Chemistry Foundations, Atomic Theory, Nomenclature, and Stoichiometry

Comprehensive flashcards for Zumdahl Chemistry 10th Edition covering chemical foundations, atomic structure, periodic table trends, chemical nomenclature, formulas, and stoichiometry.

What is the key difference between qualitative observations and quantitative observations?

Qualitative observations do not involve numbers (e.g., describing color or state), whereas quantitative observations (measurements) involve both a number and a unit.

In the scientific method, how does a theory (model) differ from a natural law?

A natural law is a summary of observed, measurable behavior (what happens), whereas a theory (model) is a set of tested hypotheses that provides an overall explanation of why nature behaves in a certain way.

What are the fundamental SI base units for mass, length, time, temperature, and amount of substance?

Mass is measured in kilograms ($kg$), length in meters ($m$), time in seconds ($s$), temperature in kelvins ($K$), and amount of substance in moles ($mol$).

What are the exponential values associated with the SI prefixes mega-, kilo-, centi-, milli-, micro-, and nano-?

Mega- ($M$) is $10^6$, kilo- ($k$) is $10^3$, centi- ($c$) is $10^{-2}$, milli- ($m$) is $10^{-3}$, micro- ($μ$) is $10^{-6}$, and nano- ($n$) is $10^{-9}$.

What metric volume units are exactly equivalent to $1\,L$ and $1\,mL$?

$1\,L$ is equal to $1\,dm^3$, and $1\,mL$ is equal to $1\,cm^3$.

When reporting a measurement in science, which digits must be recorded?

Record all certain digits (numbers that remain identical regardless of who measures) plus the first uncertain digit (an estimated number).

What is the meniscus, and where is liquid volume read on a buret?

The meniscus is the curved upper surface of a liquid; volume is read at the bottom of the liquid curve.

What is the distinction between precision and accuracy in scientific measurements?

Accuracy refers to the agreement of a particular value with the true value, while precision refers to the degree of agreement among several measurements of the same quantity (reproducibility).

How do random errors differ from systematic errors?

Random error (intermediate error) has an equal probability of being high or low and occurs in estimating the last digit. Systematic error (determinate error) occurs in the same direction each time, being consistently high or consistently low.

What are the rules for determining whether zeros are significant figures?

Leading zeros (preceding all nonzeros) never count as sig figs. Captive zeros (between nonzeros) always count. Trailing zeros (at the right end) are significant only if the number contains a decimal point.

What are the significant figure rules for multiplication/division versus addition/subtraction?

For multiplication and division, the result has the same number of sig figs as the term with the fewest sig figs. For addition and subtraction, the result has the same number of decimal places as the least precise measurement used.

What formulas are used to convert temperature between Celsius ($^\circ C$), Kelvin ($K$), and Fahrenheit ($^\circ F$)?

Celsius to Kelvin: $K = ^\circ C + 273.15$. Fahrenheit to Celsius: $^\circ C = (^\circ F - 32) \times \frac{5}{9}$. Celsius to Fahrenheit: $^\circ F = ^\circ C \times \frac{9}{5} + 32$.

How is density defined, and why is it considered an intensive property?

Density is defined as mass divided by volume ($d = \frac{m}{V}$). It is an intensive physical property because its value remains constant for a given pure material regardless of sample size.

What are the physical characteristics of the solid, liquid, and gas states of matter?

A solid is rigid with a fixed volume and shape. A liquid has a definite volume but no specific shape, assuming the shape of its container. A gas has no fixed volume or shape, taking the volume and shape of its container, and is highly compressible.

What is the difference between a homogeneous mixture and a heterogeneous mixture?

A homogeneous mixture (solution) has visibly indistinguishable parts and uniform composition throughout. A heterogeneous mixture has visibly distinguishable parts and distinct phases.

How does a physical change differ from a chemical change?

A physical change involves a change in the form or physical state of a substance without altering its chemical composition (e.g., freezing water). A chemical change involves changing a substance into new substances with different compositions by reorganizing how atoms are attached.

According to this flowchart, how is matter categorized based on variable composition and visibly distinguishable parts?

Matter with variable composition is a mixture (heterogeneous if visibly distinguishable, homogeneous if not). Matter with constant composition is a pure substance (compound if it contains various types of atoms, element if it does not).

What fundamental chemical law was verified by Antoine Lavoisier?

The Law of Conservation of Mass, which states that mass is neither created nor destroyed in a chemical reaction.

What is Joseph Proust's Law of Definite Proportion?

A given chemical compound always contains exactly the same proportion of elements by mass regardless of the source or sample size.

What is John Dalton's Law of Multiple Proportions?

When two elements form a series of compounds, the ratios of the masses of the second element that combine with $1\,g$ of the first element can always be reduced to small whole numbers.

What are the main postulates of Dalton's Atomic Theory?

1) Elements are composed of tiny particles called atoms. 2) Atoms of a given element are identical. 3) Atoms of different elements differ fundamentally. 4) Compounds form when atoms of different elements combine in fixed relative numbers. 5) Chemical reactions involve atom reorganization; atoms themselves are unchanged.

What did J. J. Thomson discover using cathode-ray tubes, and what value did he determine?

Thomson postulated that cathode rays are streams of negatively charged particles (electrons) and determined the electron's charge-to-mass ratio to be $\frac{e}{m} = -1.76 \times 10^8\,C/g$.

What was J. J. Thomson's Plum Pudding Model of the atom?

