General Chemistry Chapters 1-4

Kinetic energy equation

KE = 1/2mv^2 (picture = work energy theorem)

angular momentum equation

L = MVR L = mass x velocity x radius L = moment of inertia x angular velocity L=Iw (curly w = angular velocity) I1W1 = I2W2 can be used to find intertia or angular velocity

Angular momentum of an electron

L=nh/2pi n = principal quantum number h = plancks constant increase in quantum number=increase in angular momentum

paramagnetic

Magnetic resonance angiography (MRA) is a technique that can resolve defects like stenotic (narrowed) arteries. A contrast agent like gadolinium or manganese injected into the blood stream interacts with the strong magnetic elds of the MRI device to produce such images. Based on their orbital con gurations, are these contrast agents paramagnetic or diamagnetic?

atomic mass vs atomic weight

Mass= slightly less than the sum of Protons and Neutrons of the element. Weight= Weighted avg of the isotopes of given element

2n2

Maximum number of electrons within a shell

protons

Positively charged subatomic particles found in the nucleus of an atom

n

Principal quantum number can take on any positive integer value The larger the integer value of ____, the higher the energy level and radius of the electron's shell.

atomic mass unit (amu)

Protons have a mass of approximately one ____ This is also 1/12 the mass of a carbon-12 atom

A photon is emitted

Suppose an electron falls from n = 4 to its ground state, n = 1. Which of the following effects is most likely? A. A photon is absorbed. B. A photon is emitted. C. The electron moves into a p-orbital. D. The electron moves into a d-orbital.

Hund's Rule

Suppose that an atom lls its orbitals as shown: Such an electron configuration most clearly illustrates which of the following laws of atomic physics? A. Hund's rule B. Heisenberg uncertainty principle C. Bohr model D. Rutherford model

the p subshell

The Hund's rule corollary states that half filled and fully filled orbitals have lower energies and thus more stability. What is the one subshell that this is not true for?

Chromium and Copper

The Hund's rule creates two notable exceptions to electron configuration that are often tested on the MCAT:

Bohr

The ____ model's failure was a result of not taking into account the repulsion between multiple electrons surrounding the nucleus. A model resembling planets revolving around the sun in orbits, useful in visualizing the structure of atoms. Bohr postulated that electrons follow a clearly de ned circular pathway or orbit at a fixed distance from the nucleus, whereas modern quantum mechanics has shown that this is not the case

B

The atomic weight of hydrogen is 1.008 amu. What is the percent composition of hydrogen by isotope, assuming that hydrogen's only isotopes are 1H and 2D? A. 92% H, 8% D B. 99.2% H, 0.8% D C. 99.92% H, 0.08% D D. 99.992% H, 0.008% D H + D = 1 (%H + %D = 100%) 1H + 2D = 1.008 (Atomic weight) ------------> H = D - 1 (1-D) + 2D = 1.008 1+D = 1.008 D = 0.008 ------------> H + D = 1 H + .008 = 1 H = 0.992 -----------> multply by 100 to get the percent 99.2 + 0.8 = 100

mole

The atomic weight represents both the mass of the "average" atom of that element, in amu, and the mass of one _____ of the element, in grams For example, the atomic weight of carbon is 12.0 amu, which means that the average carbon atom has a mass of 12.0 amu (carbon-12 is far more abundant than carbon-13 or carbon-14), and 6.02 × 1023 carbon atoms have a combined mass of 12.0 grams. 1 Carbon = 12 AMU 6.022 x 12^23 Carbon atoms = 12 g 12 amu = 12 g = 6.022x10^23 atoms

decreases, increases

The difference in energy between two shells _________ as the distance from the nucleus ________ because the energy difference is a function of ⎢1/n2i − 1/n2f . For example, the energy difference between the n = 3 and the n = 4 shells (1/9 − 1/16) is less than the energy difference between the n = 1 and the n = 2 shells (1/1 − 1/4)

lower, higher

The electrons closer to the nucleus are at ______ energy levels, while those that are further out (in higher shells) have _____ energy. (with respec to electrical potential energy)

Lyman, Balmer, Paschen

The group of hydrogen emission lines corresponding to transitions from energy levels n ≥ 2 to n = 1 is known as the _____ series. The group corresponding to transitions from energy levels n ≥ 3 to n = 2 is known as the _______ series, and includes four wavelengths in the visible region. The Lyman series includes larger energy transitions than the Balmer series; it, therefore, has shorter photon wavelengths in the UV region of the electromagnetic spectrum. The_______ series corresponds to transitions from n ≥ 4 to n = 3.

