General Chemistry Fundamentals

Vocabulary flashcards covering measurement principles, atomic structure, periodic table trends, dimensional analysis, and mass spectrometry based on the lecture notes.

Accuracy

How close a measured value is to the accepted or true value.

Precision

How closely repeated measurements agree with one another; precision does not guarantee accuracy.

Exact number

A counted or defined value with unlimited significant figures that does not limit rounding.

Captive zeros

Zeros located between nonzero digits that are always significant, as in $1002$ ($4$ significant figures).

Leading zeros

Zeros that only locate the decimal point and are not significant, as in $0.0045$ ($2$ significant figures).

Trailing zeros

Zeros at the end of a number that are significant when a decimal point makes the precision clear, as in $2.300$ ($4$ significant figures).

Scientific notation

A method of writing a number as a coefficient from $1$ up to $10$ multiplied by a power of ten.

Dimensional analysis

A conversion method that multiplies by conversion factors arranged so unwanted units cancel.

Conversion factor

A ratio of equivalent quantities equal to $1$, such as $\frac{100\,\text{cm}}{1\,\text{m}}$.

Density

Mass per unit volume, represented by the formula $d = \frac{m}{V}$.

Percent by mass

The percentage of a component's mass in a solution, calculated as $\text{percent by mass} = \left(\frac{\text{mass of component}}{\text{mass of solution}}\right) \times 100\%$.

Matter

Anything that has mass and occupies space.

Pure substance

Matter with a fixed composition, which is either an element or a compound.

Element

A pure substance made of one type of atom that cannot be chemically broken into simpler substances.

Compound

A pure substance formed by two or more elements chemically combined in a fixed ratio.

Mixture

A combination of two or more substances physically combined in variable proportions.

Homogeneous mixture

A mixture with uniform composition throughout; also called a solution.

Heterogeneous mixture

A mixture with nonuniform composition or visibly different regions.

Proton

A subatomic particle located in the nucleus with a charge of $+1$ and an approximate mass of $1\,\text{amu}$.

Neutron

A subatomic particle located in the nucleus with a charge of $0$ and an approximate mass of $1\,\text{amu}$.

Electron

A subatomic particle located outside the nucleus with a charge of $-1$ and negligible mass compared with a proton.

Atomic number ($Z$)

The number of protons in the nucleus of an atom, which identifies the element.

Mass number ($A$)

The total number of protons and neutrons in one isotope, expressed as $A = p + n$.

Isotope

Atoms of the same element with the same number of protons but different numbers of neutrons.

Ion

An atom or group of atoms with a net charge resulting from gaining or losing electrons.

Cation

A positively charged ion formed by losing electrons.

Anion

A negatively charged ion formed by gaining electrons.

Complete isotope notation

Notation written with mass number at upper left, atomic number at lower left, element symbol in center, and charge at upper right: $^{A}_{Z}\text{X}^{\text{charge}}$.

Mass spectrometry

A method that separates ions according to their mass-to-charge ratio ($m/z$) and measures their relative abundance.

Mass-to-charge ratio ($m/z$)

The ratio obtained by dividing an ion's mass by the magnitude of its charge.

Average atomic mass

The weighted average mass of naturally occurring isotopes, given by $\text{average atomic mass} = \Sigma(\text{isotope mass} \times \text{decimal abundance})$.

SI base unit for length

Meter ($\text{m}$).

SI base unit for mass

Kilogram ($\text{kg}$).

SI base unit for time

Second ($\text{s}$).

SI base unit for temperature

Kelvin ($\text{K}$).

SI base unit for amount of substance

Mole ($\text{mol}$).

Defined equivalency

A relationship fixed by definition that is exact and does not limit significant figures, such as $1\,\text{in} = 2.54\,\text{cm}$.

Measured equivalency

A relationship determined by measurement whose stated precision can limit significant figures.

Period

A horizontal row of the periodic table in which atomic number increases from left to right.

Group or family

A vertical column of the periodic table containing main-group elements with similar valence-electron patterns and chemical properties.

Alkali metals

Group 1 metals (excluding hydrogen) that are reactive and usually form $+1$ ions.

Alkaline-earth metals

Group 2 metals that commonly form $+2$ ions.

Halogens

Group 17 reactive nonmetals that commonly form $-1$ ions.

Noble gases

Group 18 elements with filled valence shells that are generally unreactive and form no monatomic ions.

Metals

Elements on the left and center of the periodic table that are lustrous, malleable, ductile, good conductors of heat and electricity, and tend to lose electrons.

Nonmetals

Elements primarily on the upper right of the periodic table (plus hydrogen) that are often dull, brittle when solid, poor conductors, and tend to gain or share electrons.

Metalloids

Elements along the staircase boundary between metals and nonmetals with intermediate properties; many are semiconductors.

General atomic-radius trend

Atomic radius generally increases down a group and decreases from left to right across a period.

General ionization-energy trend

Ionization energy generally decreases down a group and increases from left to right across a period.

General electronegativity trend

Electronegativity generally decreases down a group and increases toward the upper right of the periodic table (excluding noble gases).

General metallic-character trend

Metallic character generally increases down and to the left on the periodic table.