Test 1 Study Guide: Chapters 1-2 – Matter on the Atomic Scale; Elements and Compounds

A comprehensive set of vocabulary flashcards covering key terms from Chapters 1-2: matter on the atomic scale and elements & compounds.

macroscopic scale

Observation and measurement at the level visible to the naked eye.

microscopic scale

Observation and measurement at a scale visible only with magnification (e.g., atoms, molecules).

atomic scale

Observation and measurement at the level of atoms and subatomic particles.

element

Substance made of only one kind of atom.

atom

The basic unit of an element; the smallest unit retaining the element’s identity.

chemical compound

Pure substance composed of two or more elements chemically bonded in a fixed ratio.

molecule

Two or more atoms bonded together; the smallest unit of a compound that retains its properties.

pure substance

Substance with a fixed composition and definite properties (elements or compounds).

mixture

Combination of two or more substances that are not chemically bound.

homogeneous mixture

Uniform composition throughout; components not visibly different.

heterogeneous mixture

Nonuniform composition; components are distinguishable.

physical property

Characteristic observed without changing the substance’s composition (e.g., color, density).

chemical property

A substance’s ability to undergo a chemical change.

physical change

Change in appearance or state without changing composition.

chemical change

Transformation that produces one or more new substances.

solid

State with definite shape and volume; particles vibrate in place.

liquid

State with definite volume but takes shape of container.

gas

State with no definite shape or volume; expands to fill space.

fusion (melting)

Solid to liquid phase change.

vaporization

Liquid to gas phase change (boiling or evaporation).

sublimation

Solid to gas phase change without passing through liquid.

freezing

Liquid to solid phase change.

condensation

Gas to liquid phase change.

deposition

Gas to solid phase change.

melting point

Temperature at which a solid becomes a liquid.

boiling point

Temperature at which a liquid boils (vapor pressure equals external pressure).

seven SI base units

Meter (m), kilogram (kg), second (s), ampere (A), kelvin (K), mole (mol), candela (cd).

volume (derived unit)

SI derived unit for volume: cubic meter (m^3); commonly liters (L) in practice.

density (derived unit)

Mass per unit volume; unit is kg/m^3.

energy (derived unit)

Ability to do work; unit is the joule (J).

absolute zero

Lowest possible temperature: 0 K, −273.15 °C, −459.67 °F.

temperature scale conversions

Convert temperatures between Kelvin, Celsius, and Fahrenheit.

dimensional analysis

Using conversion factors to convert between units.

atomic number

Number of protons in the nucleus; defines the element.

mass number

Total number of protons and neutrons in the nucleus.

isotope

Atoms of the same element with different mass numbers (different neutrons).

atomic weight

Weighted average of an element’s isotopic masses based on abundance.

ion

Charged particle formed by loss or gain of electrons.

cation

Positively charged ion.

anion

Negatively charged ion.

ionic compound

Compound composed of cations and anions held together by ionic bonds.

covalent compound

Compound formed by sharing electrons between nonmetals.

binary nonmetal covalent naming

Systematic naming of compounds formed from two nonmetals using prefixes.

inorganic acid

Acidic compound containing hydrogen; in solution, donates H+. Systematic naming follows rules (e.g., HCl = hydrochloric acid).

oxoacids

Acids containing hydrogen, oxygen, and another element; named using -ic/-ous endings.

allotrope

Different structural forms of the same element in the same phase (e.g., carbon: diamond, graphite).

periods and groups

Periods are horizontal rows; groups are vertical columns in the periodic table.

alkali metals

Group 1 metals; highly reactive, especially with water.

alkaline earth metals

Group 2 metals; reactive, but less so than alkali metals.

pnictogens

Group 15 elements (nitrogen family).

chalcogens

Group 16 elements (oxygen family).

halogens

Group 17 elements; highly reactive nonmetals.

noble gases

Group 18 elements; very low reactivity; noble/inert gases.

main-group elements

Elements in s- and p-blocks of the periodic table.

transition metals

Elements in the d-block; variable oxidation states and complex chemistry.

lanthanides

f-block elements 4f; often called rare earth metals.

actinides

f-block elements 5f; radioactive elements.

metals

Elements with metallic bonding; typically good conductors of heat and electricity.

nonmetals

Elements with poor metallic properties; often gases or brittle solids.

metalloids

Elements with properties between metals and nonmetals.