electrostatic force, greater, gravitational force

The mass of an electron is approximately 1/2000 that of a proton. Because subatomic 2000 particles' masses are so small, the _________ of attraction between the unlike charges of the proton and electron is far _____ than the _______ of attraction based on their respective masses.

smaller, Larger

The only thing the energy equation is saying is that the energy of an electron increases— becomes less negative—the farther out from the nucleus that it is located (increasing n). This is an important point: while the magnitude of the fraction is getting ________, the actual value it represents is getting ________ (becoming less negative). Energy increases in terms of potential. It is farther away, it will cover more distance so it can produce more energy.

azimuthal quantum number

The second quantum number. Designated by the letter l, it means "angular momentum" and refers to the subshell (s, p, d, f, etc.) in which the given electron resides. l can take on the value of an integer in the 0 to n-1 range. -L -angular momentum -shape and number of subshells -range of L=0 to (n-1)

~2.5

The valence electron in a lithium atom jumps from energy level n = 2 to n = 4. What is the energy of this transition in joules? In eV? (Note: RH = 2.18 × 10-18 J = 13.6 eV ) E = (13.6 eV)(1/4 - 1/16)

valence electrons

These electrons have the strongest interactions with the surrounding environment and the weakest interactions with the nucleus (they are involved in bonds and determine the reactivity of an atom)

paired electrons

Two electrons in the same orbital with assigned spins of +1/2 and -1/2.

[Ar] 3d5 (electrons are removed from the 4s orbital first because it has a higher principal quantum number)

What is the electron configuration of Fe3+?

[Ar] 4s2 3d4

What is the electron configuration of chromium?

[Ar] 4s13d10

What is the electron configuration of copper?

[Xe]6s2 4f14 5d6

What is the electron configuration of osmium (Z = 76)?

2n^2

What is the maximum number of electrons allowed in a single atomic energy level in terms of the principal quantum number n? A. 2n B. 2n + 2 C. 2n2 D. 2n2 + 2

Helium

Which of the following atoms only has paired electrons in its ground state? A. Sodium B. Iron C. Cobalt D. Helium

Error in one variable is increased by attempts to measure the other

Which of the following best explains the inability to measure position and momentum exactly and simulta- neously according to the Heisenberg uncertainty principle? A. Imprecision in the de nition of the meter and kilogram B. Limits on accuracy of existing scientific instru- ments C. Error in one variable is increased by attempts to measure the other D. Discrepancies between the masses of nuclei and of their component particles reason: if a particle is moving, it has momentum, but trying to measure that momentum necessarily creates uncertainty in the position.

An electron moves from n = 2 to n = 6

Which of the following electronic transitions would result in the greatest gain in energy for a single hydrogen electron? A. An electron moves from n = 6 to n = 2. B. An electron moves from n = 2 to n = 6. C. An electron moves from n = 3 to n = 4. D. An electron moves from n = 4 to n = 3

4l + 2

Which of the following equations describes the maximum number of electrons that can ll a subshell? A. 2l + 2 B. 4l + 2 C. 2l2 D. 2l2 + 2 subshell = s or p or d or f subshell = l

A

Which of the following is the correct electron con gu- ration for Zn2+? A. 1s22s22p63s23p64s03d10 B. 1s22s22p63s23p64s23d8 C. 1s22s22p63s23p64s23d10 D. 1s22s22p63s23p64s03d8 Reason: The 4s subshell has the highest principal quantum number, so it is emptied rst

6C

Which of the following isotopes of carbon is LEAST likely to be found in nature? A. 6C B. 12C C. 13C D. 14C

B

Which of the following quantum number sets is possible? A. n = 2; l = 2; ml = 1; ms = + 12 B. n = 2; l = 1; ml = -1; m = + 1 ls2 C. n = 2; l = 0; ml = -1; ms = − 1/2 D. n = 2; l = 0; ml = 1; ms = − 1/2 ml = the chemical's magnetic properties

I and II only

Which of the following species is represented by the electron con guration 1s22s22p63s23p64s13d5? I. Cr II. Mn+ III. Fe2+ A. I only B. I and II only C. II and III only D. I, II, and III

electron, proton, neutron

Which subatomic particle is the most important for determining each of the following properties of an atom? 1. Charge: 2. Atomic number: 3. Isotope:

atomic number (Z)

While all atoms of a given element have the same ________, they do not necessarily have the same mass

Yes, this ratio is an equivalent concept. It is acceptable as long as units can be cancelled out.

