Chapter 1: Chemical Foundations

Comprehensive vocabulary flashcards covering the chemical foundations, measurements, unit conversions, significant figures, and classification of matter from Chapter 1.

Chemistry

The study that connects the macroscopic world we observe with the microscopic world of atoms and molecules; a substance’s properties depend on the arrangement and connection of its atoms.

Chemical change

A process that reorganizes atoms into substances with new composition and properties, while the atoms themselves are conserved.

Hypothesis

A tentative, testable explanation or prediction within the scientific method.

Theory/model

A broad explanation of why nature behaves as it does that can be revised when new evidence demands it.

Qualitative observations

Observations that describe the characteristics of a substance without using numbers.

Quantitative observations

Observations that include both a number and a unit.

Mass

A measure of the resistance to change in motion of an object.

Weight

The force exerted by gravity on the mass of an object.

Kelvin (K)

The SI unit for temperature, which is written without a degree sign.

High-yield SI prefixes

kilo (k) = $10^{3}$; centi (c) = $10^{-2}$; milli (m) = $10^{-3}$; micro ($\mu$) = $10^{-6}$; nano (n) = $10^{-9}$.

Volume relationships

$1\,dm^{3} = 1\,L$; $1\,cm^{3} = 1\,mL$; $1\,L = 1000\,mL = 1000\,cm^{3}$.

Precision

The degree to which repeated measurements agree closely with one another.

Accuracy

The degree to which a measured value agrees with the true or accepted value.

Random error

An error that varies high and low and can be averaged out through repeated measurements.

Systematic error

An error that consistently biases results in one direction and must be identified and corrected.

Significant figure rules for zeros

Leading zeros are never significant; zeros between nonzero digits are always significant; trailing zeros are significant only when a decimal point is shown.

Exact numbers

Counted or defined numbers, such as $1\,in = 2.54\,cm$, that do not limit the precision of calculation results.

Dimensional analysis

A process for converting units by multiplying a given value by conversion factors equal to $1$, arranged so that unwanted units cancel.

Temperature conversion formulas

$T_{K} = T_{C} + 273.15$; $T_{C} = (T_{F} - 32) \times \frac{5}{9}$; $T_{F} = (T_{C} \times \frac{9}{5}) + 32$.

Density

An identifying physical property calculated using the formula $d = \frac{mass}{volume}$, commonly expressed in $g/mL$ or $g/cm^{3}$.

Element

A pure substance that cannot be decomposed into simpler substances by physical or chemical means.

Compound

A substance with a constant composition that can be chemically decomposed into its constituent elements.

Homogeneous mixture (solution)

A mixture containing uniform and visibly indistinguishable parts, such as air or brass.

Heterogeneous mixture

A mixture containing visibly distinguishable regions or components, such as sand in water.

Physical change

A change in the form or state of matter (melting, boiling, or dissolving) where the composition does not change.

Distillation

A separation method that uses differences in volatility/boiling behavior to vaporize and سپس condense the more volatile component.

Filtration

A separation method used to remove an insoluble solid from a liquid using a barrier such as filter paper.

Chromatography

A separation technique where components of a mixture distribute differently between a stationary phase and a mobile phase and travel at different rates.