Matter and Measurement - Chapter 1: Introduction

A set of Question-and-Answer flashcards covering key concepts from Chapter 1: Introduction to Matter and Measurement.

Why study Chemistry?

Chemistry helps us understand how the world works, shows its central role in science, and informs decisions related to health, environment, energy, and technology.

What is Chemistry?

The science that studies the composition of matter, the changes it undergoes, the energy involved, the theories and laws that explain those changes, and the properties of atoms and molecules.

What is Matter?

Anything that has mass and occupies space.

How is matter classified by composition?

As pure substances (elements and compounds) or mixtures (homogeneous and heterogeneous).

What is an element?

A pure substance consisting of a single type of atom that cannot be decomposed into simpler substances by chemical means.

What is a compound?

A pure substance composed of two or more different elements chemically bonded; its molecules have a fixed composition and can be decomposed into simpler substances.

What is a mixture?

Matter with variable composition containing two or more substances that can be separated by physical methods.

What is Mass?

The quantity of matter a body possesses; measured in units of mass such as grams or kilograms.

What is the difference between mass and amount of substance (moles)?

Mass is the quantity of matter; amount of substance (moles) counts the number of particles—distinct from mass.

What is Plasma?

An ionized gas, considered a fourth state of matter, formed at high temperatures (e.g., lightning).

What are the three classical states of matter and their key traits?

Solids have fixed shape and volume; liquids have fixed volume but take the shape of their container; gases have neither fixed shape nor volume and are highly compressible and fluid.

What are crystalline solids?

Solids whose particles are arranged in an orderly, geometric pattern; examples include salts, diamonds, sugar crystals.

What are amorphous solids?

Solids with particles arranged randomly without a long-range order; examples include plastics and glass.

What are allotropes?

Different forms of the same element with different structures and properties (e.g., carbon as diamond, graphite, graphene; O2 vs O3).

What is the Scientific Method?

A systematic approach: make observations, perform experiments, find patterns, formulate hypotheses, and test them to develop theories.

How is matter classified by composition?

As heterogeneous or homogeneous mixtures, or as pure substances (elements or compounds).

What distinguishes a pure substance from a mixture?

Pure substances have fixed composition; mixtures have variable composition.

What is the difference between elements and compounds?

Elements are pure substances of a single type of atom; compounds are substances formed from two or more elements chemically combined.

What are physical changes?

Changes that alter the state or appearance of matter without changing its composition.

What are chemical changes?

Changes that alter the composition of matter, forming new substances.

List the common phase changes.

Melting (fusion), Vaporization (boiling/evaporation), Condensation, Freezing, Sublimation, Deposition.

Is boiling water a physical or chemical change?

Physical change.

Is iron rusting a physical or chemical change?

Chemical change (oxidation).

What methods separate mixtures?

Filtration, Distillation (and Extraction), and Chromatography.

What is Dimensional Analysis?

A method to convert quantities using conversion factors to obtain desired units.

What are extensive vs. intensive properties?

Extensive properties depend on amount (mass, volume); intensive properties do not (density, temperature, color, boiling point).

What is the SI base unit for length?

Meter (m).

What is the SI base unit for mass?

Kilogram (kg).

What is the SI base unit for temperature?

Kelvin (K).

What is the SI base unit for time?

Second (s).

What is the SI base unit for amount of substance?

Mole (mol).

What is the SI base unit for luminous intensity?

Candela (cd).

What is the SI unit for volume and its relation to liters?

Volume is in cubic meters (m^3); common practical units are liters (L) and milliliters (mL); 1 L = 1 dm^3; 1 mL = 1 cm^3.

What are common prefixes and their powers of ten?

Tera (T) 10^12; Giga (G) 10^9; Mega (M) 10^6; kilo (k) 10^3; deci (d) 10^-1; centi (c) 10^-2; milli (m) 10^-3; micro (μ) 10^-6; nano (n) 10^-9; pico (p) 10^-12; Angstrom (Å) 10^-10.

What is density?

Mass per unit volume (ρ = m/V); density is an intensive property; its units vary with phase; ice is less dense than liquid water.

What is pressure?

Force per unit area; an intensive property used to describe how force is distributed over an area.

What is Dimensional Analysis used for?

To convert quantities from one unit system to another using conversion factors.

What are significant figures?

Digits that carry meaning about the precision of a measurement; nonzero digits are always significant; zeros may or may not be significant depending on position and decimal point.

What are the rules for significant figures in multiplication/division?

The result should have the same number of significant figures as the measurement with the fewest significant figures.

What are the rules for significant figures in addition/subtraction?

The result should have the same number of decimal places as the measurement with the fewest decimal places.

What is accuracy vs. precision?

Accuracy is how close a measurement is to the true value; precision is how close repeated measurements are to each other.

What does uncertainty in measurements mean?

Inherent limitations due to instrument precision, experimental design, and random errors; the last digit is uncertain.

What does the three-student example illustrate about accuracy and precision?

Student A is neither accurate nor precise; Student B is precise but not accurate; Student C is both accurate and precise.