quiz 2 chem 100

Calculate the fractional composition values of the three isotopic forms of neon (20Ne,21Ne, and 22Ne) from the following data: 19.9924amu−90.48%; 20.9938amu−0.27%; 21.9913amu−9.25%.

0.9048, 0.0027, and 0.0925, respectively

How many valence electrons does a fluorine atom ( F) have?

7 Start by writing the electron configuration of the neutral atom: F:1s22s22p5 The valence electrons for a main group element are those of the highest n value, in this case those electrons in 2s and 2p. This means F has 7 valence electrons.

The average mass of a nitrogen atom is 14.006amu from the two isotopes with the following data: 14N - 14.00307amu with 0.9963 fractional abundance; 15N- 15.000108amu with 0.00364 fractional abundance. Calculate the percentage abundance of each isotopic form.

99.63% and 0.364%, respectively

Which of the following explains why there is a decrease in ionization energy for the group containing oxygen in the first four periods compared to the group containing nitrogen?

Group 15 elements have half-filled p orbitals. There is a decrease in ionization energy between groups 15 and 16 in the first four periods because group 15 elements have half-filled p orbitals.

Which element weighs, on average, approximately one atomic mass unit?

Hydrogen, typically containing just one proton and one electron, will have an average mass of approximately one atomic mass unit.

Which element has the core electrons 1s22s22p6?

Na Sodium has one valence electron in the 3s orbital, so all the electrons that have n=2 or less can be considered core electrons.

Which will have an abbreviated electron configuration beginning with the radon core?

Pu Plutonium is on the row immediately after radon, so we abbreviate it as radon core, plus the valence electrons for plutonium.

Which of the following is a molecular compound?

SO2 SO2 is a molecular compound because covalent bonds are formed between non-metal elements.

In which of the following element blocks does the atomic radius generally not tend to increase when moving down within a group?

The atomic radius generally increases when going down a group in all of the above element blocks. In every group, the atomic radius will increase as we move down the table, without exception. This is because each lower period features atoms with an additional shell, and that additional shell is farther from the nucleus.

When considering precise mass, which particle has the greatest mass?

The neutron has slightly more mass than the proton, and much more mass than the electron.

The observation that an atom has slightly less mass than the sum of the masses of its subatomic particles is called which of the following?

This observation, although it follows the conservation of energy, defies the conservation of matter, and is called the mass defect. For example, the nucleus of a helium atom is composed of two neutrons and two protons. The sum of the masses of two neutrons and two protons is 4.03298 amu, while the actual mass of a helium nucleus is found to be only 4.00260 amu. The difference (in this case, 0.03038 amu) is the mass defect for helium. The energy corresponding to the mass defect, using the equation E=mc2, is referred to as the nuclear binding energy.

In general, covalent bonding can occur between which of the following?

Two neutral atoms Covalent bonding occurs between two neutral atoms; the electrons are shared between the two atoms so that each can fill its octet.

What is the abbreviated electron configuration of cesium?

[Xe]6s1 The noble gas from the row above is xenon, so we will need xenon core plus the 6s valence electron.

Halogens will tend to form ions with a charge of

1-

What is the precise mass of the proton?

1.00727 amu

One atomic mass unit is equal to:

1.66×10−24 grams One atomic mass unit is approximately equal to the mass of a proton.

When the symbol [Ne] is used as shorthand in the electron configuration of a bigger element, what core electrons does it represent?

1s22s22p6 Neon has the electron configuration 1s22s22p6, so these are the core electrons that are implied when an element is listed as having a neon core.

What are the core electrons of strontium?

1s22s22p63s23p64s23d104p6 Strontium's full electron configuration is 1s22s22p63s23p64s23d104p65s2. To find its core electrons, we must separate the valence electrons (in this case, 5s2) from all of the complete principal energy level shells (the configuration of the closest noble gas). Thus we isolate the electron configuration of krypton, 1s22s22p63s23p64s23d104p6, from the full electron configuration of Sr. These are its core electrons, which are virtually unreactive as they constitute full octets.

Consider the following electron configurations. Element A: 1s22s1 Element B: 1s22s22p63s1 Element C: 1s22s22p63s23p64s1 Which of the following is the correct order for decreasing IE1 (i.e., largest to smallest)?

