Chapter 4
How many electrons are in Bohrs atom
1
A certain radioactive isotope is administered orally as a diagnostic tool to study pancreatic function and intestinal fat absorption. This radiostope is known to undergo B- decay and the daughter nucleus is xenon-131. What is the parent radioisotope?
131^I
Example 4-21 Electron configuration of Aluminum
1s22s22p63s23p1
Example 4-19: Write down—and comment on—the electron con guration of argon (Ar, atomic number 18).
1s: 2 electrons 2s: 2 electrons 2p: 6 electrons 3s: 2 electrons 3p: 6 electrons [Ar] = 1s22s22p63s23p6 Notice that 3s and 3p subshells have their full complement of electrons. In fact, the noble gases (those ele- ments in the last column of the periodic table) all have their outer 8 electrons in lled subshells: 2 in the ns subshell plus 6 in the np. ( e lone exception, of course, is helium; but its one and only subshell, the 1s, is lled—with 2 electrons.) Because their 8 valence electrons are in lled subshells, we say that these atoms—Ne, Ar, Kr, Xe, and Rn—have a complete octet, which accounts for their remarkable chemical stability, and lack of reactivity.
Americium-241 is used to provide intracavitary radiation for the treatment of malignancies. This radioisotope is known to undergo alpha decay. What is the daughter nucleus?
237^Np
An atom contains 16 protons, 17 neutrons and 18 electrons what is the element and how would you write it
33^S^2-
Vitamin B12 can be prepared with radioactive cobalt (58Co), a known β+ emitter, and ad- ministered orally as a diagnostic tool to test for defects in intestinal vitamin B12 absorption. What is the daughter nucleus of 58Co?
58^Fe
Cesium-137 has a half-life of 30 years. How long will it take for only .3 g to remain from a sample of an original 2.4g?
90years
Mass number symbol and definition
A and is the number of neutrons and protons
Explain the process of Gamma decay
A nucleus in an excited energy state—which is usually the case after a nucleus has undergone alpha or any type of beta decay—can "relax" to its ground state by emitting energy in the form of one or more photons of electromagnetic radiation. ese photons are called gamma photons (symbolized by γ) and have a very high frequency and energy. Gamma photons (or gamma rays) have neither mass nor charge, and can therefore penetrate matter most e ectively. A few inches of lead or about a meter of concrete will stop most gamma rays. eir ejection from a radioactive atom changes neither the atomic number nor the mass number of the nucleus. For example, after silicon-31 undergoes β- decay, the resulting daughter nucleus then undergoes gamma decay: 31 Si β - decay 14 31 P∗ γ decay 15 indicates nucleus is in an excited energy state 31 P + 0 γ emitted 15 0 Notice that alpha and beta decay change the identity of the nucleus, but gamma decay does not. Gamma decay is simply an expulsion of energy.
Which of these modes of radioactive decay causes a change in the mass number of parent nucleus
Alpha decay
What are the three types of radioactive decay
Alpha, Beta, and Gamma
What material can stope Beta Decay
Aluminum foil or a centimeter of plastic or glass
Diamagnetic
An atom that has all of its electrons spin paired. diamagnetic atom must contain an even number of electrons and have all of its occupied subshells lled. Since all the electrons in a diamagnetic atom are spin-paired, the indi- vidual magnetic elds that they create cancel, leaving no net magnetic eld. Such an atom will be repelled by an externally produced magnetic eld.
Example 4-18 What's the maximum number of electrons that can go into any s subshell? P subshell? d Subshell?and f subshell
An s subshell has only one possible orbital orientation. Since only two electrons can ll any given orbital, an s subshell can hold no more than 1 × 2 = 2 electrons. A p subshell has three possible orbital orientations (two more than an s subshell). Since again only two electrons can ll any given orbital, a p subshell can hold no more than 3 × 2 = 6 electrons. A d subshell has five possible orbital orientations (two more than a p subshell). Since there are two electrons per orbital, a d subshell can hold no more than 5 × 2 = 10 electrons. Finally, an f subshell has seven possible orbital orientations (two more than a d subshell). Since there are two electrons per orbital, an f subshell can hold no more than 7 × 2 = 14 electrons.
