Chapters 1-14, 18 Flashcards
What determines the average kinetic energy of a gas?
Temperature
What is the relationship of average gas speed and its molar mass?
described by Graham’s law which states that the rate of effusion or diffusion of a gas is inversely proportional to the square root of its molar mass // indicates that lighter gas molecules will have higher root mean square speeds compared to heavier gas molecules, assuming the temperatures of the gases are the same. The relationship highlights how the kinetic energy of gas molecules is related to their mass.
What is the ionization energy for an atom?
- the amount of energy required to remove an electron from an atom in its gaseous state
- typically expressed in energy units kilojoules per mole (kJ/mol)
- factors that affect ionization energy include: nuclear charge, electron shielding, electron0electron repulsion, and distance from nucleus
- generally INCREASES as you move across a PERIOD from left to right 9due to increasing nuclear charge)
- DECREASES as you move down a GROUP (due to increased distance from nucleus and electron shielding) * exceptions apply
What is a dipole-dipole attraction between some covalent molecules?
- dipole-dipole attractions are intermolecular forces that occur between the positive end (or pole) of one polar molecule and the negative end of another polar molecule
- dipole-dipole forces are generally weaker than ionic or covalent bonds but play a crucial role in determining the physical properties of polar substances.
- contribute to overall forces between molecules and affect properties like boiling point, melting point, and solubility
Charles Law
-At constant pressure, the volume of a gas is directly proportional to its absolute temperature
- V1/T1 = V2/T2
Boyles Law
- At constant temperature, the volume of a given amount of gas is inversely proportional to its pressure. In other words, as the pressure on a gas increases, its volume decreases proportionally, and vice versa, provided that the temperature remains constant.
= PV = k where k is a constant
Daltons Law
- states that the total pressure exerted by a mixture of non-reacting gases is equal to the sum of the partial pressures of individual gases in the mixture
- assumes that the gases in the mixture do not chemically react with each other and behave independently
-Ptotal = P1+P2+P3 etc
Ideal Gas Law
- fundamental equation in thermodynamics and chemistry that describes the relationship between the pressure (P in pascals), volume (V, in cubic meters), temperature (T, in kelvins), and amount of substance (n, in moles) of an ideal gas. The Ideal Gas Law is mathematically represented as:
- PV=nRT where:
P is the pressure of the gas,
V is the volume of the gas,
n is the amount of substance (moles) of the gas,
R is the ideal gas constant (8.314 J/(mol·K)),
T is the absolute temperature of the gas in kelvins. - assumes that the gas particles have no volume, do not interact with each other, and experience elastic collisions.
What is the vapor pressure of a substance?
- the measure of the tendency of a substance to evaporate or transition from a liquid or solid state to a vapor or gas state.
What does the value of the vapor pressure depend on?
- based on the idea that molecules in a liquid or solid are in constant motion, and some of them gain enough energy to escape into the vapor phase, it is influenced by temperature, and as the temperature increases, the vapor pressure generally increases because more molecules have sufficient energy to transition into the vapor phase.
- at the boiling point of a substance, its vapor pressure equals atmospheric pressure, causing the liquid to change into vapor throughout the entire volume.
- substances with weaker intermolecular forces typically have higher vapor pressures at a given temperature compared to substances with stronger intermolecular forces.
Define pressure
- a measure of the force exerted per unit area
- P = F/A
- can be defined using units such as atmospheres (atm), millimeters of mercury (mmHg), and torr where: 1 atm = 760 mmHG = 760 torr
What are greenhouse gases?
- gases in Earth’s atmosphere that can trap heat. They allow sunlight to enter the atmosphere freely but prevent some of the heat that the Earth would otherwise radiate back into space from escaping.
- major gases include: methane, carbon dioxide, nitrous oxide, water, and ozone (O3)
What is equilibirum for a reaction and how to know when it is reached?
-when the rate of the forward reaction equals the rate of the reverse reaction
- all reactant and product concentrations are constant at equilibrium.
What is heat of fusion?
- the amount of heat energy required to change a substance from a solid to a liquid state at its melting point, while maintaining constant temperature and pressure
- typically expressed in joules per gram (J/g) or kilojoules per mole (kJ/mol), depending on whether the mass is given in grams or the number of moles.
- is specific to each substance and is a characteristic property of the material. Different substances have different heat of fusion values due to variations in their intermolecular forces
What is electronegativity?
- a measure of the tendency of an atom to attract a bonding pair of electrons in a covalent bond
- a large electronegativity difference between atoms indicates an ionic bond, a small difference a covalent bond, and intermediate differences a polar covalent bond
- fluorine is the MOST electronegative
What are the general trends for electronegativity on the periodic table?
- generally increases across a period from left to right and decreases down a group in the periodic table
- this trend is influenced by factors such as atomic size and effective nuclear charge.
