Chemistry Exam Review - Matter, Measurement, and Atomic Structure

Flashcard practice set derived strictly from the chemistry exam-focused quizlet notes covering matter classifications, intensive/extensive properties, SI units, dimensional analysis, scientific notation, energy types, atomic history, isotopes, ions, chemical laws, and periodic table organization.

What is the definition of matter?

Anything that has mass and occupies space.

What is the difference between an element and a compound?

An element is a pure substance made of only one type of atom that cannot be broken down chemically, whereas a compound is made of two or more different elements chemically bonded together.

What are the three state examples of solutions (homogeneous mixtures) provided in the notes?

Air (gas solution), salt water (liquid solution), and brass (solid solution).

Why is $O_2$ classified as an element while $H_2O$ is classified as a compound?

$O_2$ is an element because it contains only oxygen atoms, whereas $H_2O$ is a compound because it contains both hydrogen and oxygen.

What is the difference between physical properties and chemical properties?

A physical property can be observed or measured without changing the substance's identity, while a chemical property describes a substance's ability to undergo a chemical change.

How do you distinguish between a physical change and a chemical change?

In a physical change, the substance's identity remains the same; in a chemical change, one or more new substances form.

In chemical reaction notation ($\text{Reactants} \rightarrow \text{Products}$), what is located on each side of the arrow?

Reactants are on the left side of the arrow, and products are on the right side.

What is the distinction between intensive and extensive properties?

An intensive property does not depend on the amount of substance present (e.g., density, temperature), whereas an extensive property depends on the amount of substance present (e.g., mass, volume).

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

Meter ($m$) for length, kilogram ($kg$) for mass, second ($s$) for time, Kelvin ($K$) for temperature, and mole ($mol$) for amount of substance.

What physical multipliers do the metric prefixes Kilo-, Centi-, Milli-, Micro-, and Nano- represent?

Kilo- is $10^3 = 1,000$ times the base unit; Centi- is $10^{-2} = 0.01$ times the base unit; Milli- is $10^{-3} = 0.001$ times the base unit; Micro- is $10^{-6}$ times the base unit; Nano- is $10^{-9}$ times the base unit.

What is the main rule of dimensional analysis?

Arrange conversion factors so the units you do not want cancel, leaving the desired unit.

How are $4500$ and $0.0045$ expressed in scientific notation?

$4500$ is written as $4.5 \times 10^3$, and $0.0045$ is written as $4.5 \times 10^{-3}$.

What does a positive exponent versus a negative exponent represent in scientific notation?

A positive exponent usually indicates a number greater than $1$, while a negative exponent usually indicates a number between $0$ and $1$.

What is the Law of Conservation of Energy?

Energy cannot be created or destroyed; it can only be transferred or transformed.

What are the common steps of the scientific method in order?

Question/observation \rightarrow hypothesis \rightarrow experiment \rightarrow data analysis \rightarrow conclusion \rightarrow communication.

What is the difference between a scientific law and a scientific theory?

A scientific law is a statement describing what happens in nature, whereas a scientific theory is a well-supported explanation of how or why something happens.

What is the formula for density, and what is the density of a sample with mass $20\,g$ and volume $5\,mL$?

Density formula is $D = \frac{m}{V}$. For $20\,g$ and $5\,mL$, density = $4\,g/mL$.

What are the formulas for converting between Celsius, Fahrenheit, and Kelvin?

$^\circ\text{F} = (^\circ\text{C} \times \frac{9}{5}) + 32$, $^\circ\text{C} = (^\circ\text{F} - 32) \times \frac{5}{9}$, $K = ^\circ\text{C} + 273.15$, and $^\circ\text{C} = K - 273.15$.

What are the key rules for determining if zeros are significant figures?

Leading zeros are never significant; zeros between nonzero digits are significant; trailing zeros after a decimal point are significant.

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

For multiplication/division, the answer has the same number of significant figures as the measurement with the fewest significant figures. For addition/subtraction, the answer has the same number of decimal places as the measurement with the fewest decimal places.

What are the answers for $2.5 \times 3.42$ and $12.11 + 3.2$ using correct significant figures?

$2.5 \times 3.42 = 8.6$ (2 significant figures) and $12.11 + 3.2 = 15.3$ (1 decimal place).

How do accuracy and precision differ?

Accuracy is how close a measurement is to the accepted or true value, whereas precision is how close repeated measurements are to each other.

What are the relative charges and locations of protons, neutrons, and electrons?

Protons have a charge of $+1$ and are in the nucleus; neutrons have a charge of $0$ and are in the nucleus; electrons have a charge of $-1$ and are outside the nucleus.

How do Dalton's, Thomson's, and Rutherford's atomic models differ?

Dalton's solid sphere model viewed atoms as tiny, indivisible spheres; Thomson's plum pudding model viewed electrons embedded in a positive substance; Rutherford's nuclear model showed atoms as mostly empty space with a small, dense, positively charged nucleus.

What is the difference between atomic number and mass number?

Atomic number is the number of protons in an atom (identifying the element), while mass number is the total number of protons plus neutrons.

How many protons, neutrons, and electrons are present in a neutral atom with atomic number $17$ and mass number $37$?

It contains $17$ protons, $20$ neutrons ($37 - 17 = 20$), and $17$ electrons (Chlorine, $Cl$).

How do cations and anions form, and how many electrons do $Na^+$ and $Cl^-$ contain?

Cations are positively charged ions formed by losing electrons ($Na^+$ has $10$ electrons); anions are negatively charged ions formed by gaining electrons ($Cl^-$ has $18$ electrons).

What are isotopes, and how do Carbon-12 and Carbon-14 differ in subatomic particles?

Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons. Carbon-12 has $6$ protons and $6$ neutrons, while Carbon-14 has $6$ protons and $8$ neutrons.

What is average atomic mass, and what is its equation?

Average atomic mass is the weighted average of naturally occurring isotopes of an element. Formula: $\text{Average atomic mass} = \sum (\text{isotope mass} \times \text{fractional abundance})$.

If an element has an isotope of $10\,amu$ at $75\%$ abundance and an isotope of $11\,amu$ at $25\%$ abundance, what is its average atomic mass?

$(10)(0.75) + (11)(0.25) = 10.25\,amu$.

What are the three main laws of chemical combination mentioned in the transcript?

Law of Conservation of Mass (mass is neither created nor destroyed), Law of Definite Proportions (a compound always contains the same elements in the same fixed mass ratio), and Law of Multiple Proportions (combining masses in multiple compounds are related by small whole-number ratios).

What is the formula for percent composition?

$\%\,\text{element} = \left(\frac{\text{mass of element in } 1\,\text{mol compound}}{\text{molar mass of compound}}\right) \times 100$.

How many groups and periods are on the periodic table?

There are $18$ groups (vertical columns) and $7$ periods (horizontal rows).

What group names correspond to Groups 1, 2, 17, and 18 on the periodic table?

Group 1 (except hydrogen) = Alkali metals; Group 2 = Alkaline earth metals; Group 17 = Halogens; Group 18 = Noble gases.

Which elements are categorized as coinage metals?

Copper ($Cu$), silver ($Ag$), and gold ($Au$).

Where are metals, nonmetals, and metalloids located on the periodic table, and what are six common metalloids?

Metals are mostly on the left and center, nonmetals are mostly on the upper right side, and metalloids lie along the stair-step line. The six common metalloids are $B$, $Si$, $Ge$, $As$, $Sb$, and $Te$.