What happens in Electron Capture
An unstable nucleus increases its number of neutrons is to capture an electron from the closest electron shell (the n=1 shell) and use it in the conversion of a proton intro a neutron. Just like the positron emission, electron capture causes the atomic number to be reduced by 1 while the mass number remains the same.
Example 4-23 What is the electron configuration for a silver atom?
As mentioned above, silver is one of the handful of elements with atoms that actually achieve greater overall stability by promoting one of its electrons into a higher subshell in order to make it lled. We'd expect the electron con guration for silver to be [Kr]5s24d9. But, by analogy with copper, we'd pre- dict (correctly) that the actual con guration of silver is [Kr] 5s14d 10, where the atom obtains a more stable state by promoting one of its 5s electrons into the 4d subshell, to give a lled d subshell.
What is a term for a collection of isotopes
Atomic weight of an element
Three rules for electron configuration
Aufbau Principle- electron occupy the lowest energy orbital available Hunds Rule - Electrons in the same subshell occupy available orbitals singly before pairing Pali exclusion Principle- There can only be 2 electrons in an given orbital
Example 4-32: e electrons in a solitary He atom are under the in uence of two forces, one attractive and one repulsive. What are these forces? A) Electrostatic attraction between the electrons and the nuclear protons, and electrostatic repul- sion between the electrons and nuclear neutrons. B) Electrostatic attraction between the electrons and the nuclear protons, and electrostatic repul- sion between the electrons. C) Gravitational attraction between the electrons and the nuclear protons, and frictional repul- sion between the electrons. D) Gravitational attraction between the electrons and the entire nucleus, and frictional repulsion between the electrons
B, because opposites attract. But why is it not C and D
Three types of Beta Decay
B- Decay, B+ Decay (or positron emission), and electron capture
Why does it take energy to remove electrons
Because atoms have a positive nucleus and it is attracted to the negative pull of electrons
What does it mean if an electron is in its spin pair
Because each orbital can only hold 2 electrons up spin or down spin. if an orbital is full, it is in its spin pair.
New shells of an added are on what part of the periodic table?
Beginning of each period
What is more dangerous beta particles or alpha particles
Beta because they are less massive which means they have more energy and greater penetrating ability
Which of the following elements is diamagnetic Sodium Sulfur Potassium Calcium
Calcium
Nucleus
Contains protons and neutrons
Example 4-27: What's the electron con guration of Cu+? Of Cu2+? Of Fe3+?
Copper (Cu, Z = 29) is a transition metal, so it will lose its valence s electrons before losing any d electrons. Recall the anomalous electron con guration of Cu (to give it a lled 3d subshell): [Ar] 4s13d10. erefore, the con guration of Cu+ (the cuprous ion, Cu(I)) is [Ar] 3d10, and that of Cu2+ (the cupric ion, Cu(II)) is [Ar] 3d9. Since the electron con guration of iron (Fe, Z = 26) is [Ar] 4s23d6, the con guration of Fe3+ (the ferric ion, Fe(III)) is [Ar] 3d5, since the transition metal atom Fe rst loses both of its valence s electrons, then once they're ionized, one of its d electrons.
Of the following, which one has the greatest number of neutrons; Ni, Cu^+, Zn, Zn^2+
Cu^+
Nuclear Shielding or the shielding effect
Each lled shell between the nucleus and the valence electrons shields—or "protects"—the valence elec- trons from the full e ect of the positively charged protons in the nucleus. is is called nuclear shielding or the shielding e ect. As far as the valence electrons are concerned, the electrical pull by the protons in the nucleus is reduced by the negative charges of the electrons in the lled shells in between; the result is an e ective reduction in the positive elementary charge, from Z to a smaller amount denoted by Ze (for e ective nuclear charge).
