Chem test
Which group contains a metalloid
15
An element that is malleable and a good conductor of heat and electricity could have an atomic number of
29
Why do you think the Cl- ion is larger than a neutral Cl atom?
An electron was added so the attractive force is less.
Which pair of symbols represents a metalloid and a noble gas?
As and Ar
For these elements, state the trend in electronegativity in terms of atomic number.
As atomic number increases, electronegativity increases.
Explain, in terms of atomic structure, why cesium has a lower first ionization energy than rubidium
As atomic radius increases, valence electrons are more easily removed or the force of attraction between the nucleus and the valence electrons decreases going down a group.
In which parts of the table do you find atoms with the highest, and the lowest, ionization energies?
Atoms with the highest ionization energies are located in the top right region of the periodic table. Atoms with the lowest ionization energies are at the bottom left.
Electronegativity is a measure of an atom's ability to
Attract the electrons in the bond between the atom and another atom
Rank the following elements from smallest to largest electronegativity based on the trends you have discovered thus far in the periodic table: barium (atomic number 56), bromine (atomic number 35), and iron (atomic number 26)
Based on the trends of the periodic table, Barium has the smallest electronegativity, then iron, then bromine. Barium has less electronegativity than the others because it has more energy levels that hold electrons. I can also tell that iron is less electronegative than bromine because it has less protons.
Which of the following group 15 elements has the greatest metallic character
Bismuth
Which compound contains ionic bonds?
CaO
Examine other groups and periods in the periodic table to see if the same trends exist. What trends do you see in ionization energy down a group and across a period?
Down a group, the ionization energy decreases. Across a period, the ionization energy increases.
Explain the existence of the trend described in part a in terms of atomic structure and Coulombic attraction.
Electronegativity decreases going down a group because the atom is getting larger and the attractive force becomes weaker the further the electrons are from the nucleus.
What is the trend in electronegativity going down a group in Model 1?
Electronegativity decreases going down a group.
Explain the existence of the trend described in part c in terms of atomic structure and Coulombic attraction.
Electronegativity increases going across a period because the protons increase and there is more pull from the protons in the nucleus
What is the trend in electronegativity going across a period in Model 1?
Electronegativity increases going across a period.
Which list of elements is arranged in order of increasing atomic radii?
F, Cl, Br, I
Which element has atoms with the greatest attraction for electrons in a chemical bond
Fluorine
Which group has the greatest metallic character
Group 1
Which group has the lowest metallic character
Group 17
Which group has high ionization energies but very weak electron affinities? Why do you think this is so?
Group 18 - This is because both electron affinity and ionization energy are highly related to atomic size. Large atoms have low ionization energy and low electron affinity.
Which of these formulas contains the most polar bond
H-F
Which substance contains nonpolar covalent bonds?
H2
Which noble gas has the highest first ionization energy?
Helium
Atoms with loosely held electrons are usually classified as metals. They will exhibit high conductivity, ductility, and malleability because of their atomic structure. Would you expect metals to have high ionization energies or low ionization energies?
I would expect metals to have low ionization energies because their valance electrons are farther away from the nucleus.
In general, what is the trend in ionization energy as you go down a group? Support your answer using examples from three groups.
In general, ionization energy decreases as you go down a group. For example, the ionization energy for H is greater than the ionization energy for Li. Also, the IE for Be is greater than the IE for Mg and the IE for B is greater than the IE for Al.
In general, what is the trend in atomic radius as you go across a period (left to right) in Model 1? Support your answer, using examples from two periods.
In general, the atomic radius decreases as you go across a period from left to right. Two examples would be how Li is larger than Be and how Na is larger than Mg.
In general, what is the trend in ionization energy as you go across a period? Support your answer using examples from two periods.
In general, the ionization energy increases as you go across a period. For example, Li is less than Be and Na is less than Mg.
Which general trend is found in period 2 on the periodic table as the elements are considered in order of increasing atomic number
Increasing first ionization energy
Using your knowledge of Coulombic attraction and the structure of the atom, explain the trend in ionization energy that you identified in Question 7.
Ionization energy decreases as you go down a group because the atom gets larger and it does not take as much energy as the electrons move further away from the nucleus.
What is the relationship between metallic character and ionization energy?
Ionization energy decreases as you move from right to left and from top to bottom.
Using your knowledge of Coulombic attraction, explain why ionization—removing an electron from an atom—takes energy
Ionization takes energy because the electron needs more energy in order to overcome the force that is holding it to the atom.
What happens to the radius as you move across a period?
It decreases
What is the trend in EA down a group?
It decreases
Why do you think the Na+ ion is smaller than a neutral Na atom?
It has one less electron. Since Na has one valance electron, a whole shell is removed to make Na+, causing the ion to be smaller than a neutral Na atom.
What happens to the radius as you move down group 1?
It increases
What happens to the number of protons in the nucleus as you move from one element to the next across a period?
It increases by one with each element.
Write a complete sentence to convey your understanding of atomic radius
It is the distance from the nucleus to the outer most electrons
Which takes more energy, removing an electron from an atom where the nucleus has a tight hold on its electrons, or a weak hold on its electrons? Explain.
It takes more energy to remove an electron from an atom where the nucleus has a tight hold on its electrons because it is strongly attracted.
Which ion has the largest radius
K+
Which substance contains a bond with the greatest ionic character
KCl
Compared to the radius of a chlorine atom, the radius of a chlorine ion is
Larger because chlorine gains an electron
What conclusion can you draw about the ability of metals to hold on to and attract electrons, as compared to nonmetals?