While molar mass is typically written in grams per mole (g/mol) , is the ratio moles per gram (mol/g) also acceptable?

quantized

a staircase only allows you certain changes in height and, as a result, allows only certain discrete (___________) changes of potential energy.

diamagnetic

a substance in which an all electrons in an atom are paired. The substance is repelled by a magnetic field diamagnetic substances can levitate!

Proton charge (+ 1 e )

e = 1.6 x 10^-19 C

isotope

each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei, and hence differ in relative atomic mass but not in chemical properties; in particular, a radioactive form of an element.

heat, radiation

electrons can be excited to higher energy levels by ______ or _____ to yield excited states

parallel spins

electrons in different orbitals with the same spin (ms)value.

8 p, 10 n, 8 e and 9 p, 9 n, 9 e

in nuclear medicine, isotopes are created and used for various purposes; for instance, 18O is created from 18F. Determine the number of protons, neutrons, and electrons in each of these species. 1.O18: 2.F18:

Electron Orbitals

individual boxes in a subshell (S or P or D or F) that can fit 2 electrons each example orbitals: 2px, 2py, 2pz

magnetic quantum number

ml = -l and +l if l = 2, ml = -2,-1,0,1,2 Specfies the particular orbital within a sub-shell where an electron is most likely to be found at a given moment in time. Each orbital can hold a maximum of two electrons.

anion

negatively charged atom

Pauli exclusion principle

no two electrons in the same atom can have the same set of four quantum numbers (n, l, ml, and ms)

Cation

positively charged atom

subatomic particles

protons, neutrons, electrons

Heisenberg uncertainty principle

states that it is not possible to know precisely both the velocity and the position of a particle at the same time If we want to assess the position of an electron, the electron has to stop (thereby removing its momentum); if we want to assess its momentum, the electron has to be moving (thereby changing its position).

Hund's rule (crowded bus rule) , repulsion

states that single electrons with the same spin (parallel spins) must occupy each equal-energy orbital before additional electrons with opposite spins can occupy the same orbitals the basis for this preference is electron _______: electrons in the same orbital tend to be closer to each other and thus repel each other more than electrons placed in different orbitals.

lanthanide series elements

the f-block elements with atomic numbers 58 through 71

electron configuration, 4, second, second

the first number denotes the principal energy level the letter designates the subshell the superscript gives the number of electrons in that subshell. For example, 2p4 indicates that there are _____ electrons in the _____ (p) subshell of the ________principal energy level.

n + l rule

the lower the sum of the values of the first and second quantum numbers (n + l), the lower the energy of the subshell. -This determines which subshell (5s or 4d) fills first If two subshells possess the same n + l value, the subshell with the lower n value has a lower energy and will fill with electrons first. Add up the principle quantum number and the angular momentum quantum number to see which one is filled first. For example 5d is filled after 6s because N = 5 & l = 2 so 5+ 2 = 7 while n = 6 & l = 0 so 6 + 0 = 6 6s will fill first bc it is lower energy

1, 2, 3

the n-value tells you the number of possible subshells. Therefore, there's only ___ subshell (l = 0) in the first principal energy level; there are ___ subshells (l = 0 and 1) within the second principal energy level; there are ____ subshells (l = 0, 1, and 2) within the third principal energy level, and so on.

atomic number

the number of protons in the nucleus of an atom

Aufbau Principle

the rule that electrons occupy the orbitals of lowest energy first

Mass number (A)

the sum of the number of neutrons and protons in an atomic nucleus

atomic weight

the weighted average mass of the atoms in a naturally occuring element Bromine, for example, is listed in the periodic table as having a mass of 79.9 amu. This is an average of the two naturally occurring isotopes, bromine-79 and bromine-81, which occur in almost equal proportions. There are no bromine atoms with an actual mass of 79.9 amu.

Planck's equation

∆E = hf, electromagnetic energy is quantized and only comes in discrete units related to the wave frequency. H= 6.6x10^-34 J*s

spin quantum number

+1/2 or -1/2 The spin quantum number indicates that the number of possible spin states for an electron in an orbital is

electron charge ( -1 e)

- 1.6 x 10^-19 C

Maximum number of electrons within a subshell

- 4l+2 - s = 2; p = 6; d = 10 ; f = 14

3

All elements in period ____ (starting with sodium) and below may accept electrons into their d subshell, which allows them to hold more than eight electrons in their valence shell. This allows them to violate the octet rule.