Degenerate orbitals
Each subshell contains one or more orbitals of the same energy and these orbitals have different 3D orientations in space the number of orientations increases by two in each successive subshell. I.e the s subshell contains one orientation and the p subshell contains three orientations
What happens in Beta Decay
Each type of beta decay involves the conversion of a neutron into a proton or vice versa through action of the weak Nuclear force
What does emission spectrum give you the characteristic of
Emission spectrum is an elements energetic fingerprint
Electron Affinity
Energy associated with the addition of an electron to an isolated atom is known as the Electron Affinity
Emission spectrum equation and what. Does it mean
Ephoton = hf Frequency equals speed of light divided by wavelengths ' H- planks constants
Order of electronegativity for the nine most elements
F>O>N» Cl > Br > I > S > C » H
The shorter the half life means what
Faster decay
What does it mean if an electron is in a higher shell
Greater amount of energy and a greater width from the nucleus
Vertical row in a periodic table is the
Group
Binary acid structure
HX
Example 4-15 which is a Bohr atom H He^+ Li^2+ H^+
H^+
Describe Noel Bohrs diagram
He theorized that the electrons orbit the nucleus like the solar system and that the farther the electron was from the nucleus the more energy it had and vice versa. He also thought that electrons were organized in allowed places and had a organized quantinized energy state(s)
Does Alpha Decay have a high or low energy and what can it be stopped by?
High energy and matter travels through air and can be stopped by the outer layer of skin or a piece of paper.
Explain Shielding trends on the periodic table.
However, with progression down a group, as new shells are added with each period, the valence electrons experience increased shielding. The valence electrons are less tightly bound since they feel a smaller e ective nuclear charge. Therefore, as we go down a group, atomic radius increases due to the increased shielding.
What is the denotation for First Ionization Energy
IE_1
What has a greater energy IE or IE_2? And Why
IE_2
Define Acidity
Is a measure of how well a compound donates protons, accepts electrons, or lowers pH in a chemical system.
Second Ionization Energy
Is the energy required to remove the least tightly bound electron from the cation X^+,
What was the error of the Pre-Bohr atom model?
It did not correlate with emission spectrums but instead lacked the lines needed to show the elections moment. It also implied that electrons assumed arbritrary energy levels
Describe the energy shell of an atom
It is denoted as n and is is analogous to circular orbitals
If an electron absorbs energy exactly equal to the difference in energy between its current level and the next level what happens?
It will jump! to a higher level
Define Positron
It's an electrons antiparticle and its identical to an electron except its charge is positive
What is electron spin
It's the two possible spin states, an electrons intrinsic magnetism
What is ionization trend
Left to right on a period Up a group : Ionization energy increases since the valence electrons are or tightly bound
Electronegativity trend
Left to right period electronegativity increases Down a group electronegativity decreases
Define Anion
Negatively charged ion
Who has a bigger ionization energy Neon or lithium ?
Neon is 4 times more greater than that of lithium
Describe the energy subshell
One or more orbitals and is denoted by (s,p,d, or f). Each latter energy becomes more and more complex. Also each energy shell has one or more subshell. And each higher energy contains an additional subshell. An example of this is the first energy shell contains the s subshell and the second energy shell contains both s and p
If all of the spin pairs of an electron is not paired it is
Paramagnetic
How do you find atomic weight of an element with isotopes?
Percent*Isotope + Percent* Isotope=
Horizontal row in a periodic table is the
Period
Define Cation
Positively charged ion
Nucleons
Protons and neutrons
When the number of electrons increase in an atom (across the periodic table), then what else increases
Pull on the outermost electrons
Define Isotopes
Same element differ in their number of neutrons
Define atoms
Smallest unit of any element
Example 4-28: Which of the following could be the electron con guration of an excited oxygen atom? A) 1s22s22p4 B) 1s22s22p5 C) 1s22s22p33s1 D) 1s22s22p43s1
Solution: An oxygen atom contains 8 electrons; when excited, one (or more) of these electrons will jump to a higher energy level. Choice A is the con guration of a ground-state oxygen atom, and choices B and D show the placement of 9 electrons, not 8, so both may be eliminated. e answer must be C; one of the 2p electrons has jumped to the 3s subshell. (Note carefully that an excited atom is not an ion; electrons are not lost or gained; they simply jump to higher energy levels within the atom.