A>B>C Elements A,B, and C all belong to the same group (1st group indicated by the valence s orbital). Because atomic radius increases with increasing n (A=2,B=3, and C=4) and IE decreases with increasing atomic radius, we know that ionization energy decreases from A to B to C

Which of the following may contribute to the increased radius of an anion compared to parent atom?

Additional electrons lead to more electron-electron repulsion, which will increase the average distances of all the outer orbitals from the nucleus. Additional electrons may need to occupy higher-energy orbitals, which are farther from the nucleus than the lower-energy orbitals. Anions are larger than their parent atoms due to the additional electrons. Since electrons are all negatively charged, they all repel each other and spread the farther. Additionally, the Pauli Exclusion Principle applies to forming anions, and the additional electrons often must occupy subshells with a greater average distance from the nucleus. The charge of the nucleus does not change because anions are not formed by changing the number of protons in the nucleus - only by changing the number of electrons. The *effective* nuclear charge may decrease, but this is a form of electron-electron repulsion.

Which of the following has the smallest atomic radius?

Atomic radius increases when moving from top to bottom and right to left on the periodic table. Neon has the smallest atomic radius of those listed as choices.

Which ion is isoelectronic with xenon?

Ba2+ If barium loses its two 6s electrons it will lose a shell and attain xenon electron configuration.

What is the electron configuration for the core electrons in bromine?

Bromine's full electron configuration is 1s22s22p63s23p64s23d104p5. From this configuration, we separate the valence electrons (4s24p5) from all of those that constitute full principal energy level shells; that is, the configuration of the closest previous noble gas. The closest noble gas that precedes bromine on the periodic table is argon, with an electron configuration of 1s22s22p23s23p6. These are the core electrons of bromine, which are virtually unreactive as they constitute full octets.

Atoms of the same element can have different:

By definition, atoms of a given element have a particular atomic number (which is the same as the number of protons), but they can have different mass numbers if they have differing numbers of neutrons.

Which of the following is the chemical symbol for carbon monoxide? The carbon monoxide compound contains one carbon and one oxygen atom.

Carbon monoxide is a compound, meaning it is made of more than one element. The chemical symbol for carbon monoxide is CO. co and cO are not valid chemical symbols. Co is the chemical symbol for the element cobalt.

Which of the following has the smallest atomic radius?

Cl Atomic radius increases when moving from top to bottom and right to left on the periodic table. Chlorine has the smallest atomic radius.

Which has the smallest mass?

Electrons have much less mass than protons and neutrons, and all of these are much smaller than an atom.

Elements that have similar electron configurations belong to the same:

Elements in the same group have the same number of valence electrons, so they will be housed in orbitals in a similar way. Thus, they will have similar electron configurations.

Which of the following elements has the highest first ionization energy?

F The first ionization energy generally increases when moving across a period in the periodic table from left to right. All of the elements listed above are in the second period. Therefore, fluorine has the highest first ionization energy because it the furthest to the right in the periodic table.

Which of the following is a molecular compound?

HF HF is a compound consisting of two nonmetals, which will form a covalent bond. Molecular compounds are composed of covalently bonded nonmetals.

Based on their positions in the periodic table, which of the following cations has the largest radius?

K+ has a larger radius than Al3+ and Si4+ because it is located below both of those elements in the periodic table. We know that increasing the principal quantum number n increases the radius of the ion. K+ is also larger than Ca2+ because cations with larger charges are smaller than isoelectronic cations with smaller charges.

Neutral atoms that gain electrons become

Neutral atoms that gain electrons become anions (negatively charged ions). Neutral atoms that lose electrons become cations.

Which of the following species has the largest radius?

O2− For any series of isoelectronic particles, the radius decreases as the atomic number (the number of protons) increases. Note that all of these species are isoelectronic with neon, meaning they all have the same number of electrons. Oxygen has the least number of protons of the species listed (smallest atomic number). Therefore, the electrons in O2− will be the least attracted to the nucleus, and so this ion has the largest radius.

Which of the following is a correct method for determining the number of neutrons in an atomic nucleus?

Since the number of neutrons plus the number of protons is equal to the mass number in an atomic nucleus, subtract the atomic number (which is the same as the number of protons) from the mass number to obtain the number of neutrons.

atomic radius

The atomic radius of atoms generally decreases from left to right across a period. There are some small exceptions, such as the oxygen radius being slightly greater than the nitrogen radius.The atomic radius of atoms generally increases from top to bottom within a group.Atomic radius increases when moving from top to bottom and right to left on the periodic table. Neon has the smallest atomic radius of those listed as choices.

