notebook lm flashcards

According to the rules for significant figures, zeros located between nonzero digits are _.

Significant

How are zeros to the left of the first nonzero digit treated in terms of significant figures?

They are not significant

Zeros to the right of the last nonzero digit are significant only if the number contains a _.

Decimal point

What is the relationship between mass number (A), protons p⁺, and neutrons n⁰?

the sum of protons and neutrons

What are isotopes?

Atoms with the same number of protons but a different number of neutrons.

If the average atomic mass of chlorine is 35.45 amu and its two isotopes are ³⁵Cl and ³⁷Cl, which isotope is more abundant?

The ³⁵Cl isotope is more abundant because the average mass is closer to 35.

What is the first step in solving a stoichiometry problem involving a limiting reactant?

Identify the limiting reactant by comparing the mole ratio of reactants to the stoichiometric ratio.

How is the percent yield of a chemical reaction calculated?

Actual Yield/Theoretical Yield x 100

What is the definition of molarity (M)?

moles of solute per liter of solution M=mol/V

What is the formula used for solution dilution calculations?

M₁V₁=M₂V₂

In the electromagnetic spectrum, what is the relationship between frequency, energy, and wavelength?

High frequency corresponds to high energy and shorter wavelength.

According to the Bohr model, an electron moving from a higher energy level (e.g., n=4) to a lower one (n=2) will _ energy.

Emit.

In the Bohr model, transitions between stationary states that are closer together produce __________ light of energy and

___________ wavelength.

Lower; longer.

What does the principal quantum number, n, describe?

It describes the main energy level or shell of an electron.

The angular momentum quantum number, l, defines the _ of an orbital.

Shape

What is the range of possible values for the magnetic quantum number, m_l, given an angular momentum quantum number, l=1?

-1 to 1, including 0.

How does atomic size generally change when moving from left to right across a period in the periodic table?

decreases due to an increase in the number of protons pulling electrons in.

How does atomic size generally change when moving down a group in the periodic table?

Atomic size increases because each period adds a new electron energy level.

Define first ionization energy.

the energy required to remove the first and most loosely held electron from a neutral atom

How does first ionization energy generally trend across a period (left to right)?

It increases.

An incomplete octet is a common exception to the octet rule for elements like _.

B,Be, Al

What is an expanded octet?

An exception to the octet rule where a central atom in a molecule has more than eight electrons in its valence shell.

Elements in the third period and below, such as Phosphorus (P) and Sulfur (S), can have an _ octet.

Expanded.

What is electronegativity?

A measure of the ability of an atom in a chemical compound to attract electrons.

How does electronegativity trend on the periodic table?

It increases from left to right across a period and decreases down a group.

A bond where electrons are shared unequally between two atoms is called a _.

Polar covalent bond.

A molecule like CCl₄ has polar bonds, but is a nonpolar molecule. Why?

The symmetrical tetrahedral geometry causes the individual bond dipoles to cancel each other out.

In VSEPR theory, what is the molecular geometry of a molecule with a central atom that has 3 bonding pairs and 1 lone pair, such as ammonia?

Trigonal pyramidal.

What is the approximate H-O-C bond angle in a molecule like epinephrine where the oxygen atom has two lone pairs?

<109.5

How does bond length change as the number of bonds between two carbon atoms increases from a single to a triple bond?

it decreases

A double bond consists of one ____ bond and one _____ bond.

Sigma and pi.

What type of hybridization is associated with a central atom that has a trigonal planar electron geometry, like in BF₃

sp²

A flask that feels hot to the touch during a chemical reaction indicates an _________ process, where the system ________ energy.

Exothermic; releases.

For an exothermic process, the sign of the change in enthalpy ΔH is _.

Negative (<0)

What is the name for the weak intermolecular forces caused by temporary fluctuations in electron distribution in atoms and molecules?

London dispersion forces.

What type of intermolecular force exists between all polar molecules?

Dipole-dipole interactions.

Hydrogen bonding is a special, strong type of dipole-dipole interaction that occurs when hydrogen is bonded to which three elements?

Nitrogen (N), Oxygen (O), or Fluorine (F).

