MCAT CHEM CH. 4 Flashcards
ATOMIC STRUCTURE AND PERIODIC TABLE (207 cards)
1
Q
What is the smallest unit of any element?
A
Atom
2
Q
All atoms have a central…?
A
Nucleus
3
Q
What does the nucleus contain?
A
Protons and neutrons
4
Q
What are the protons and neutrons in the nucleus known as?
A
Nucleons
5
Q
Proton charge? Electron charge? Neutrons charge?
A
+, -, 0
6
Q
The # of electrons outside the nucleus equals to…?
A
of protons inside the nucleus
7
Q
How are the electrons held?
A
Electrostatic attraction of the + charged nucleus
8
Q
What is the atomic #? Wha’s the symbol for it?
A
of protons in the nucleus of the atom, Z
9
Q
What does the atomic # uniquely determines?
A
What element the atom is.
10
Q
Where is Z demonstrated when noting an element?
A
Before the element, as a bottom left subscript
11
Q
What is the relationship of the masses between the proton and the neutron?
A
A mass slightly more than one atomic mass unit
12
Q
How much does 1 amu weigh?
A
1.66 X 10^-27
13
Q
What is the mass of an electron?
A
About 0.05 percent he mass of either a proton or a neutron
14
Q
All of the mass of an atom is due to its….?
A
Its nucleus
15
Q
How do we calculate the mass number and what symbol is used to represent it?
A
of protons + # of neutrons in the nucleus of an atom, A
16
Q
What is the formula for mass number?
A
A = Z + N
17
Q
What does N represent in the equation A = Z + N?
A
Number of neutrons
18
Q
How would we write Berylium if it had 5 neutrons? Based on subscript and superscript?
A
Superscript 9, Subscript 4, Be
19
Q
What is an isotope?
A
Two atoms of the same element differ in their number of neutrons
20
Q
How much does the nucleus occupy based on the atom’s size?
A
The nucleus occupies only the tiniest fraction of the atom’s volume
21
Q
In other words,, all isotopes of a given element have….
A
The same atomic number but different mass numbers
22
Q
An atom with 7 neutrons and a mass number of 12 is an isotope of what element?
A
Boron
23
Q
What is the atomic weight of an element?
A
Weighted average of the masses of its naturally occurring isotopes
24
Q
What is an example of an atomic weight of an element with various natural occurring isotopes?
A
Boron
25
What is an ion?
When a neutral atom gains or loses an electron and becomes charged
26
What is a negatively charged ion?
Anion
27
What is a positively charged ion?
Cation
28
What are protons and neutrons held tog ether by?
Strong nuclear force
29
Which force is stronger; nuclear force or electrical force between charged particles?
Nuclear force because it overcomes the electrical repulsion between the protons
30
What are unstable nuclei said to be?
Radioactive
31
What happens to radioactive nuclei?
Undergo transformations to make themselves more stable
32
What type of transformation can a radioactive nuclei undergo?
Altering the number and ratio of protons and neutrons or lowering their energy
33
What is the name of the process of lowering their energy?
Radioactive decay
34
What are the types of radioactive decay?
Alpha, beta and gamma decay
35
What is a parent nucleus?
The nucleus that undergoes radioactive decay
36
What is a daughter nucleus?
The resulting more stable nucleus
37
What does a large nucleus do in order to reduce the number or protons and neutrons?
Emits an alpha particle
38
What does the alpha particle consists of?
2 protons and 2 neutrons
39
How is the alpha particle denoted?
4 superscript 2 subscript alpha
40
What is the alpha particle equivalent to?
Equivalent to a helium-4-nucleus
41
How else can the alpha particle can be denoted?
superscript 4 subscript 2 He
42
What is the effect of alpha decay?
Reduces the parent's atomic number by 2 and the mass number by 4
43
If polonium-210 has a superscript of 210 and a subscript of 84, what would it become?
Stable nucleus lead-206, superscript 206, subscript 82
44
What happens to the alpha particle that are emitted in high energy from the parent nucleus?
Energy is quickly lost as the particle travels through after of air
45
Due to the fact that the energy is quickly lost, how far does it travel?
Does not travel far and can be stopped by the outer layers of skin or a piece of paper
46
What are the three types of beta decay that exists?
B+, B- and electron capture
47
Each type of beta decay involves what?
The conversion of a neutron into a proton
48
What is the force used to complete the conversion of a neutron into a proton?
Weak nuclear force
49
Why particles are more dangerous, beta or alpha? Why?
Beta because they are less massive
50
Because beta particles are less massive, what do they have and what greater ability?
Have more energy and a greater penetrating ability
51
What are examples of stuff that can stop a beta particle?