Which of the following have the last electron added in an s or p orbital?

The main group elements have the last electron added in an s or p orbital. This category includes all the nonmetallic elements, as well as many metals and the metalloids. The valence electrons for main group elements are those with the highest n level.

identify the most abundant isotope of sulfur from the given data of fractional abundance values of different isotopes: 32S−0.9499, 33S−0.0075, 34S−0.0425, and 36S−0.0001.

The most abundant isotope will be the one with the largest fractional composition, 32S. It has a fractional composition of 0.9499, which is equal to 94.99%.

The term nuclear charge refers to the precise charge of the nucleus, which, in units of fundamental charge, is equal to the number of protons, Z. The term effective nuclear charge is used to mean the apparent charge that determines the radius of the outermost electron(s) in an atom. Which quantity below can be used to approximate the effective nuclear charge by accounting for shielding by the inner electrons?

Z− the number of shielding electrons If Z is the number of protons, then we must subtract from it the number of shielding electrons to find the remaining positive charge that is attracting the valence electrons, which we call the effective nuclear charge.

The reason that atomic numbers are always integer values is because every element has:

a particular number of protons The atomic number refers to the number of protons in an atom, which is always a specific number for a given element.

Which of the following is true?

all of the above Energy is required to remove electrons, ionization processes are endothermic when cations are being formed, and ionization energy is always positive.

Which subatomic particle weighs significantly less than 1 amu?

an electron An electron weighs only a small fraction of an amu. Although the masses of the proton and neutron aren't exactly 1 amu, they are close. A proton has a mass of 1.0073 amu and a neutron has mass of 1.0087 amu.

Whenever an electron is removed during ionization, it will be

an outermost electron Whichever electron resides in the highest energy orbital, which must be the outermost valence electron, is the one that will be removed first.

Neutral nonmetal atoms typically gain electrons, thus becoming _

anions Nonmetals typically gain electrons to form negatively charged ions, also called anions.

The symbol Fe could refer to which of the following? Select the best answer below.

answer=all of the above an iron atom The element known as "iron." a macroscopic sample of iron all of the above

Which is NOT a property of the alkaline earth metals?

answer=they are gases React with oxygen in a 1:1 ratio. They are shiny. Conduct electricity. They are gases. The alkaline earth metals, in group 2 are solid metals.

Valence electrons:

are available to do chemistry and participate in covalent bonding have the highest energy are lost first all of the above These are all characteristics of valence electrons. Core electrons on the other hand do not participate in chemical reactions, have lower energy, and are lost last.

valence electrons

are in the highest energy level. participate in the formation of chemical bonding. Valence electrons are in the highest energy level and generally participate in the formation of chemical bonding. Core electrons are not involved in bonding and are found in the inner shell orbitals.

The average mass of all the atoms of a particular element is called that element's

atomic mass

The mass of an individual atom is most often described in:

atomic mass units

The average mass of an element is calculated by the formula __________.

average mass=∑i(percent abundance×isotopic mass)i

Which element is the one currently used to define the atomic mass unit?

carbon

What are the names of the polyatomic ions ClO−3 and ClO−2, respectively?

chlorate and chlorite The names of ClO−3 and ClO−2 are chlorate and chlorite, respectively. These are names that are important to memorize as you move forward in chemistry.

What ionic compound is the correct name for CoS?

cobalt (II) sulfide CoS is cobalt (II) sulfide.

The electrons occupying the innermost shell orbitals are known as:

core electrons

Which of the following correctly pair the polyatomic ion with its formula? Select all that apply.

cyanide, CN− chlorate, ClO−3 nitrate, NO−3 The only ion that is incorrectly named is sulfate. The formula for sulfate is SO2−4. All of the other answer choices correctly pair the polyatomic ions with their formulas.

Most exceptions to the trend of decreasing radius moving to the right within a period occur in the

d block In the d block, there is some slight deviation in terms of covalent radius moving to the right along a period.

Using the strict IUPAC naming convention for binary molecular compounds, the name for water (H2O) would be _

dihydrogen monoxide Here, we will need to specify with prefixes that there are two hydrogen atoms and one oxygen atom.

