Atoms Firsts

Chem 112- Unit 1

Describe the central focus of chemistry.

Chemistry is the study of the composition, properties, and interactions of matter.

Explain the scientific method in chemistry.

The scientific method involves observation, forming a hypothesis, conducting experiments, and developing a theory or law.

Define the three domains of chemistry.

The three domains of chemistry are macroscopic, microscopic, and symbolic.

How does mass differ from weight?

Mass is the amount of matter in an object, while weight is the force that gravity exerts on that object.

What does the Law of Conservation of Matter state?

The Law of Conservation of Matter states that the amount of matter does not change during a physical or chemical change.

Differentiate between atoms and molecules.

Atoms are the smallest particles of an element that retain its properties, while molecules consist of two or more atoms joined together.

Define pure substances in chemistry.

Pure substances are composed of a single type of particle, and their composition does not vary.

Explain the difference between elements and compounds.

Elements are the simplest forms of matter that cannot be broken down, while compounds are composed of two or more different elements in a fixed proportion.

What are mixtures in chemistry?

Mixtures are composed of two or more types of particles in varying proportions, and their components can be separated by physical processes.

Describe homogeneous mixtures.

Homogeneous mixtures are thoroughly mixed together, resulting in the same composition throughout; they are also called solutions.

What characterizes heterogeneous mixtures?

Heterogeneous mixtures are not thoroughly mixed, leading to different compositions in different regions, often forming layers.

Define physical properties and changes.

Physical properties can be measured or observed without changing the chemical composition of a substance, while physical changes involve changes in physical state.

Explain chemical properties and changes.

Chemical properties are observed when changing the chemical composition of a substance, and chemical changes involve alterations in chemical composition.

Differentiate between intensive and extensive properties.

Intensive properties are independent of the amount of substance (e.g., density), while extensive properties depend on the amount of substance (e.g., mass).

What are the standard base units in the metric system for length, mass, time, temperature, amount of substance, and volume?

Length: meter (m), Mass: gram (g), kilogram (kg), Time: second (s), Temperature: degrees Celsius (°C), Kelvin (K), Amount of substance: mole (mol), Volume: liter (L), cubic meter (m³).

How do prefix multipliers work in the metric system?

Prefix multipliers can increase or decrease the size of the base unit and can be used in front of any metric base unit.

What is the formula for calculating density?

Density is calculated using the formula: Density = mass / volume (g/mL).

How should mass and volume be converted for density calculations?

Mass should be converted to grams (g) and volume to milliliters (mL) before dividing to find density.

Define exact numbers in measurements.

Exact numbers are counted quantities (e.g., 10 hats) or defined relationships within the same unit of measurement (e.g., 1 ft = 12 in).

What are measured numbers?

Measured numbers are obtained by using a tool to measure (e.g., 2.5 m on a ruler).

Describe how estimating a digit affects significant figures in measurements.

Estimating a digit while using a measuring tool increases the number of significant figures in the measured number.

Define significant figures in the context of measurements.

Significant figures are the digits in a number that contribute to its precision, including all non-zero digits, zeros between non-zero digits, and trailing zeros in a decimal.

Explain the significance of non-zero digits in significant figures.

Non-zero digits are always significant, meaning they count towards the total number of significant figures in a measurement.

How do zeros in the middle of a number affect significant figures?

Zeros in the middle of a number are significant and count towards the total number of significant figures.

Identify the significance of trailing zeros in a decimal number.

Trailing zeros in a decimal number are significant and contribute to the total number of significant figures.

Discuss the significance of leading zeros in a measurement.

Leading zeros at the beginning of a number are not significant and do not count towards the total number of significant figures.

What is the rule for zeros at the end of a non-decimal number regarding significant figures?

Zeros at the end of a non-decimal number are not significant and do not count towards the total number of significant figures.

Explain how to determine significant figures in multiplication and division calculations.

In multiplication and division, the answer should have the same number of significant figures as the number in the problem with the fewest significant figures.

Describe how to determine significant figures in addition and subtraction calculations.

In addition and subtraction, the answer should have the same number of decimal places as the number in the problem with the fewest decimal places.

How should intermediate answers be treated in mixed calculations involving both addition and multiplication?

Use the intermediate answers for each step to determine the final digits to keep in the answer.

Define accuracy in the context of measurements.

Accuracy refers to the closeness of a measured value to the actual or true value.

Define precision in the context of measurements.

Precision refers to the closeness of repeated measurements to each other.

Explain how the precision of a measuring tool is determined.

The precision of a measuring tool is based on the number of significant figures it provides, including the estimated digit.

What are equalities in measurement?

Equalities are relationships between equal quantities in different units of measurement, such as 1 L = 1000 mL.

Define conversion factors in relation to equalities.

Conversion factors are the fractional representations of equalities, allowing for the conversion between different units.

How is dimensional analysis used in unit conversion?

Dimensional analysis uses equalities between different units to convert a quantity from one unit to another.

What should you determine before solving a unit conversion problem?

Determine what you 'know' and what you 'need,' then gather all the equalities necessary for the plan.

Describe the setup for conversion factors in dimensional analysis.

Set up the conversion factors such that the initial unit is on the bottom of the first conversion factor to cancel out, continuing this process until the final unit is obtained.

What is the rule for converting units raised to a power?

When converting units raised to a power, both the number and the unit must be raised to that power.

How can density be used in conversions?

Density can be used as a conversion factor to convert between mass and volume.

Explain how to convert between different temperature units.

To convert between temperature units such as °F, °C, and K, specific formulas are used, such as Tc = (TF - 32) / 1.

Describe Dalton's Atomic Theory.

