Chapter One: Introduction to Chemistry and Atomic Structure

Chemistry

Science studying matter's behavior and properties.

Matter

Anything with mass and occupies space.

States of Matter

Solid, liquid, gas based on physical state.

Solid

Definite shape and volume.

Liquid

Definite volume, shape of container.

Gas

No definite shape or volume; expands.

Pure Substance

Fixed composition, made of one component.

Mixture

Combination of two or more pure substances.

Homogeneous Mixture

Uniform appearance and composition throughout.

Heterogeneous Mixture

Distinct regions with different compositions.

Element

Cannot be chemically broken into simpler substances.

Compound

Contains two or more elements in a definite ratio.

Intensive Property

Independent of the amount of substance present.

Extensive Property

Varies with the amount of substance present.

Physical Property

Observable characteristics without changing composition.

Chemical Property

Describes behavior during composition change.

Physical Change

No change in composition; only physical state changes.

Chemical Change

Composition of matter changes; new substances formed.

Separation of Mixtures

Using physical methods based on component properties.

Filtration

Separation technique using a barrier to separate solids.

Distillation

Separation based on differences in boiling points.

Chromatography

Technique for separating components based on movement.

Odor of paint thinner

Characteristic smell from volatile organic compounds.

Ozone decomposition

Breakdown of ozone by ultraviolet light exposure.

Silver shine

Luster from polished silver surface.

Iron rust tendency

Iron's susceptibility to oxidation and corrosion.

Boiling point of ethyl alcohol

Temperature at which ethyl alcohol vaporizes, 78.37°C.

Flammability of ethyl alcohol

Ability of ethyl alcohol to ignite and burn.

Physical change

Change affecting form, not chemical composition.

Chemical change

Change resulting in new chemical substances.

Scientific method

Systematic approach for scientific investigation.

Observations

Data describing nature's characteristics or behaviors.

Hypothesis

Tentative explanation based on observations.

Scientific law

Statement summarizing observed phenomena consistently.

Theory

Explanation of phenomena based on experimental validation.

Law of conservation of mass

Matter is neither created nor destroyed in reactions.

Law of definite proportions

Compounds have consistent elemental composition ratios.

Law of multiple proportions

Different compounds from same elements have simple ratios.

Atomos

Term for indivisible particles proposed by ancient philosophers.

Dalton's atomic theory

Theory stating matter consists of indivisible atoms.

Chlorine reactivity

Observation noting chlorine's high reactivity as a gas.

Matter composition

All matter consists of particles called atoms.

Chemical reaction matter conservation

Total mass remains constant during chemical reactions.

Law of Definite Proportions

Mass ratio of elements in a compound is constant.

Decomposition of Water

18.0 g of water yields 16.0 g O2 and 2.0 g H2.

Oxygen-to-Hydrogen Ratio

Mass ratio of oxygen to hydrogen is 8:1.

Law of Multiple Proportions

Mass ratios of elements in compounds are whole numbers.

John Dalton

Published the law of multiple proportions in 1804.

Carbon Compounds Example

Carbon monoxide and dioxide illustrate multiple proportions.

Dalton's Atomic Theory

Atoms are indivisible and combine in fixed ratios.

Atomic Indivisibility Question

Are atoms composed of smaller particles?

Cathode Rays

Particles traveling from cathode to anode in experiments.

Properties of Cathode Rays

Travel in straight lines and carry negative charge.

Thomson's Charge-to-Mass Ratio

e/m = -1.76 × 10^8 Coulomb/g.

Millikan's Oil Drop Experiment

Measured electron charge and determined its mass.

Electron Charge

Charge of electron is -1.60 × 10^-19 C.

Mass of Electron

Mass of electron is 9.10 × 10^-28 g.

Thomson's Plum-Pudding Model

Electrons embedded in a positively charged sphere.

Radioactivity

Spontaneous emission of radiation discovered by Becquerel.

Types of Radiation

Alpha, beta, and gamma rays are radiation types.

Alpha Rays

Positively charged helium nuclei emitted during radioactivity.

Beta Rays

Negatively charged electrons emitted during radioactivity.

Gamma Rays

Neutral high-energy radiation emitted during radioactivity.

Rutherford's Gold Foil Experiment

Demonstrated nuclear structure of the atom.

Nuclear Model of Atom

Atom's mass and positive charge concentrated in nucleus.

Electron

Negatively charged particle outside the nucleus.

Proton

Positively charged particle in the nucleus.

Neutron

Neutral particle within the nucleus.

Atomic Number (Z)

Number of protons in an atom's nucleus.

Mass Number (A)

Total of protons and neutrons in an atom.

Isotope

Atoms with same protons, different neutrons.

Natural Abundance

Percentage of each isotope in a sample.

Cation

Positively charged ion from losing electrons.

Anion

Negatively charged ion from gaining electrons.

Atomic Mass

Average mass of an element's isotopes.

Mass Spectrometry

Technique for measuring atomic masses and isotopes.

Mole

SI unit for amount of substance, 6.022 x 10^23.

Molar Mass

Mass of one mole of atoms in grams.

Atomic Symbol

One or two letters representing an element.

Berzelius

Inventor of symbols for chemical elements.

Subatomic Particles

Particles smaller than atoms: protons, neutrons, electrons.

Element

Substance defined by its unique number of protons.

Neutral Atom

Atom with equal numbers of protons and electrons.

Relative Atomic Mass

Weighted average of isotopes' masses in a sample.

Chemical Notation

Symbol followed by mass number for isotopes.

Avogadro's Number

6.022 x 10^23, number of entities in a mole.

Rutherford's Model

Early atomic model emphasizing nucleus and electrons.