The covalent radius generally increases when moving in which directions on the periodic table?

down and left As we move down the table, shells are added and the radius increases. As we move left on the table, the radius will increase. As we move to the right on the periodic table, the radius will decrease because, as protons are added, the electromagnetic attraction increases, which increases the pull on valence electrons toward the nucleus and, therefore, decreases the radius.

An alternative name for iron(II) chloride is:

ferrous chloride The word ferrous implies the Fe2+ ion.

Which of the following is the correct name for F−?

fluoride The ion name for F− is fluoride. Simple anions are named by replacing the end of the element name with -ide.

An atomic nucleus:

has a mass that is less than the sum of the masses of its protons and neutrons The mass of an atomic nucleus will always be less than the sum of the masses of the protons and neutrons contained within it, by a quantity known as the mass defect.

Which of the following gives all of the information necessary to determine the number of subatomic particles?

he atomic symbol includes the elemental symbol, the atomic number and the mass number. The latter two are the number of protons and the sum of the number of protons and neutrons, so it is possible to find the number of neutrons by subtracting atomic number from mass number.

The electron removed when a neutral atom loses an electron will always be an electron from the:

highest energy orbital The highest energy electron is removed, which will be in the highest energy orbital.

Which of the following is named using the unmodified element name and adding the word "ion"?

imple cations (monatomic cations of elements of only one possible charge) Simple cations are named with their elemental name followed by the word "ion." For instance, Na+ is named the sodium ion.

Effective nuclear charge __________ when moving from left to right across a period.

increases Effective nuclear charge increases when moving from left to right across a period.

The covalent radius __________ as the distance of the outermost electrons from the nucleus __________.

increases; increases The covalent radius increases as the distance of the outermost electrons from the nucleus increases.

The noble gases are also called the:

inert gases

IF7 is called

iodine heptafluoride. We don't need a prefix for iodine, but fluoride will need the prefix "hepta," indicating there are seven of them.

MgSO3 is called

magnesium sulfite Because SO2−3 has one fewer oxygen than a sulfate ion, it is called a sulfite ion, hence magnesium sulfite.

When naming binary covalent compounds, the element listed first will be the one that is

more metallic. The atom farther to the left on the periodic table, which will be the one with more metallic character, will be listed first.

When a neutral atom gains an electron, it will have a

negative charge. Gaining a negatively charged particle will give a neutral atom a negative charge.

Which of the following pairings usually forms molecular compounds?

nonmetal, nonmetal Molecular compounds are usually formed when a nonmetal bonds with another nonmetal.

Deviations to the trend in ionization energy occur because of

orbital symmetry For example, oxygen has a slightly lower ionization energy than nitrogen because nitrogen would lose half-full p orbitals while oxygen would gain half-full p orbitals. The enhanced stability of this orbital symmetry is responsible for the deviation from the trend for these two elements.

What is the general name for polyatomic ions that contain one or more oxygen atoms?

oxyanions Oxyanions are particularly common among polyatomic ions. Oxyanions are polyatomic ions that contain one or more oxygen atoms. Two specific oxyanions are peroxide, O2−2, and hydroxide, OH−.

The idea that elements exhibit recurring properties is called:

periodic law

Which two particles have roughly the same mass?

proton and neutron

For elements in the d block, the first electron removed will be a(n):

s electron Even though d electrons were the last to be added for an element in the d block, and the d orbitals are slightly higher in energy than the s orbital immediately preceding, these elements will lose their outermost s electrons first.

The prefix in subatomic tells us that subatomic particles are:

the basic building blocks of atoms

Which of the following results in an increase in effective nuclear charge per electron?

the removal of electrons from the valence shell The removal of electrons from the valence shell leads to an increase in effective nuclear charge per electron because there are fewer electrons to counter the positive charges of the protons.

What is the name of SnO2?

tin (IV) oxide SnO2 is an ionic compound with a tin cation and the oxide anion. Tin can have multiple charges, so the name must indicate the charge with a roman numeral. To find the charge on the tin cation, use the fact that oxide has a charge of −2. There are two oxide anions, so the charge on the tin cation must be +4 in order to give a neutral charge overall. 1(+4)+2(−2)=0. Therefore, the name of the compound is tin (IV) oxide.

Generally, on the periodic table, ionization energy increases _

up and right Atomic radius and ionization energy follow opposite trends. Atomic radius increases down and left, while ionization energy increases up and right. As we move to the right on the periodic table, we add protons, which contracts the radius and holds electrons more tightly so they are harder to remove.