Electron shell

All orbitals with the same value of n example shell = 3s and 3p and 3d altogether like the energy level, n

Electron Subshell

All orbitals with the same value of n and l example: 3d

2.4*10^5

An electron returns from an excited state to its ground state, emitting a photon at λ = 500 nm. What would be the magnitude of the energy change if one mole of these photons were emitted? (Note:h=6.626×10-34 J*s) A. 3.98 × 10-21 J B. 3.98 × 10-19 J C. 2.39×103 J D. 2.39×105 J E = HC/wavelength E = (6.626*10^-34 J*s)*(3*10^8 m/s) / (500 * 10^-9 m) E = (19.8 * 10^-26 J) / (500 * 10^-9 m) E = (19.8 * 10^-26 J) / (5 * 10^-7 m) E = 3.98 x 10^-19 J * 6.02*10^23 atoms/mole E = 24 * 10^4 J/mole E = 2.4 * 10^5

ferrofluid

An example of a paramagnetic substance

AHED

As electrons go from a lower energy level to a higher energy level, they get _______(Acronym): • Absorb light • Higher potential • Excited • Distant (from the nucleus)

paramagnetic

Atom or substance containing unpaired electrons and is consequently attracted by a magnet. These atoms with unpaired electrons will orient their spins in alignment with the magnetic field, thus being attracted Remember that paramagnetic means that a magnetic field will cause PARALLEL spins in unpaired electrons and there- fore cause an attraction.

chemical properties

Because isotopes have the same number of protons and electrons, they generally exhibit similar ______ ______

speed of light equation

C = λf (speed of light = wavelength x frequency); speed of light in vacuum is 3.0 x 10^8 m/s

neutral oxygen has 2 paired and 2 unpaired, ionized oxygen has 3 paired electrons

Compare the paired and unpaired electrons in the orbital diagram for a neutral oxygen (O) atom and an O2- ion.

parallel (reason: their spins are aligned in the same direction (ms = + 1/2 for both species).

Consider the two sets of quantum numbers shown in the table, which describe two different electrons in the same atom. n l ml ms ------------------- 2 1 1 +1/2 3 1 -1 +1/2 ------------------- Which of the following terms best describes these two electrons? A. Parallel B. Opposite C. Antiparallel D. Paired

28 p, 28 e, 30 n and 28 p, 26 e, and 32 n

Determine the number of protons, neutrons, and electrons in a nickel-58 atom and in a nickel-60 +2 cation.

energy of the electron equation

E = -(Rh/n^2) Rh = Rydberg's constant = 2.18 x 10^-18 (J/electron) n = quantum number E = energy (J)

41.15 amu

Element Q consists of three different isotopes: A, B, and C. Isotope A has an atomic mass of 40 amu and accounts for 60 percent of naturally occurring Q. Isotope B has an atomic mass of 44 amu and accounts for 25 percent of Q. Finally, isotope C has an atomic mass of 41 amu and accounts for 15 percent of Q. What is the atomic weight of element Q?

protons

Elements are defined by the number of _______ they contain

E = hc/wavelength

Energy of a Photon Formula

2l + 1, n^2, 2n^2

For any value of l, there will be ______ possible values for ml. For any n, this produces ____ orbitals. For any value of n, there will be a maximum of ____electrons (two per orbital).

54

How many total electrons are in a 133Cs cation? A. 54 B. 55 C. 78 D. 132

400 nm

If an electron emits 3 eV of energy, what is the corresponding wavelength of the emitted photon? (Note: 1 eV = 1.60 × 10-19 J, h = 6.626 × 10-34 J . s) E = hc/wavelength wavelength = hc/E wavelength = (6.626*10^-34 J*s)(3*10^8 m/s) / (3)(1.6*10^-19 J) wavelength = 4*10^-7 meters or ______

increase in angular momentum

In angular momentum L=nh/2pi an increase in quantum number causes a ___________ (the greater the quantum number, the greater the radius of the electron or its distance from the nucleus since n = distance/shell, thus angular momentum increases.

spectroscopic notation

A shorthand version for representing electron configurations; i.e. 1s²2s²2p⁶ shorthand representation of the principal (n) and azimuthal (l) numbers l = 0 --> s l = 1 --> p l = 2 --> d l = 3 --> f Principal number remains a number Azimuthal number is designated by a letter l=0 subshell is called s; Group 1-2 plus helium, 1s^1-7s^2 l=1 subshell is called p; Group 3-8 minus helium 2p^1-7p^6 l-2 subshell is called d; middle gap 3d^1- 6d^10 l-3 subshell is called f; bottom two rows 4f^1-5f^14 s, p, d, f suk, pusy, dik, fuk example; electron in shell n=4 and subshell l=2 is said to be in the 4d subshell

Rydberg unit of energy

2.18 x 10^-18 J/electron the photo is the energy of the electron equation

1 amu =

1.66 x 10^-24 g

the first five orbitals

1s, 2s, 2px, 2py, and 2pz