Metals cannot hold on to electrons while non-metals can.
Metals tend to have low ionization energies. What properties of elements in the metal groups do you think are the result of this tendency?
Metals tend to lose electrons easily.
An atom of which element has the largest atomic radius
Mg
Which substance is correctly paired with its type of bonding?
NH3 — polar covalent
As you move across a period, are new energy levels added?
No
What is the trend in EA across a period?
No real trend but it somewhat increases.
Except for the noble gases, nonmetals tend to have high electron affinities. What properties of nonmetals do you think are the result of this tendency?
Non-metals tend to gain electrons easily
As you move down a group, you will recall that the radius increases. Why do you think an increase in atomic radius would result in a lower ionization energy?
Since the radius is larger, the electron is closer and does not have to travel as far to the positive nuclear charge, resulting in a lower ionization energy.
Which occurs when an atom loses an electron
The atom's radius decreases and the atom becomes a positive ion
As the elements in Group 17 on the Periodic Table are considered from top to bottom, what happens to the atomic radius and the metallic character of each successive element?
The atomic radius and the metallic character both increase
In general, what is the trend in atomic radius as you go down a group in Model 1? Support your answer, using examples from three groups.
The atomic radius becomes larger as you go down a group in Model 1. Three examples would be how Li is smaller than Na, Be is smaller than Mg, and B is smaller than Al
Using your knowledge of Coulombic attraction and the structure of the atom, explain the trend in atomic radius that you identifi ed in Question 2. Hint: You should discuss either a change in distance between the nucleus and outer shell of electrons or a change in the number of protons in the nucleus.
The atomic radius becomes larger as you move down groups because new shells are added increasing the distance between the nucleus and the valence electrons.
What are the units for the atomic radius?
The atomic radius is measured in picometers (pm)
Using your knowledge of Coulombic attraction and the structure of the atom, explain the trend in atomic radius that you identifi ed in Question 4.
The atomic radius of elements decrease as you go across a period from left to right because the number of protons increases which in turn increases the attractive force and moves the electrons closer to the nucleus of an atom.
If the proton number increases while the number of energy levels remains constant, what happens to the attractive force between the nucleus and the electrons?
The attractive force will increase.
Explain, in terms of electronegativity, why the H-F bond is expected to be more polar than the H-I bond.
The difference in electronegativity for an H-F bond is 1.8 and the difference for an H-I bond is 0.5. The difference for H-F is greater and therefore more polar. H-F is also more polar because F is more electronegative that I.
What is the relationship between electron affinity and atomic radius? Why do you think this relationship occurs?
The electron affinity increases when the atomic radius decreases.
How do you think the size of an atom will affect its ability to attract additional electrons?
The greater the size of an atom, the lesser the electron affirnity.
In which parts of the table do you find the greatest and lowest attraction for electrons?
The greatest electron affinity is found in column 17. The lowest electron affinity is found in column 18.
Using your knowledge of Coulombic attraction and the structure of the atom, explain the trend in ionization energy that you identified in Question 9.
The ionization energy increases as you go across a period because it takes more energy to remove an electron since the atom is smaller with a stronger nuclear force.
As atomic radius increases, the valence electrons get farther from the nucleus. How do you think an atom's size will affect its ability to hold on to its valence electrons? Why?
The larger the atom is and it's atomic radius is, the less the ionization energy will be.
In which parts of the table do you find the largest and smallest atoms?
The largest atoms are in the bottom left and the smallest atoms are in the top right.
Explain, in terms of electronegativity, why the bonding in NaCl is ionic.
The metal loses an electron to the nonmetal. The sodium atom transfers its one valence electron to the chlorine atom.
In general, what is the effect of the number of energy levels on the radius of an atom?
The more energy levels, the greater the diameter of the atomic radius.
How does you answer to the pervious question explain the trend in radii across a period?
The radius decreases across a period because the attractive force increases.
As you move across a period, you will recall that the radius decreases. Why do you think a decrease in atomic radius would result in a greater ionization energy?
The smaller radius puts the electrons farther away from the positive nuclear charge, causing it to need a greater ionization energy.
Which element is malleable and can conduct electricity in the solid phase?
Tin
Which is a property of most nonmetallic solids
brittleness
As the elements of Group 1 on the Periodic Table are considered in order of increasing atomic radius, the ionization energy of each successive element generally
decreases
When an atom becomes a positive ion, the radius of the atom
decreases
The metallic character of an element is determined by how readily it loses electrons. Elements that lose electrons most easily have the
greatest metallic character.
What are two properties of most nonmetals
high ionization energy and poor electrical conductivity
The ability of carbon to attract electrons is
less than that of nitrogen and oxygen
Which two characteristics are associated with metals
low first ionization energy and low electronegativity
Based on electronegativity values, which type of elements tends to have the greatest attraction for electrons in a bond?
nonmetals
A picometer is
one trillionth of a meter.
Electron affinity (EA)
refers to the energy released when an electron is added to an atom. This release of energy is always expressed as a negative value. The greater the magnitude of the negative value, the greater the attraction for electrons. (An EA of -100 kJ/mol would indicate a stronger attraction for electrons than an EA of -50 kJ/mol.)
The atomic radius is a measure of the size of the electron cloud, or the
region where electrons can be found
Ionization energy (IE) is
the energy required to remove an electron from an atom.
