CHEM 161: Chapters 1-3 Review - Elements, Measurement, and Ionic Compounds

Vocabulary practice flashcards covering core topics in general chemistry including atomic structure, classification of matter, significant figures, ionic bonding, and nomenclature.

Electron

A subatomic particle carrying a negative electrical charge that orbits outside the atomic nucleus.

Atomic Nucleus

The central region of an atom where protons and neutrons are located.

Mass Number

The total sum of protons and neutrons in an atom ($\text{mass number} = \text{protons} + \text{neutrons}$).

Isotopes

Two or more atoms of the same element that have the same number of protons but different numbers of neutrons.

Element Identity

The chemical identity of an atom, which is uniquely determined by its number of protons.

Average Atomic Mass

The mass listed on the periodic table for an element, calculated as a weighted average based on natural isotope abundance.

Periods (Periodic Table)

The horizontal rows on the modern periodic table, consisting of $7$ total periods.

Groups (Periodic Table)

The vertical columns on the periodic table containing elements that share similar chemical properties because they have the same number of valence electrons.

2p Subshell

An atomic subshell that can hold a maximum capacity of $6$ electrons.

Electron Configuration of Fluorine

The ground-state arrangement of electrons for fluorine ($F$, $Z = 9$), represented as $1s^2 2s^2 2p^5$.

Dalton's Atomic Theory

A fundamental chemical theory stating, in part, that atoms of different elements combine in simple whole-number ratios to form compounds.

Element (Classification of Matter)

A pure substance that consists of only one type of atom and cannot be broken down chemically, such as copper wire ($Cu$).

Compound (Classification of Matter)

A pure substance formed by two or more elements that are chemically bonded together, such as distilled water ($H_2O$) or table sugar ($C_{12}H_{22}O_{11}$).

Homogeneous Mixture

A mixture that is uniform in appearance and composition throughout, such as normal saline ($0.9\%$ $NaCl$ in water), air, or brass.

Heterogeneous Mixture

A mixture containing physically distinct parts with non-uniform composition, such as orange juice with pulp or vegetable soup.

Brass

A homogeneous mixture (an alloy) composed of copper and zinc whose components can be separated by physical or metallurgical means rather than chemical reactions.

Scientific Method

A process of scientific inquiry involving observation, hypothesis formulation, controlled experimentation, and hypothesis revision based on evidence.

Qualitative Observation

A descriptive, non-numerical observation, such as noting that a wound appears red and inflamed or that a medication has a bitter taste.

Quantitative Observation

An observation expressed using a specific numerical value and unit, such as a body temperature of $101.4\,^\circ\text{F}$ or a volume of $5.0\,\text{mL}$.

Exact Numbers

Quantities obtained by direct counting (e.g., $100\,\text{students}$, $3\,\text{tablets}$) or defined conversions (e.g., $1000\,\text{mg} = 1\,\text{g}$), having an infinite number of significant figures.

Measured Numbers

Quantities obtained using a measuring device (e.g., $500\,\text{mg}$ dose, $24.31\,\text{g}$ sample mass), which inherently contain uncertainty and dictate significant figure limits.

Significant Figures in Addition and Subtraction

The calculation rule where the final answer is rounded to match the measurement with the fewest decimal places (e.g., $12.11\,\text{g} + 18.0\,\text{g} + 1.013\,\text{g} = 31.1\,\text{g}$).

Significant Figures in Multiplication and Division

The calculation rule where the final answer is rounded to match the value with the fewest total significant figures (e.g., $4.56\,\text{g} \div 1.4\,\text{mL} = 3.3\,\text{g}\,\text{mL}^{-1}$).

Octet Rule

The principle stating that atoms lose or gain valence electrons to achieve a full outer shell of $8$ electrons ($2$ for $H$, $He$, and $Li$), matching the stable electron configuration of a noble gas.

Cation

A positively charged ion formed when a metal atom loses one or more of its valence electrons.

Anion

A negatively charged ion formed when a nonmetal atom gains electrons to achieve a complete valence octet.

Type II Ionic Naming System

A nomenclature system used for metals with variable charge (like iron or copper) that specifies the ionic charge using a Roman numeral in parentheses, such as iron(II) for $Fe^{2+}$ in $FeCl_2$.

Polyatomic Ions

Tightly bound groups of covalently bonded atoms that carry an overall net charge, such as ammonium ($NH_4^+$), hydroxide ($OH^-$), carbonate ($CO_3^{2-}$), phosphate ($PO_4^{3-}$), and nitrate ($NO_3^-$).

Oxyanion Naming Pattern

A naming rule based on relative oxygen content using systematic prefixes and suffixes: per-…-ate ($BrO_4^-$ perbromate), -ate ($BrO_3^-$ bromate), -ite ($BrO_2^-$ bromite), and hypo-…-ite ($BrO^-$ hypobromite).

Formula Mass

The sum of the atomic masses of all atoms present in a chemical formula unit, such as $58.44\,\text{g}\,\text{mol}^{-1}$ for $NaCl$ and $74.10\,\text{g}\,\text{mol}^{-1}$ for $Ca(OH)_2$.

Ionic Compound Melting Point

The high melting temperature characteristic of ionic solids due to the high thermal energy required to overcome strong electrostatic attractions throughout the entire crystal lattice.

Ionic Electrical Conductivity

The ability of ionic compounds to conduct electric current when molten or dissolved in water, during which free-moving ions carry charge, contrasting with non-conducting solid forms where ions are locked in place.

Dissociation Equation of Normal Saline

The process $NaCl_{(s)} \rightarrow Na^+_{(aq)} + Cl^-_{(aq)}$ in aqueous solution, which yields free electrolytes needed immediately by the body for nerve and muscle function and fluid balance.