CHAPTER 1 SUMMARY PDF

# CHAPTER SUMMARY ## 1.1. Atomic Theory - At the heart of chemistry is the concept of atoms, the small blocks from which all matter is built. - Dalton's Atomic Theory provided the first pieces of systematic evidence that matter was composed of atoms. ## 1.2. Atomic Building Blocks - Atoms are comp...

# CHAPTER SUMMARY ## 1.1. Atomic Theory - At the heart of chemistry is the concept of atoms, the small blocks from which all matter is built. - Dalton's Atomic Theory provided the first pieces of systematic evidence that matter was composed of atoms. ## 1.2. Atomic Building Blocks - Atoms are comprised of protons (positive charge), electrons (negative charge), and neutrons (no charge). - The nucleus of the atom contains most of the mass in an atom and is comprised of the protons and neutrons. - Electrons exist outside of the nucleus. ## 1.3. Elements and Nuclides - A chemical element is uniquely identified by its atomic number; all atoms of an element contain the same number of protons. - Nuclides of an element that differ in the number of neutrons are called isotopes. - Each nuclide is associated with a specific atomic number and mass number and can be given a symbol and name based on those numbers. ## 1.4. Substances and Mixtures - A sample of matter can be classified as one of four different types. - Pure substances—elements and compounds—contain the same ratio and arrangement of atoms throughout, with one type of atom for elements and more than one for compounds. - Mixtures of different pure substances can be homogeneous, with the same appearance throughout, or heterogeneous, with visible differences in composition. ## 1.5. Physical and Chemical Properties - Any substance can be described by a number of physical and chemical properties that can be observed or measured. - Physical properties can be observed without changing the identity of a substance; chemical properties cannot. - Matter exists in different physical phases (solid, liquid, gas). ## 1.6. Energy - Energy, the ability to do work, comes in multiple different forms that can be converted from one type to another but never destroyed. - Chemical energy and thermal energy are of particular interest; the former is energy stored in atomic configurations, and the latter is associated with random motion. - If energy is released by some process, that process is exergonic (and exothermic if heat is released); if energy must be added for the process to take place, the process is endergonic (and endothermic if heat is absorbed).