Stopped by aluminum foil or a centimes of plastic or glass
52
What is called when an unstable nucleus covert a neutron into a proton and an electron?
B- particle
53
How is the atomic number of the resulting daughter nucleus based on B- decay?
1 greater than the radioactive nucleus but the mass number remains the same
54
What isotope is an example of radioactive nucleus that undergoes B- decay?
carbon-14
55
If the MCAT mention beta decay, what does it imply? How do you know that?
B- decay; it's the most common type of beta decay
56
What is term for B+ decay?
Positron emission
57
What happens when an unstable nucleus contains too few neutrons?
It converts a proton into a neutron and a positron which is ejected
58
What is B+ decay?
Ejecting a positron; a proton converted into a neutron
59
What is the positron considered within the nucleus?
The electrons antiparticle
60
Why is the positron considered the electron's anti-particle?
It's identical to an electron except its charge is positive
61
What is the resulting daughter of nucleus based on B+ decay?
Daughter nucleus is 1 less than the radioactive parent nucleus but the mass number remains the same
62
What isotope is an example of radioactive nucleus that undergoes B- decay?
Fluorine-18
63
What is electron capture?
Increase number of neutrons by capturing an electron from the closest shell
64
From which shell is the electron capture taken from?
The n=1 shell
65
What is the electron used when taken from the closest shell?
Use it in the conversion of a proton into a neutron
66
What is the resulting daughter of nucleus based on electron capture?
Causes the atomic number to be reduced by 1 while the mass number remains the same
67
What is an example of electron capture?
Chromium-51
68
What happens to the nucleus after it undergoes alpha or any type of beta decay?
In an excited energy state
69
How can an excited nucleus go back to its ground state?
Emitting energy in the form of one or more photons of electromagnetic radiation
70
What are these photons referred as?
Gamma photons
71
Why can gamma rays penetrate anything easily?
They have neither mass nor charge
72
What type of surface will stop the gamma ray?
Few inches of lead or meter of concrete
73
What is the resulting daughter of nucleus based on electron capture?
Changes neither the atomic number nor the mass number of the nucleus
74
What example was used to show gamma decay?
Silicon-31
75
What is different between alpha/beta and gamma?
Alpha/beta change the identity of the nucleus, gamma does not
76
What does alpha decay do the the number of neutrons and protons?
Reduces number of protons ad neutrons
77
What does beta decay do the the number of neutrons and protons?
Decreases the number of neutrons, increases the number of protons
78
What does positron emission (beta plus) do the the number of neutrons and protons?
Increases the number of neutrons, deceases the number of protons
79
What does electron capture do the the number of neutrons and protons?
Increases the number of neutrons, deceases the number of protons
80
What does gamma ray do the the number of neutrons and protons?
Doesn't change mass number or atomic number
81
What is a half-life?
The time it takes for 1 half-life some sample of the substance to decay
82
The shorter the half-life.....the....
The faster the decay
83
How does the amount of radioactive substance change overtime?
Radioactive substance decreases exponentially with time
84
What is half-life denoted by?
t1/2
85
What is the formula for exponential decay?
N = N0e^-kt
86
What is the easiest way to write the exponential decay formula?
N = N0(1/2)^T/t1/2
87
What does N mean in that formula? (N = N0(1/2)^T/t1/2)
The number of radioactive nuclei remaining
88
What does T mean in that formula? (N = N0(1/2)^T/t1/2)
T is the total time the sample has decayed
89
What does k mean in that formula? (N = N0e^-kt)
k is known as the decay constant
90
What is the relationship with k and half-life?
k is inversely proportional to the half-life
91
How would we calculate k if we only had the half-life equation?
k = (In2)/t1/2
92
What is nuclear binding energy?
Energy released when the individual nucleons were bound together by the strong force to form the nucleus
93
What would the nuclear binding energy equal to?
Energy required to break up the intact nucleus into individual nucleons
94
The greater the binding energy....
the more stable the nucleus
95
Why is the sum of the masses of all its nucleons individually greater than the combined nucleus?
Some mass is converted to energy when the nucleons bind together
96
What is the difference between the energy loss mass during the nucleus binding the nucleons?
Mass defect, triangle mass
97
The energy of the mass defect is equivalent to what?
Equivalent to the nuclear binding energy
98
For stable nucleus, the mass defect would always be what?
Would always be positive
99
How is the equation for mass defect?
Total mass of separate nucleons - mass of nucleus
100
How is the nuclear binding energy denoted?
Eg
101
How can the nuclear binding energy be found?
Using the Einstein's equation for mass-energy equivalence
102
What is Einstein's equation for mass-energy equivalence?
Eg = (trianglem)c^2
103
Based on Einstein's equation for mass-energy equivalence, what does c represent?