Example: 4-35 Of the following, which has the most negative electron a nity? A) Barium B) Bromine C) Phosphorus D) Chlorine
Solution: Barium is in Group II and therefore has a large positive electron a nity, so we can eliminate choice A immediately. Because electron a nity values tend to become more negative as we go to the right across a row or up within a column, we'd expect chlorine to have a more negative electron a nity than phosphorus or bromine. erefore, choice D is the answer.
Example 4-33 Compared to calcium, beryllium is expressed to have: A) greater electronegativity and ionization energy. B) smaller electronegativity and ionization energy. C) greater electronegativity and smaller ionization energy. D) smaller electronegativity and larger ionization energy
Solution: Beryllium and calcium are in the same group, but beryllium is higher in the column. We therefore expect beryllium to have greater ionization energy and a greater electronegativity than calcium (choice A), since both of these periodic trends tend to increase as we go up within a group.
Example 4-30: Which of the following could describe an ion with the same electron con guration as a noble gas? A) An alkali metal that has gained an electron B) A halogen that has lost an electron C) A transition metal that has gained an electron D) An alkaline earth metal that has lost two electrons
Solution: Choice A is wrong since it says "gained" rather than "lost." Choice B is incorrect since it says "lost" rather than "gained." Choice C is also incorrect, because no element in the d block could acquire a noble-gas con guration by gaining a single electron. e answer must be D. If an element in Group II loses two electrons, it can acquire a noble-gas electron con guration. (For example, Mg2+ has the same con guration as Ne, and Ca2+ has the same con guration as Ar.)
Example 4-29: Which of the following elements has a closed valence shell, but not an octet? A) He B) Ne C) Br D) Rn
Solution: Choice A, He, is the correct choice because He, along with H- and Li+, has a completed n = 1 shell with only 2 electrons, since the n = 1 shell can t only 2 electrons.
Example 4-31: Of the following, the element that possesses properties of both metals and nonmetals is:
Solution: Elements that possess qualities of both metals and nonmetals are called metalloids. ese ele- ments are shown below. us, choice A is the correct answer; the other choices are metals. 5 B 10.8 14 Si 28.1 32 Ge 72.6 33 As 74.9 51 Sb 121.8 52 Te 127.6 84 Po (209) 4.7
Example 4-22: What is the maximum number of electrons that can be present in the n = 3 shell?
Solution: Every new energy level (n) adds a new subshell. at means that in the rst energy level we have only the s subshell, while when n = 2 we have both s and p subshells, and when n = 3, there are s, p, and d subshells. Since there are 1, 3, and 5 s, p, and d orbitals, respectively, for a total of 9 orbitals, and since the maximum number of electrons in an orbital is 2, there can be a maximum of 18 electrons in the n = 3 shell.
Example 4-37: Of the following, which is the strongest acid? A) H2O B) H2S C) HCl D) HBr
Solution: For binary acids, we expect acidity to increase with increasing stability of the conjugate base. When comparing anions in a period, those that are more electronegative are more stable. Since chloride is more electronegative than sul de, choice B can be eliminated. In addition, when comparing anions in a family, those that are larger are more stable, so choices A and C can also be eliminated, making choice D the best answer.
Example 4-34: Which of the following will have a greater value for phosphorus than for magnesium? I. Atomic radius II. Ionization energy III. Electronegativity A) I only B) I and II only C) II and III only D) I, II, and III
Solution: Magnesium and phosphorus are in the same period (row), but phosphorus is farther to the right. We therefore expect phosphorus to have a smaller atomic radius, making Roman numeral I false. is allows us to eliminate choices A, B, and D, leaving C as the correct answer. is is also consistent as we expect phosphorus to have a greater ionization energy and a greater electronegativity than magnesium, since both of these periodic trends tend to increase as we move to the right across a row. However, we expect the atomic radius of phosphorus to be smaller than that of magnesium, since atomic radii tend to decrease as we move to the right across a row. Therefore, the answer is C.
