Introduction to Chemistry and Measurement Concepts

Chemistry

Science of matter and its changes.

Matter

Anything with mass and occupies space.

Atom

Smallest particle retaining chemical identity.

Molecule

Two or more atoms bonded together.

Periodic Table

Arrangement of elements by atomic number.

Solid

Fixed shape and volume, incompressible.

Liquid

Fixed volume, no fixed shape, incompressible.

Gas

No fixed shape or volume, compressible.

Physical Change

Change in state without altering chemical identity.

Melting

Solid to liquid phase transition, requires energy.

Vaporization

Liquid to gas phase transition, requires energy.

Sublimation

Solid to gas phase transition, requires energy.

Freezing

Liquid to solid phase transition, releases energy.

Condensation

Gas to liquid phase transition, releases energy.

Deposition

Gas to solid phase transition, releases energy.

Physical Properties

Observed without changing chemical identity.

Chemical Properties

Observed by changing chemical identity.

Extensive Property

Depends on amount of matter present.

Intensive Property

Independent of amount of matter present.

Substance

Matter with definite composition and distinct properties.

Element

Composed of one type of atom, cannot be broken down.

Compound

Substance formed from two or more elements chemically bonded.

Mixture

Combination of substances separable by physical means.

Heterogeneous Mixture

Composition is not uniform throughout the mixture.

Homogeneous Mixture

Uniform blend of substances throughout the mixture.

Scientific Method

Systematic approach emphasizing observation and experimentation.

Hypothesis

Tentative explanation, often in 'If-then' format.

Experiment

Controlled observation of natural phenomena for reproducibility.

Theory

Broader explanation of widely observed natural phenomena.

Law

Concise statement about fundamental relationships in nature.

Law of Conservation of Mass

Mass is neither created nor destroyed in reactions.

Chemical Reaction

Process where reactants transform into products.

Electronic Balance

Device measuring mass or quantity of substances.

Scientific Notation

Method to express very large or small numbers.

General Expression of Scientific Notation

A × 10^n, where n is an integer.

Significant Figures

Digits in a measurement indicating precision and uncertainty.

Significant Figures Rule 1

All nonzero digits are significant.

Significant Figures Rule 2

Zeroes between nonzero digits are significant.

Significant Figures Rule 3

Placeholding zeroes are not significant.

Significant Figures Rule 4

Trailing zeroes after decimal are significant.

Addition/Subtraction Rule

Round to least decimal places in results.

Significant Figures in Calculations

Rules applied to maintain precision in results.

Precision

Agreement among repeated measurements of the same quantity.

Accuracy

How close a measurement is to the true value.

SI Units

International System of Units for scientific measurements.

Derived Units

Units formed from base SI units, like density.

Dimensional Analysis

Method for converting units using conversion factors.

Conversion Factor

Exact ratio used to convert between units.

Density

Mass per unit volume, expressed as g/mL or kg/m3.

Volume of Metal

Calculated by water displacement method in a graduated cylinder.

Temperature

Quantitative measure of thermal energy in matter.

Celsius Scale

Temperature scale commonly used outside the USA.

Fahrenheit Scale

Temperature scale primarily used in the USA.

Kelvin Scale

Absolute temperature scale; 0 K is absolute zero.

Absolute Zero

Lowest possible temperature, 0 K or -273.15°C.

Multiplication Rule

Round to the least significant figures in multiplication.

Division Rule

Round to the least significant figures in division.

Mass of Sulfuric Acid

Calculated using density and volume of the liquid.

Temperature Conversion

Equations to convert between Celsius, Fahrenheit, and Kelvin.

Water Displacement

Method to measure volume by submerging an object.

Conversion from mL to cm3

1 mL equals 1 cm3, used in density calculations.

Exact Quantities

Numbers that have no uncertainty, used in conversions.