C represents the speed of light, 3 X 10^8m/s
104
What is the conversion factor between kg and joules?
1 kg = 9 X 10^16 J
105
What is the nuclear domain and masses expressed in?
Atomic mass units
106
What is the energy expressed in usually?
Electronvolts
107
What is the conversion factor of an électronvolt?
1 eV = 1.6 X 10^-19 J
108
How can the Einstein equation for mass-energy be converted into the eV units?
EB = (ineV) = [trianglem(in amu)] X 931.5 MeV
109
What is an atom's emission spectrum?
Energetic fingerprint that consists of a sequence of specific wavelengths and energies
110
The energy of photons that are emitted are related to what?
Their frequencies and their wavelengths
111
What is the equation of photon emission?
Ephoton = hf = hc/wavelength
112
What does h refer to in the equation of photon emission equation?
Planck's constant
113
What is Planck's constant?
6.63 X 10-34
114
What does c refer to in the equation of photon emission equation?
Speed of light
115
What was the model that Bohr proposed?
Electrons orbited the nucleus in circular paths
116
What did Bohr mention about the distance from the electron to the nucleus?
Distance from the nucleus was related to the energy of the electrons
117
Electrons with greater amounts of energy orbited the nucleus at........
greater distance
118
What can electrons in the atom not assume based on energy and what's the correct term?
Cannot assume arbitrary energy but have quantized energy states
119
What does having quantized energy states means for the electrons orbits?
Can only orbit at certain allowed distances from the nucleus
120
How can an electron jump to a higher level?
If an electron absorbs energy that's exactly equal to the difference in energy between its current level and of its higher level
121
How can an electron drop to a lower energy level?
By emitting a photon with an energy exactly equal to the difference between the levels
122
The Bohr predicted what kind of spectra?
Line spectra
123
What is the ground state represented by? And what does it mean?
n=1, lowest possible energy level
124
What is the excited state?
Jumps to a higher energy level
125
What are Bohr atoms?
Atoms or ions containing one electron
126
What is the Bohr atom equation?
En = (-2.178X10^-18) / n^2
127
When there is a smaller energy change level, the wavelength would be.....
Of longer length because they are inversely related
128
What does the Bohr model fail to demonstrate?
The electron-electron interactions that exist in many-electron atoms
129
What do the quantum numbers designate?
Designating shell, sub shell, orbital and spin
130
What is the energy shell of an electron represented by?
n
131
What is an energy sub shell?
One or more orbitals that describe the shape and energy of the orbitals
132
Based on quantum theory, what is an orbital?
Three-dimensional region around the nucleus in which the electron is most likely to be found
133
What are the denoted letters for subshells?
s, p, d or f
134
Each higher energy shell contains what?
One additional subshell
135
If the first energy shell contains he s subshell, what would the second energy shell contain?
Both the s and p subshell
136
What are degenerate orbitals?
Subshell containing one or more orbitals of the same energy
137
How do the number of orientations differ between subshells?
The number of orientations increases by two in each successive sub shell
138
What is an example of different orientations for subshells
The s sub shell contains one orientation and the p subshell contains three orientations
139
Each electron has how many possible spin states?
Two
140
What can the two spin states be considered?
Can be considered the electron's intrinsic magnetism
141
Because an electron has two possible spin states, how many electrons can an orbital have as max?
Two electrons
142
What are the spins of the two electrons in the orbital?
One spin-up, one spin-down
143
What do we say if an orbital is full?
The electrons it holds are "spin-paired'
144
What are the three basic rules of electron configurations?
1. Electrons at lowest energy orbitals valuable
2. Electrons occur available orbitals singly before pairing
3. No more than 2 in any given orbital
145
What is the Aufbau principle?
Electrons occupy the lowest energy orbitals available
146
What is the Hund's rule?
Electrons in the same sub shell occupy available orbitals singly, before pairing up
147
What is the Pauli exclusion principle?
There can be no more than two electrons in any given orbital
148
What is the electron configurations Oxygen?
1s^2 2s^2 2p^4
149
What is a complete octet and which types of elements have them?
8 valence electrons are in filled subshells and the noble gases
150
What are the noble gases trait related to having a full octet?
Chemical stability and lack of reactivity
151
What is. diamagnetic?
An atom that has all of its electrons spin-paired
152
What are the required factors of a diamagnetic?
Contain an even number of electrons; have all of its occupied subshells filled
153
How is the magnetic field for diamagnetic atom and why?
Magnetic fields they create dance and leave no net magnetic field behind since they are spin-paired
154
Since there is no magnetic field, what happens to an atom that is diamagnetic?
Will be repelled by an externally produced magnetic field
155
What is a paramagnetic atom?