A model representing the atom as a diffuse, spherical cloud of positive charge with negatively charged electrons embedded randomly throughout it.

What were Robert Millikan's key findings from his charged oil-drop experiment?

Millikan determined the magnitude of the charge on a single electron ($1.60 \times 10^{-19}\,C$) and calculated the mass of an electron to be $9.11 \times 10^{-31}\,kg$.

How did Ernest Rutherford's gold foil experiment alter the model of the atom?

By directing $\alpha$ particles at thin metal foil and observing that some were deflected at large angles, Rutherford disproved the plum pudding model and proposed the nuclear atom—a dense center of positive charge (the nucleus) surrounded by electrons moving through mostly open space.

What are the three primary subatomic particles, their relative charges, and their approximate masses?

Proton: charge $1+$, mass $1.673 \times 10^{-27}\,kg$. Neutron: charge $0$, mass $1.675 \times 10^{-27}\,kg$. Electron: charge $1-$, mass $9.109 \times 10^{-31}\,kg$.

In atomic notation $_Z^A X$, what do the symbols $A$ and $Z$ represent?

$A$ represents the mass number (total number of protons plus neutrons), and $Z$ represents the atomic number (number of protons).

What are isotopes?

Atoms of the same element that have the same number of protons (atomic number) but different numbers of neutrons (and thus different mass numbers).

How do cations and anions form from neutral atoms?

A cation is a positive ion formed when a neutral atom loses one or more electrons. An anion is a negative ion formed when a neutral atom gains one or more electrons.

What are the common family names and characteristic ionic charges for Group 1A, Group 2A, Group 7A, and Group 8A elements?

Group 1A: Alkali metals (form $1+$ cations). Group 2A: Alkaline earth metals (form $2+$ cations). Group 7A: Halogens (form $1-$ anions). Group 8A: Noble gases (monatomic gases with little chemical reactivity).

How are Type I and Type II binary ionic compounds named?

Type I compounds (fixed-charge metals) are named as [cation element name] + [anion root + -ide]. Type II compounds (metals forming multiple charges) specify the cation charge using Roman numerals in parentheses: [cation element name](Roman numeral) + [anion root + -ide].

What system is used for naming Type III binary covalent compounds?

Formed between two nonmetals: name the first element using its full name (with prefixes di-, tri-, etc., except mono- is omitted for the first element), followed by the second element named as an anion using prefixes to denote quantity.

How do prefixes and suffixes indicate the number of oxygen atoms in a series of oxyanions?

For two oxyanions: the one with fewer oxygen atoms ends in -ite, and the one with more ends in -ate. For four oxyanions: hypo- + root + -ite (fewest O), root + -ite, root + -ate, per- + root + -ate (most O).

What are the rules for naming acids without oxygen versus acids containing oxyanions?

Acids without oxygen use the prefix hydro- + anion root + -ic acid (e.g., $HCl(aq)$ is hydrochloric acid). Acids with oxyanions change an -ate ending to -ic acid and an -ite ending to -ous acid.

What atom serves as the modern standard for atomic mass units ($u$)?

Carbon-12 ($^{12}C$), which is assigned a mass of exactly $12$ atomic mass units ($u$).

How is the average atomic mass of a naturally occurring element calculated from isotopic data?

By summing the product of each isotope's fractional abundance and its isotopic mass: $\text{Average Mass} = \sum_i (\text{fractional abundance}_i \times \text{isotopic mass}_i)$

How is a mole ($mol$) defined, and what is Avogadro's number?

A mole is the amount of substance containing as many particles as there are carbon atoms in exactly $12\,g$ of pure $^{12}C$. Avogadro's number is $6.022 \times 10^{23}$ particles per mole.

What is molar mass, and how is it calculated for a compound?

Molar mass is the mass in grams of one mole of a substance ($g\,mol^{-1}$). It is calculated by summing the atomic masses of all constituent atoms in the compound's chemical formula.

How is the mass percent of an element in a compound calculated?

$$\text{Mass Percent} = \frac{\text{mass of element in } 1\text{ mol of compound}}{\text{molar mass of compound}} \times 100\%$$

What is the relationship between a compound's empirical formula and its molecular formula?

The empirical formula represents the simplest whole-number ratio of atoms in a compound. The molecular formula is the exact formula, expressed as $(\text{empirical formula})_n$, where $n = \frac{\text{molar mass}}{\text{empirical formula mass}}$.

Why is the mole referred to as the 'universal converter' in chemical equations?

Because coefficients in a balanced chemical equation represent ratios of molecules or moles, not mass in grams. Experimental measurements (mass, volume) must be converted into moles to use stoichiometric ratios.

Why is changing subscripts strictly forbidden when balancing a chemical equation?

Changing subscripts alters the chemical identity and properties of the compound (e.g., changing $H_2O$ to $H_2O_2$ turns water into hydrogen peroxide). Equations must be balanced only by changing coefficients.

What is a limiting reactant (limiting reagent)?

The reactant that is completely consumed first in a chemical reaction, thereby limiting the maximum amount of product that can be formed.

What is an excess reagent?

The reactant that remains leftover after the limiting reactant is completely consumed and the chemical reaction stops.

How are theoretical yield, actual yield, and percent yield related?

Theoretical yield is the maximum amount of product predicted from complete consumption of the limiting reactant. Actual yield is the amount of product experimentally obtained. Percent yield is calculated as: $\text{Percent Yield} = \frac{\text{Actual Yield}}{\text{Theoretical Yield}} \times 100\%$