Example 4-26: Which one of the following ions has the same electron con guration as the noble gas argon? A) Na+ B) P2- C) Al3+ D) Cl-
Solution: Na+ (choice A) has the same electron con guration as the noble gas neon, not argon, since one element to the left of Na is Ne. e ion P2- has the same electron con guration as Cl, which is two ele- ments to the right of P. Al3+, like Na+, has the same con guration as Ne. Of the choices given, only Cl- (choice D) has the same con guration as Ar, since Ar is one element to the right of Cl.
Example 4-36: Of the following, which has the smallest atomic radius? A) Sodium B) Oxygen C) Calcium D) Silicon
Solution: The atoms with the smallest atomic radius are those in the upper right portion of the periodic table, since atomic radius tends to increase as we move to the left or down a column. We can therefore eliminate choices A and C; these elements are in Groups I and II, respectively, at the far left end of the ta- ble. To decide between the remaining choices, we notice that oxygen is farther to the right and in a higher row than silicon, so we'd expect an oxygen atom to have a smaller radius than a silicon atom. Choice B is the best answer.
What is the strongest force?
Strong Nuclear Force
The nucleus that undergoes radioactive decay is known as
The Parent
What does the blocks in the table tell us
The block in the table tells us in which subshell the outermost (valence) electrons of the atom will be. e period (row) gives the shell, n, as long as we remember the following fact about the atoms in the d block: electrons for an atom in the d block of Period n go into the subshell (n-1)d. For example, the electron con guration for scandium (Sc, atomic number 21) is [Ar]4s23d1. (Note: if you ever need to write the electron con guration for an element in the f block, the rule is: In the f block, subtract 2 from the period number.)
What are the drawbacks to using glue Bohr model
The drawbacks to using the Bohr model is that it does not account for more than more than one atom. Which means it does not account for electron to electron interaction. Which means that it is good in the aspect of understanding that all atoms have quantinized energy levels
Explain Electron Affinity
The energy associated with the addition of an electron to an isolated atom is known as the atom's electron a nity (often abbreviated EA). If energy is released when the electron is added, the usual convention is to say that the electron a nity is negative; if energy is required in order to add the electron, the electron a nity is positive. e halogens have large negative electron a nity values, since the addition of an elec- tron would give them the much desired octet con guration. So they readily accept an electron to become an anion; the increase in stability causes energy to be released. On the other hand, the noble gases and alkaline earth metals have positive electron a nities, because the added electron begins to ll a new level or sublevel and destabilizes the electron con guration. erefore, anions of these atoms are unstable. Electron a nities typically become more negative as we move to the right across a row or up a group (noble gases excepted), but there are anomalies in this trend.
Atoms that gain electrons accommodate them in what orbital
The first orbital
What amplifies electronegativity
The greater the tendency to attract an electron
Electronegativity
The measure of an atoms ability to pull electrons to itself when it forms a covalent bond.
What happens in Beta- decay
The nucleus contains too many neutrons so it's converted into a proton and a electron (B- particle) is ejected
What happens during Emission spectrum
The photon (particle of light) are emitted
Strong Nuclear Force
The protons and neutrons in a nucleus are held together by a force
What is that quantinized Ion of electrons
The qyantinization of electrons are that there are four levels ( energy levels) to an atom and each levels names are the shell, subshell, orbital and spin
Half Life Definition
The rate of radioactive decay
When an element is put with a symbol like 60 on top and 28 on the bottom for Nickel. What does the 60 represent and what does the 28 represent?
The subscript is N and the superscript is A
What happens if an electron drops energy levels
Then it will emit a photon to do so that is equivalent to the difference of the two energy levels
What is the general rule for electrons jumping energy levels? And why does there have to be this rule.
They can only gain and lose specific amounts of energy (photons ). The reason is there are specific levels of wavelengths.
Example 4-25 What's the electron con guration of P3-? Of Sr+?