Explain ionic vs covalent bonds and give their difference
Ionic bonds: formed between metal and nonmetal; one atom transfers electrons to another, resulting in the formation of ions. The metal atom loses electrons to become a positively charged cation, and the nonmetal gains those electrons to become a negatively charged anion. There is a big electronegativity difference between atoms involved and typically exist as crystalline structures with a repeating pattern of ions. They are usually solid at room temperature and have high melting and boiling points
Covalent bonds: formed between nonmetals; atoms share electrons to achieve a more stable elctron configuration, which creates a molecular structure. There is a relatively low or no electronegativity difference between the atoms involved. Covalent compounds can exist in various states at room temperature depending on the specific substance and generally have lower melting and boiling points compared to ionic compounds.
overall difference: ionic transfers while covalent shares; Ionic bonds involve the formation of ions (charged particles) Covalent bonds involve the formation of molecules (groups of atoms held together by shared electrons
What radius is larger and why: Cl or Cl-
Cl- is larger because of the electronic configuration resulting from the gain/loss of electrons. A chlorine atom has 7 electrons in outermost while the ion has an additional electron that increases the electron cloud
Different molecular shapes are:
-linear
-trigonal planar
-tetrahedral
-trigonal pyramidal
-bent
What is the VSEPR Theory?
- predicts the geometry based on the repulsion between electron pairs around the central atom.
- Valence Shell Electron Pair Repulsion
What is osmosis?
- the movement of solvent molecules from an area of lower solute concentration to an area of higher solute concentration through a semipermeable membrane. This process occurs until equilibrium is reached, with equal concentrations of solute on both sides of the membrane.
- always occurs down a concentration gradient. Solvent molecules move from an area of lower solute concentration (HYPOTONIC solution) to an area of higher solute concentration (HYPERTONIC solution).
What are colligative properties of a solution?
- vapor pressure depression, boiling point elevation, freezing point depression, and osmotic pressure
- properties are proportional to the molality (moles of solute per kilogram of solvent) of the solution and do not depend on the nature of the solute particles.
What is an alpha particle?
- type of subatomic particle that consists of two protons and two neutrons, which form a helium-4 nucleus
- positive charge of +2
- have high ionization ability but low penetration power
What is a beta particle?
-type of subatomic particle that is emitted during certain types of radioactive decay. There are two types of beta particles: beta-minus (β −) particles and beta-plus (+β) particles. Both types of beta decay involve the transformation of a neutron or a proton into a beta particle
- have higher penetration power than alpha but not as strong as gamma
What is a gammar ray?
- type of electromagnetic radiation, specifically a high-energy photon
- have the shortest wavelength and highest frequency among the electromagnetic spectrum
- high penetration power
- rays can ionize atoms and molecules and can cause damage to living tissues.
- emitted by the nuclei of certain radioactive atoms during nuclear decay processes. They can also be produced in high-energy processes such as nuclear reactions, particle interactions, and certain astrophysical phenomena.
Define the half-life of a radioactive element
- the time it takes for half of a sample of the element to undergo radioactive decay.
- a measure of the stability of a radioactive isotope and is specific to each particular isotope.
- concept is often used to describe the rate at which a radioactive substance decays over time.
What is a Ci (curie) in reference to radiation?
- a unit to measure radiation
- used to quantify the amount of radioactivity in a sample of radioactive material
- defined as the amount of radioactive material in which there are 3.7 × 10¹⁰ disintegrations per second.
What is nuclear fission? Give an example
- a nuclear reaction in which the nucleus of an atom splits into two or more smaller nuclei, along with the release of energy
- often initiated by bombarding the nucleus with a neutron. The released energy is substantial and is accompanied by the emission of additional neutrons
- example is nuclear power plants; utilize controlled nuclear fission reactions to generate electricity. The most common fuel for nuclear power plants is uranium-235
What is a nuclear chain reaction?
- a self-sustaining series of nuclear fission reactions in which the products of one reaction initiate additional reactions. This creates a cascading effect, leading to a continuous release of energy.
What is nuclear waste and radioactive “fall out”?
- also known as radioactive waste, is the byproduct produced during various nuclear processes
- fallout refers to the descent of airborne particles containing radioactive materials to the Earth’s surface after a nuclear explosion or certain nuclear accidents. This fallout can consist of various radioactive isotopes that are released into the atmosphere during the event. The term is commonly associated with nuclear weapons testing and accidents at nuclear power plants.
Where is nuclaer fusion commonly occuring and what is it?
- is the process by which two light atomic nuclei combine to form a heavier nucleus, releasing a large amount of energy
- commonly occurring on the sun
What are some uses of radiation? (know answer to assigned problem at end of the chapter)
- X-rays, cancer treatment, smoke detectors, space exploration, nuclear plants,