As the strength of intermolecular forces in a substance increases, what happens to its boiling point?

it increases

As the strength of intermolecular forces in a substance increases, what happens to its vapor pressure?

it decreases

What is the definition of specific heat capacity (C)?

The amount of heat required to raise the temperature of one gram of a substance by one degree Celsius.

What is the formula to calculate the heat absorbed or released by a substance undergoing a temperature change?

q = mcΔT

During a phase change, such as melting or boiling, the temperature of the substance _.

Remains constant.

The formula q = n\ΔH_vap is used to calculate the heat required for what process?

Vaporization (boiling).

Hess's Law states that if a reaction is carried out in a series of steps, the ∆H for the overall reaction is the _ of the enthalpy changes for the individual steps.

Sum

How is the standard enthalpy of reaction ΔHrxn∘​=∑nΔHf∘​(products)−∑mΔHf∘​(reactants) calculated using standard enthalpies of formation ∆Hf∘​

ΔHrxn∘​=∑nΔHf∘​(products)−∑mΔHf∘​(reactants)

What is the standard enthalpy of formation Δ°_f for any pure element in its standard state?

Zero.

What is the relationship between pressure and volume for a gas at constant temperature and moles, according to Boyle's Law?

They are inversely proportional P1V1 = P2V2

According to Charles's Law, the volume and absolute temperature of a gas are _ proportional at constant pressure.

Directly.

What is the ideal gas law equation?

PV = nRT

What is the first postulate of the Kinetic Molecular Theory (KMT) of gases?

Particles of a gas are in constant, random motion and undergo elastic collisions with each other and the container walls.

According to the KMT, the volume of the gas particles themselves is considered _ compared to the volume of the container.

Negligible (the gas is mostly empty space).

The third postulate of KMT states that pressure is exerted when gas particles _.

Hit the sides of the container.

The fourth postulate of KMT assumes that gas particles do not _ with each other in ideal conditions.

Interact (there are no intermolecular forces).

The fifth postulate of KMT states that the average kinetic energy of gas particles is directly proportional to the _.

Absolute temperature (in Kelvin).

At the same temperature, will lighter gas molecules move faster or slower on average than heavier gas molecules?

faster

What is effusion?

The process of a gas escaping from a container into a vacuum through a small hole.

Under what two conditions do real gases most deviate from ideal behavior?

High pressure and low temperature.

Why do real gases deviate from ideal behavior at high pressure?

The volume of the gas particles is no longer negligible, and intermolecular forces become significant as particles are forced closer together.

Why do real gases deviate from ideal behavior at low temperature?

Particles move slower, allowing intermolecular forces to become significant and cause interactions.

A real gas behaves most like an ideal gas under conditions of ________ temperature and _______ pressure.

High; low.

What is the chemical formula for the ionic compound formed from iron (III) and carbonate ?

Fe₂(CO₃)³

What are spectator ions in a chemical reaction?

Ions that do not participate directly in the reaction and appear unchanged on both the reactant and product sides of the complete ionic equation.

What is a strong electrolyte?

A substance that dissolves in water and completely dissociates into ions, conducting electricity well.

In the reaction 2 Na (s)+2 H_2​O (l)⟶2 NaOH (aq)+H_2​ (g), what is the reducing agent?

Na because it is oxidized and loses electrons

For an isoelectronic series (e.g., O^2-, F^-, Na⁺, Mg²⁺) how does the ionic radius change as the nuclear charge (atomic number) increases?

decreases because the increasing number of protons pulls the same number of electrons more tightly.

Which set of elements is arranged in order of increasing electronegativity: O, Li, K, B?

K < Li < B < O

Which of the following bonds is the most polar: C-H, N-H, O-H, or F-H?

F-H, due to the largest difference in electronegativity between the two atoms.

How many sigma ∂ and pi π bonds are in the structure of epinephrine?

26 sigma bonds and 3 pi bonds.

True or False: A carbon-carbon double bond is longer than a carbon-carbon single bond.

False

In the reaction where 6.0 moles of ammonia react with 8.0 moles of oxygen 4 NH₃​+5 O_2​→4 NO+6 H_2​O, which is the excess reactant?

O₂

What is an excited-state electronic configuration?

where an electron has absorbed energy and jumped to a higher energy orbital than it would occupy in the ground state.