Atom's electrons are not all spin-paired
156
When an external magnetic field is produced, what's the reaction of paramagnetic atoms?
Attracted
157
What is a period in a periodic table?
A period is each horizontal row to the periodic table
158
What is a group or family in a periodic table?
Each vertical column
159
What are the anomalies to the electron configurations rule?
Atoms can achieve a lower energy stately having a filled or half-filled d sub shell
160
What example of atoms are anomalies to the EC rule?
Chromium and same family, Copper and same family
161
What does it mean to be isoelectronic? Provide examples?
Atoms that gain electrons put them in the first available orbital; example: Neon and F-
162
When transition metals lose electrons, from which orbital do they lose it first?
They lose it from the s orbital before losing it from the d
163
Where are transition metals located in the periodic table?
Elements in the d block
164
What is the definition of an excited state?
When electron has jumped to a higher energy level
165
When an electron turns into an excited state, does it change the amount of electrons from the atom?
No, they stay the same amount of electron, just jumped to a higher energy level orbit
166
What's the name of group 1 in a periodic table?
Alkali metals
167
What's the name of group II in the periodic table?
Alkaline earth metals
168
What's the name of group vii in the period table?
Halogens
169
What's the name of group viii in the periodic table?
Noble gases
170
What are the d block elements considered?
Transition metals
171
What are the s and p blocks elements considered?
Representative elements
172
What are the f block elements considered?
Rare earth metals
173
What are alkali metals and alkaline earth metals usually used as in redox reactions?
Reducing agents to lose valence electrons in order to get a stable octet
174
What do halogens usually exist as and why?
As a diatomic molecule (Fsubscript2) where one electron of each atom is shared
Why: Only require a single electron to achieve a stable octet
175
How do halogens behave in redox reactions?
Powerful oxidizing agents - gain electrons
176
What's the valence configurations for alkali metals?
ns1
177
What's the valence configuration for alkaline earth metals?
ns2
178
Whats the valence configuration for halogens?
ns2np5
179
What's the valence configuration for noble gases?
ns2np6
180
What are the elements that possess both metals and nonmetals qualities called?
Metalloids
181
Where are metalloids found in the periodic table?
Diagonal from B to Po
182
What is the shielding effect or nuclear shielding?
Each filled shell between the nucleus and valence electrons shields valence electrons from the full effect of the protons in the nucleus
183
What is Zeff?
The reduced electrical pull from the protons due to the negative charges of the electrons in the filled shells in between
184
When the amount of protons increase.....
Their total pull on the outermost electrons increases too
185
As you move from left to right in the periodic table, what happens to the elements?
The atomic radius decreases
186
Why does the atomic radius decreased from left to right?
Electrons are being added but no new shell so valence electrons feel a stronger pull
187
Why does atomic radius increased from top to bottom when going down a group?
Increase shielding causing less tightly bound since they geed a smaller effective nuclear charge
188
As you move from top to bottom in the periodic table, what happens to the elements?
The atomic radius increases
189
What happens to a cation atomic radius?
Decrease because as e-'s are removed, the ones left are closely pulled in
190
What happens to an anion atomic radius?
Increases
191
What is the atom's first ionization energy (IE)?
The amount of energy necessary to remove the lest tightly bound electron from an isolated atom
192
What happens to the ionization energy when you move from left to right across a period?
Increases because the valence electrons are more tightly bound
193
What happens to the ionization energy when you move from bottom to up across a period?
Increases because the valence electrons are more tightly bound
194
What is the second ionization energy of an atom? (IE2)
The energy required to remove the least tightly bound electron from the cation X+
195
What is electron affinity?
The addition of an electron to an isolated atom
196
What is electron affinity negative?
IF energy is released when the electron is added
197
When is electron affinity positive?
If energy is required to add the electron
198
What type of electron affinity does halogens have and why?
Large negative; the addition of an electron would give them their octet
199
What type of electron affinity does noble gases have and why?
Positives because the added electron begins to fit a new level and destabilizes the electron configuration
200
Which types of elements have positive electron affinity?
Nobles gases and alkaline earth metals
201
What is the electron affinity trend on the periodic table?
Decrease left to right, decreased bottom to up
202
What is electronegativity?
A measure of an atom's ability to pull electrons to self when it forms a covalent bond
203
The greater the tendency to attract electrons.....
The greater the atom's electronegativity
204
What is the elements you have to remember their electronegativity?
F > O > N = Cl > Br > I > S > C = H
205
What is the periodic trend of electronegativity?
Increases from left to right, increases from bottom to top
206
What is acidity of an atom?
How well a compound donates protons, accepts electrons or lowers pH in a chemical system
207
What is the periodic table trend of acidic elements?
Increases from left to right, decreases bottom to up
