Class notes for Chapter 1: Atoms in the class General Chemistry: Macroscopic Investigations and Reaction Principles (CHEM 130). Subjects covered include classifying matter and elements, the scientific approach to chemistry, subatomic particles, atomic structure, the cathode ray and oil drop experim...
●The properties of matter are determined by the structure of the atoms and molecules that compose it
●Atoms/molecules determine how matter behaves
●Matter: anything that occupies space and has mass
○Particulate: composed of particles
○Particle structure determines the properties of matter
●Atoms: submicroscopic particle that constitutes the fundamental building block of ordinary matter; the smallest identifiable unit of an element
○91 different types
○Smallest particle of an element that is identifiable as that element ●Molecules: two or more atoms joined chemically in a specific geometric arrangement
○Very small physically
●Structure is very important! ○Ex: Graphite and diamond are exactly the same thing, but the STRUCTURE makes graphite easy to break away and diamond to be strong
●Chemistry: science that seeks to understand the properties of matter by studying the structure of the particles that compose it
Classifying Matter: A Particulate View
●Substance: a specific instance of matter (ex: air, water, sand, etc)
●State of matter: classification of a form of matter as a solid, liquid, or gas
○Depends on relative positions of particles and how strongly they interact with one
another
●Composition of matter: type of particles that compose matter
States of Matter
●Solid: atoms or molecules are packed close to one another in fixed locations with definite volume
●Liquid: atoms or molecules pack about as closely as they do in solid matter but are free to move relative to each other → fixed volume but not fixed shape
●Gas: atoms or molecules have a great deal of space between them and are free to move relative to each other → lacks definite shape or volume
○Compressible
Elements, Compounds, and Mixtures
●Composition
○First division
■Pure substance: only one type of particle (one component)
●Composition is invariant: does not vary from one sample to another
●Can be individual or grouped atoms ●Ex: Water, helium, table salt
●Can be one of two things:
○Element: substance that cannot be chemically broken down into simpler substances
○Compound: substance that is composed of two or more elements in fixed proportions
■More common than elements
■Mixture: composed of two or more particles in proportions that can vary from one sample to another
●Ex: Sweet tea
●Can be one of two things:
○Heterogeneous: mixture in which the composition varies from one region to another
■Do NOT mix uniformly
○Homogeneous: mixture in which the composition is uniform throughout
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