Dalton's Atomic Theory states that elements are composed of atoms, each element consists of only one type of atom, atoms of one element differ from those of another, atoms combine in whole number ratios to form compounds, and atoms cannot change into atoms of another element in a chemical reaction.

Explain the Law of Definite Proportions.

The Law of Definite Proportions states that all samples of a given compound have the same proportion of the constituent elements.

Define the Law of Multiple Proportions.

The Law of Multiple Proportions states that when different elements can form different compounds, they do so with different ratios of the constituent atoms.

Summarize Thomson's cathode ray tube experiment.

Thomson's cathode ray tube experiment determined that electrons are negatively charged subatomic particles that are approximately one thousand times smaller than an atom.

What did Millikan's oil drop experiment determine?

Millikan's oil drop experiment determined the charge and mass of an electron.

Describe Rutherford's gold foil experiment.

Rutherford's gold foil experiment determined the nuclear structure of an atom and confirmed the presence of protons.

Explain Soddy's contribution to atomic theory.

Soddy determined that atoms of the same element could have different masses, leading to the concept of isotopes.

What did Chadwick discover about atomic structure?

Chadwick discovered the presence of neutrons, which are neutral particles that contribute to the different mass of isotopes.

Define atomic mass unit (amu).

An atomic mass unit (amu) is defined as 1/12 of the mass of a carbon atom, equivalent to 1.6605 x 10^-24 grams.

Identify the three subatomic particles of an atom.

The three subatomic particles of an atom are protons, neutrons, and electrons.

Explain the significance of atomic number (Z).

The atomic number (Z) defines an element by the number of protons it contains.

What is the mass number (A)?

The mass number (A) is the total number of protons and neutrons in an atom.

Describe the relationship between protons and electrons in a neutral atom.

In a neutral atom, the number of protons equals the number of electrons.

Define ions and their formation.

Ions are charged atoms that result from the gain or loss of electrons.

Explain how representative elements achieve an octet of valence electrons.

Representative elements (1A-8A) gain or lose electrons to achieve a stable configuration of 8 valence electrons.

Differentiate between cations and anions.

Metals lose electrons to become positive ions called cations, while nonmetals gain electrons to become negative ions called anions.

What is the atomic charge formula?

The atomic charge is calculated as the number of protons minus the number of electrons.

Identify the components of an ion's atomic structure.

To identify the number of protons, neutrons, and electrons in an ion, one must consider its atomic number and charge.

List the first 36 elements' symbols and names.

The symbols and names of the first 36 elements must be memorized, ensuring the first letter is uppercase and the second letter is lowercase.

Define isotopes.

Isotopes are atoms of the same element that have different mass numbers due to varying numbers of neutrons.

Explain how to use atomic symbols for isotopes.

Atomic symbols provide the mass number and atomic number of a specific isotope, allowing identification of protons, neutrons, and electrons.

Describe how to calculate atomic mass.

Atomic mass is the weighted average of the mass numbers of all naturally occurring isotopes, calculated using the formula: Average mass = ∑ (fractional abundance x isotope mass).

What is mass spectrometry used for?

Mass spectrometry (MS) is used to determine the natural abundance of isotopes.

Define a mole in chemistry.

A mole is an amount of substance that contains a specific number of atoms of an element or molecules of a compound.

What is Avogadro's number?

Avogadro's number is 6.022 x 10^23, representing the number of atoms or molecules in one mole of a substance.

Describe Avogadro's number and its significance in chemistry.

Avogadro's number, 6.022 x 10^23, is the number of atoms or molecules in one mole of a substance, allowing for the conversion between the number of particles and moles.

Explain how to use molar mass in conversions.

Molar mass, expressed in grams per mole, is used to convert between the mass of a substance and the number of moles by using the formula: mass (g) = moles x molar mass (g/mol).

Define molar mass and its importance in chemistry.

Molar mass is the mass of one mole of an element or compound, typically expressed in grams per mole, and is crucial for stoichiometric calculations in chemical reactions.

How do you calculate the formula mass of a compound?

The formula mass of a compound is calculated by summing the molar masses of all the elements in the compound's formula, multiplied by their respective quantities.

Do you know the molar mass of sodium (Na)?

The molar mass of sodium (Na) is 22.99 g/mol.

Explain the relationship between moles and molecules using Avogadro's number.

One mole of any substance contains 6.022 x 10^23 molecules or atoms, allowing for conversions between moles and the number of particles.

Describe the conversion between mass and moles using molar mass.

To convert mass to moles, divide the mass of the substance by its molar mass; to convert moles to mass, multiply the number of moles by the molar mass.

List the English to metric conversion for inches to centimeters.

1 inch is equal to 2.54 centimeters.

What is the conversion factor from miles to feet?

1 mile is equal to 5280 feet.

How many liters are in a gallon?

1 gallon is equal to 3.78541 liters.

Define the relationship between kilograms and pounds.

1 kilogram is equal to 2.2046 pounds.

Explain the significance of significant figures in molar mass.

Molar mass should always be reported with four significant figures to ensure precision in calculations.

Describe the conversion from quarts to milliliters.

1 quart is equal to 946.34 milliliters.

What is the formula for calculating the mass of magnesium chloride (MgCl2) in grams?

The mass of 1 mole of MgCl2 is calculated as 24.31 g (Mg) + 2(35.45 g (Cl)) = 95.21 g.

How do you convert yards to meters?

1 yard is equal to 0.9144 meters.

Explain the conversion from pounds to ounces.

1 pound is equal to 16 ounces.

Describe the conversion from kilometers to miles.

1 kilometer is equal to 0.62137 miles.