CHEM 1153 Exam 1 Review

These flashcards cover key concepts, quantum numbers, atomic properties, and calculations relevant to the exam material in chemistry.

How are atomic orbitals designated using the principal quantum number (n) and azimuthal quantum number (l)?

Atomic orbitals are designated by combining the principal quantum number (n) with a letter corresponding to the azimuthal quantum number (l) (e.g., l=0 is 's', l=1 is 'p', l=2 is 'd', l=3 is 'f').

What are the four quantum numbers and what do they generally describe?

The four quantum numbers are: principal (n) which describes the electron's energy level and size of the orbital; azimuthal (l) for the shape of the orbital; magnetic (ml) for the orientation of the orbital in space; and electron spin (ms) for the intrinsic angular momentum of an electron.

Describe the relationship between the frequency, wavelength, and energy of a photon.

The frequency (
u) and wavelength (\lambda) of a photon are inversely proportional (c = \lambda\nu). The energy (E) of a photon is directly proportional to its frequency (E = h\nu), where h is Planck's constant. Thus, higher frequency means shorter wavelength and higher energy.

Explain electron transitions between atomic energy levels and their relation to light emission or absorption.

When an electron transitions between discrete energy levels in an atom, a photon is either emitted (if moving to a lower energy level) or absorbed (if moving to a higher energy level). The energy of the photon corresponds precisely to the energy difference between the levels, determining its specific wavelength or frequency.

What are the general periodic trends for atomic radius?

Atomic radius generally decreases across a period (left to right) due to increasing effective nuclear charge, and increases down a group due to the addition of new electron shells (higher n).

What are the general periodic trends for first ionization energy?

First ionization energy generally increases across a period (left to right) due to greater attraction between the nucleus and valence electrons, and decreases down a group because valence electrons are further from the nucleus and more shielded.

Define core electrons and valence electrons.

Core electrons are those in filled inner shells which are generally unreactive. Valence electrons are the electrons in the outermost principal energy level and are primarily involved in chemical bonding.

How is the electron configuration of a transition metal cation determined?

When forming a cation from a neutral transition metal atom, electrons are first removed from the (n)s orbitals, and then from the (n-1)d orbitals if more electrons need to be removed to achieve the desired charge.

State the Pauli exclusion principle.

The Pauli exclusion principle states that no two electrons in an atom can have the exact same set of four quantum numbers (n, l, ml, ms).

What makes an atom or ion paramagnetic or diamagnetic?

An atom or ion is paramagnetic if it contains one or more unpaired electrons, causing it to be attracted to an external magnetic field. It is diamagnetic if all its electrons are paired, causing it to be weakly repelled by a magnetic field.

How can the identity of an element be determined from its ground-state electron configuration?

The identity of an element is determined by its atomic number (Z), which is equal to the total number of electrons in a neutral atom's ground-state electron configuration.

What defines a chemical compound?

A chemical compound is a substance formed when two or more different chemical elements are chemically bonded together in a fixed ratio, resulting in properties distinct from its constituent elements.

Distinguish between a physical change and a chemical change in matter.

A physical change alters the form or appearance of a substance but not its chemical composition (e.g., phase changes, dissolving). A chemical change results in the formation of new substances with different chemical properties (e.g., combustion, oxidation).

Define a chemical property and give general examples.

A chemical property describes a substance's potential to undergo a specific chemical change. Examples include flammability, reactivity with acids/bases, and oxidation potential.

How is density defined and what is its typical formula?

Density (\rho) is an intrinsic physical property of matter defined as the mass (m) per unit volume (V), expressed by the formula \rho = m/V. It indicates how much mass is contained in a given space.

What is the significance of Avogadro's number in chemistry?

Avogadro's number (6.022 \times 10^{23}) is the number of constituent particles (atoms, molecules, ions, etc.) in one mole of any substance. It serves as a conversion factor between the macroscopic quantity of moles and the microscopic number of particles.

How is the mass of a large number of molecules calculated?

The mass of a given number of molecules can be calculated by first converting the number of molecules to moles using Avogadro's number, and then multiplying by the molar mass of the substance (in g/mol).

How is the molecular (or formula) mass of a compound calculated?

The molecular (or formula) mass of a compound is calculated by summing the average atomic masses of all atoms present in its chemical formula. For ionic compounds, it's often referred to as formula mass.

How is the charge of an ion determined in a neutral ionic compound?

In a neutral ionic compound, the sum of the charges of all cations and anions must be zero. If the charge of one ion type is known, the charge of the other can be determined by balancing the overall charge.

How are the identity and charge of an ion determined from the number of protons, neutrons, and electrons?

The number of protons determines the atomic number (Z) and thus the element's identity. The charge of an ion is determined by the difference between the number of protons and electrons (charge = protons - electrons). Neutrons differentiate isotopes but not the element or charge.