
What is a distinct property of alkali metals?
They are extremely reactive and react with water strongly. You wont find them in their pure state in nature
*CRB* Reactions between elements on opposite ends of the periodic table can be extremely exothermic because both elements are gaining stability by moving closer to the octet rule. Which of the following would NOT be an example of this scenario? Periodic table: http://www.sbcs.qmul.ac.uk/iupac/AtWt/table.gif (A) Li and Cl (B) B and N (C) Ca and O (D) Ra and Po
(B) B and N Both Boron and Nitrogen are on the right side of the periodic table (groups 3A and 5A), and a reaction between Boron and Nitrogen will not have the same strength that a Group 1A or 2A element reacting with a group 6A or 7A element would.
*CRB* Which of the following best explains why elements in the same group share similar chemical properties? (A) Elements in the same group have a similar number of nucleons, giving them similar chemical properties. (B) Elements in the same group have the same number of valence electrons, giving them similar chemical properties. (C) Elements in the same group have the same number of electrons, giving them similar chemical properties. (D) Elements in the same group have various multiples of the first element's valence electrons, giving them similar chemical properties.
(B) Elements in the same group have the same number of valence electrons, giving them similar chemical properties. And also chemical reactivity Having the same number of valence electrons allows the different elements to interact with their environments in similar ways.
Carbon (electronegativity of 2.5) bound to Oxygen (electronegativity of 3.5) is what type of bond? How did you know this based on electronegativity values? (A) Nonpolar covalent (B) Polar covalent (C) Ionic (D) Hydrogen
(B) Polar covalent Carbon and Oxygen have an electronegativity difference of 1.0, which is greater than .5, making their bond a polar covalent bond.
*CRB* When Dmitri Mendeleev published the first periodic table, it was said to be a visual representation of the periodic law. Which of the following best describes the periodic law? (A) Elements' physical properties depend on their atomic numbers in a periodic way. (B) Elements' chemical properties depend on their atomic numbers in a periodic way. (C) Elements' chemical and physical properties depend on their atomic numbers in a periodic way. (D) Elements' chemical, physical, and nuclear properties depend on their atomic numbers in a periodic way.
(C) Elements' chemical and physical properties depend on their atomic numbers in a periodic way.
Alkaline earth metals are found where on the periodic table? (A) Group 1A (B) Period 1A (C) Group 2A (D) Period 2A
(C) Group 2A
Sodium (electronegativity of .9) bound to Chlorine (electronegativity of 3.0) is what type of bond? How did you know this based on electronegativity values? (A) Nonpolar covalent (B) Polar covalent (C) Ionic (D) Hydrogen
(C) Ionic Sodium and Chlorine have an electronegativity difference of 2.1, which is greater than 1.7, making their bond an ionic bond.
Metals are solids at room temperature. The only exception is which metal element? (A) Bromine (B) Cobalt (C) Mercury (D) Manganese
(C) Mercury is the only metal that is not a solid at room temperature. Bromine is a liquid at room temperature, but it is a halogen. Cobalt and manganese are solid metals.
*CRB* The octet rule states that an element will gain or lose electrons to achieve a stable octet formation, like the noble gases have. However, the octet rule has many exceptions. Which of the following is NOT one of the exceptions experimentally seen? (A) Noble gases like Xenon can form covalent bonds using more than eight electrons like XeF6. (B) Helium is a noble gas and relatively inert, even though it only has two valence electrons. (C) Nitrogen can form covalent bonds using more than eight electrons, like in the compound NO3 (with a central Nitrogen and double bonds between 2 O and N) (D) Silicon can form covalent bonds using more than eight electrons, like in SiO4 (with a central Silicon and double bonds between 2 O and Si).
(C) Nitrogen can form covalent bonds using more than eight electrons, like in the compound NO3 (with a central Nitrogen and double bonds between 2 O and N) The octet rule does not have exceptions in period 2, where Nitrogen is found. Also, that description of NO3 in the answer is incorrect.
Which type of substance will be pulled into an external magnetic field? (A) Diamagnetic (B) Antiferromagnetic (C) Paramagnetic (D) Ferromagnetic
(C) Paramagnetic Paramagnetic substances will be pulled into an external magnetic field. Paramagnetic substances have one or more unpaired electrons. Two electrons with parallel magnetic fields, the magnetism will just add together. However two electrons with opposite magnetic fields (+1/2 and -1/2) will cnacel each other out and have no attraction ot a magnetic field (diamagnetic) Carbon is paramagnetic
Carbon is an example of which type of substance? (A) Diamagnetic (B) Antiferromagnetic (C) Paramagnetic (D) Ferromagnetic
(C) Paramagnetic Carbon is an example of a paramagnetic substance because its outermost orbital has unpaired eletrons.
*CRB* The acidity of a compound depends on how well an atom can accommodate a negative charge. How does this relate to electronegativity's trends of increasing moving up and to the right? (A) Acidity will have the same trends because electronegativity is how much an element wants a negative charge, and donating the proton gives it a negative charge. (B) Acidity will have the same trends because electronegativity increases as atomic radius decreases, and a smaller radius will allow a more delocalized negative charge, providing more stability. (C) Acidity will not have the same trends because electronegativity is how much an element wants a negative charge, and donating the proton gives it a negative charge. (D) Acidity will not have the same trends because electronegativity increases as atomic radius decreases, and a larger radius will allow a more delocalized negative charge, providing more stability.