To nd the con guration of P3-, we locate phosphorus (P, Z = 15) in the periodic table and move 3 places to the right (because we have an anion with charge of 3-); this lands us on argon (Ar, Z = 18). erefore, the electron con guration of the anion P3- is the same as that of argon: 1s22s22p63s23p6 To nd the con guration of P3-, we locate phosphorus (P, Z = 15) in the periodic table and move 3 places to the right (because we have an anion with charge of 3-); this lands us on argon (Ar, Z = 18). erefore, the electron con guration of the anion P3- is the same as that of argon: 1s22s22p63s23p6
What does the Emission Spectrum consist of
Unique sequence of bright lights that correspond with wavelengths and energy
Define Radioactive
Unstable nuclei
Radioactive decay
Unstable nuclei that needs to be made more stable
Describe the ionization energy of noble gases
Very large
Define Alpha Decay
When a large nucleus wants to become more stable by reducing its number of protons and neutrons. It emits an alpha particle. 2 protons and 2 neutrons
Define Ion
When a neutral atom gains or loses an electron
Explain absorption, emission, and excited States of electrons.
When an electron absorbs, it has a positive energy change. Electron drops to the higher energy level. When this occurs a photon is being absorbed. When emission occurs a electron is releasing a photon and it is a negative electrical change. Thus, during an excited state an electron gets a burst of energy and it will jump up to higher levels from its lowest energy state of its ground state (n=1). it will relax in two ways : either going down one state at a tie which means always emitting a photon with he magnitude of the difference of the two states. Or directly jumping down to a lower state not next to it. This means the photon is at a higher magnitude with is the difference of its current state and the state it wants to go to with is denoted at E_1 - E_3
What happens in B+ Decay
When an unstable nucleus contains too few neutrons, printing is converted into a proton and a positron is ejected.
Why and when does the atomic radius decrease in size?
With progression across any period in the table, the number of protons increases, and hence their total pull on the outermost electrons increases, too. New shells are initiated only at the beginning of a period. So, as we go across a period, electrons are being added, but new shells are not; therefore, the valence elec- trons are more and more tightly bound to the atom because they feel a greater e ective nuclear charge.
What do you do when you get to a d block?
You go and subtract one,
Atomic number definition and symbol
Z and number of protons
An atom with 7 neutrons and a mass number of 12 is an isotope of what element?
Z= A-N 12-7= 5
Electron configuration for Zirconium
[Kr] 5s^24d^2
Note****
e noble gases are often used as starting points, because they are at the end of the rows and represent a shell being completely lled; all that's left is to count over in the next row until the desired atom is reached. We nd the closest noble gas that has an atomic number less than that of the atom for which we want to nd an electron con guration. In the case of chlorine (Z = 17), the closest noble gas with a smaller atomic number is neon (Z = 10). Starting with neon, we have 7 additional electrons to take care of. To get to Z = 17, we go through the 2 atoms in the s block of Period 3 (3s2), then notice that Cl is the fth element in the p block, giving us 3p5. erefore, the electron con guration of chlorine is the same as that of neon plus 3s23p5, which we can write like this: Cl = [Ne] 3s23p.
Isoelectronic
having the same numbers of electrons or the same electronic structure.
What happens after a nucleus undergoes decay
it is in an excited state and
What is the major difference between quantum model and the Bohr model
it is not desire by a circular path because it orbits which means it is a 3 dimensional region around the nucleus. Being "somewhere" not on a perfect circular path
Radioactive calcium-47 a known B- emitter is administered in the form of 47 CaCl2 by I.V.as a diagnostic tool to study calcium metabolism. what is the daughter nucleus of. 47 Ca
scandium-47
Explain Acidity
structure HX, and can dissociate in water in the following manner: HX → H+ + X-. Stronger acids have resulting X- anions that are likely to separate from H+ because they are stable once they do. Generally speaking, the ease with which an acid (HX) donates its H+ is directly related to the stability of the conjugate base (X-). With respect to the horizontal periodic trend for acid- ity, the more electronegative the element bearing the negative charge is, the more stable the anion will be. erefore acidity increases from left to right across a period. However, the vertical trend for acidity depends on the size of the anion. e larger the anion, the more the negative charge can be delocalized and stabilized. erefore, acidity increases down a group or family in the periodic table.
first ionization energy
the energy required to remove the first electron from an atom