(D) Acidity will not have the same trends because electronegativity increases as atomic radius decreases, and a larger radius will allow a more delocalized negative charge, providing more stability. Acidity increases moving to the right and moving down the periodic table.
*CRB* The Zeff of an element increases from left to right on the periodic table, meaning there is a greater nuclear charge compared to electron shielding. Based on this information, which of the following descriptions of atomic radii trends is correct? (A) Atomic radii increase moving up the periodic table and from left to right because that increased nuclear charge will force the nucleons to repel each other more. (B) Atomic radii increase moving up the periodic table and from left to right because the increased nuclear charge pulls the outer electrons closer to the nucleus. (C) Atomic radii decrease moving up the periodic table and from left to right because that increased nuclear charge will force the nucleons to repel each other more. (D) Atomic radii decrease moving up the periodic table and from left to right because because the increased nuclear charge pulls the outer electrons closer to the nucleus.
(D) Atomic radii decrease moving up the periodic table and from left to right because because the increased nuclear charge pulls the outer electrons closer to the nucleus.
Metals are considered to be: I. Malleable II. Ductile III. Conductors (A) I Only (B) I and II Only (C) II and III Only (D) I, II, and III
(D) I, II, and III Metals are considered to be malleable, ductile, and conductors (of heat and electricity). Some are even lustrous (shiny) solids except for mercury
True or false? Alkaline earth metals are more reactive than Alkali metals because Alkaline earth metals have more electrons.
False. Alkali metals are more reactive than Alkaline earth metals because Alkali metals have an unpaired electron.
If Hydrogen and Lithium both have the same Zeff, why does Hydrogen have a higher ionization energy?
Because Lithium's outer electron is farther away from the nucleus.
An anion is bigger or smaller than its original atom? Why?
Bigger because you are adding an electron, potentially increasing electron repulsion, making it bigger.
Which has a greater electron affinity: Nitrogen or Carbon? Why? Periodic table: http://www.sbcs.qmul.ac.uk/iupac/AtWt/table.gif
Carbon. This breaks the normal electron affinity trend because Nitrogen's new electron will be added to a p orbital with another electron (further away from the nucleus increasing repulsion from nucleus + charge), which increases the amount of repulsion that the new electron will experience.
How do you know how many valence electrons an element has?
Easiest way is to look at the group number above that group. But the more logical way to think about it is how many total electrons that element has in its highest orbital (n). SO things like transition metals will often have two valence electrons due to how the electron configuration system works.
*CRB* True or false? Metalloids can also be called semimetals, because they can alternatively act as metals or nonmetals in the same environment.
False. Metalloids (also called semimetals because they share characteristics with both metals and nonmetals) can act as either metals or nonmetals DEPENDING on the environment. The reactivities of the metalloids are dependent on the elements with which they are reacting For example, Boron will act like a nonmetal when surrounded by Sodium (a metal) but like a metal when surrounded by Fluorine (a non metal)
True or false? Due to their metallic properties, metalloids are considered conductors just as metals are.
False. Metalloids are considered semi-conductors. Metalloids tend to have properties of both metals and non metals . It really just depends on the element
*CRB* True or false? The second ionization energy is larger than the first ionization energy because it is the sum of energy needed to remove both electrons from the neutral element.
False. The second ionization energy is the amount of energy it takes to go from X+ to X2+, and is larger than the first ionization energy because more energy is required to take an electron from a cation than to take an electron from a neutral atom.
What is the difference between first and second ionization energy? Which is typically larger and why?
First ionization energy is the energy to pull away the first electron from an atom and it is smaller than the second ionization energy, which is the energy required to pull the second electron away from the nucleus. Second ionization energy is larger due to lower electron shielding and a smaller distance from the nucleus.
*CRB* In previous IUPAC identification systems, the elements were sorted into groups based upon which sub-shells (s,p,d,f, etc.) housed the valence electrons. Which of the following characteristics and subgroups belonged to group A (the representative elements), and which belonged to group B (the non-representative elements)? I. Can have unexpected electron configurations II. Contain the lanthanide and actinide series (valence electrons in s and f orbitals) III. Contain valence electrons in s and p orbitals IV. Includes transition elements (valence electrons in s and d orbitals
Group A (the representative elements): III. Contain valence electrons in s and p orbitals Group B (the non-representative elements): I. Can have unexpected electron configurations (such as the 4s13d5 type configurations II. Contain the lanthanide and actinide series (valence electrons in s and f orbitals) IV. Includes transition elements (valence electrons in s and d orbitals
Halogens belong to which group as compared to Noble Gases?
Halogens belong to group 7A as compared to Noble Gases, which belong to group 8A.
Note electron affinity trend is:
Increases up and to the right
Why does ionization energy increase as you go up a group? Why does ionization energy increase as you go to the right on a period?
Ionization energy increases as you go up a group and to the right on a period because size is decreasing, meaning the electrons are closer to the positively charged nucleus, making it harder to pull electrons away.
Why does IUPAC not consider Zn(s) a transition metal?
It has a complete d-subshell, even in its +2 cation form. Zn- 4s2 3d10 Zn2+- 3d10 The transition metals are compounds that form at least 1 stable ion where the compound has an incomplete d subshell. Zinc is not a transition metal because it forms only Zn2+ ions with all the 3d electrons present. Reason 4s2 goes away for the ion is because when removing electrons, we want to take from the highest energy subshell in the highest energy shell first (n=4 > n=3)
What is effective nuclear charge (Zeff)?
It is the amount of charge that an electron actually experiences from the nucleus. Zeff= nuclear charge- shielding
We stated previously that transition metals have their valence electrons in both the s and d orbitals. So for example, how many valence lectrons does Manganese have?
It really depends on how you define valence electrons. If you define it as the amount of electrons in the highest energy level then its 2. But if you define valence electrons as the amount of electrons as the electrons that participate in chemical reactions then its 7. Look at it this way, Mn has 2 common oxidation states Mn +2 and MnO4 ^-1. FOr Mn to bind to oxygen, it has an oxidation state of +7 thus, 7 electrons were used for Mn to bind to oxygen.
Which has a greater electron affinity: Lithium or Berylium? Why? Periodic table: http://www.sbcs.qmul.ac.uk/iupac/AtWt/table.gif
Lithium. This breaks the normal electron affinity trend because Berylium's new electron will be added to a far away p orbital, which will experience more shielding than Lithium completing its s orbital. Or you can also see that adding electrons to fully filled or half filled subshells will break tredn (see mcat reveiw sheets)
What metals are considered transition metals?
Metals in the d-block (groups 3 through 12). These are atoms that have an incomplete d subshell or can give rise to ions with an incomplete d subshell
What is a distinct property of alkaline earth metals?
They are reactive as well but not as much as the alkali metals and you also dont find these in their pure state in nature. They are mixed with something else
Draw the electron configurations (dot structures) of Chlorine's valence shell, and Sodium's valence shell.
Recall that metals lose electrons to form bonds with non metals Sodium loses 1 electron and Chlorine gains 1 electron. Sodium and chlorine in these cases are stable when you look at the resulting electron configuration. Recall that things bind to be in noble gas configuration (the most stable configuration). Noble gases are unreactive When sodium loses an electron it goes to neon configuration and when chlorine gains an electron it goes to argon configuration
Why does size increase as you go down a group? Why does size increase as you go to the left on a period?
Size increases as you go down a group because you are adding more shells of electrons. Size increases as you go to the left on a period because electron shielding (where inner electrons prevent nucleus from pulling on the outer electrons that it is attracted to by creating repulsive forces with those outer electrons) remains the same as positive nuclear charge decreases. The more positive the nucleus is the more pull it has on the outer electrons. The inner shell shielding power remains the same from the 2 inner electrons thus the more protons in the nucleus, the more it can overcome that shielding power making the atom smaller hence why atomic radii decreases to the right on the periodic table
A cation is bigger or smaller than its original atom? Why?
Smaller because you are taking an electron away, potentially reducing electron repulsion, making it smaller.
*CRB* The chalcogens belong to which group, containing essential elements for biochemical functions like Sulfur and Oxygen?
The chalcogens belong to group 6A, or group 16.
Why does electron affinity increase as you go up a group? Why does electron affinity increase as you go to the right on a period?
The electron affinity increases as you go up a group because the atom is getting smaller, which means the electron is being added closer to the positively charged nucleus. The electron affinity increases as you go to the right on a period because of increased nuclear charge with the same amount of shielding.
*CRB* True or false? Metals are considered to be good conductors because they can exist in multiple oxidation states. This means that valence electrons are only loosely held by an atom and are free to move.
True. Metals are considered to be good conductors of heat and electricity because they can exist in multiple oxidation states. This means that valence electrons are only loosely held by an atom and are free to move. This is also a description of the term "sea of electrons".
Describe valence electrons and their potential energy:
Valence electrons are the farthest from the nucleus and have the largest amount of potential energy. The high potential energy and the fact that they are less tightly held by the nucleus allows them to become involved in chemical bonds with valence electrons of other atoms
Electron affinity is what?
Where energy is given off adding an electron as an electron has high attraction for a nucleus So an tom gives off energy as you add electrons When an atoms nucleus does not have an affinity for an extra electron, it will take energy to add that electron instead of energy being given off. SO the less pull an electron feels from the nucleus is the less electron affinity
What simple equation illustrates the relationship between effective nuclear charge (Zeff) and electron shielding?
Zeff = Z (nuclear charge) - S (electron shielding)
Look at the following period table and describe the trend for increasing ionization energy: http://www.sbcs.qmul.ac.uk/iupac/AtWt/table.gif
energy required to remove an electron from one mole of gaseous atoms to produce one mole of gaseous ions, The further the electrons away from the nucleus, the less pull it feels making it easier to pull from the atom. We take into consideration the electron shielding.
Number of valance electrons an atom has is equal to:
group number
