八年级科学期末考试复习指导（Eighth grade science final exam revision guide）.doc

八年级科学期末考试复习指导（Eighth grade science final exam revision guide） The first chapter 1 1 model The four most important scientific models of the 20th century: 1. Quark model 2. The big bang model 3. Earth plate model 4. DNA double helix model 2. Molecules, atoms (1) the molecule is the smallest particle that keeps the chemical properties of matter. Some substances are made up of molecules, but some are made of atoms (e.g., graphite, common metals, etc.) (2) the number of molecules is determined by the type and number of atoms. (3) the atoms that make up the molecules can be the same atoms or different kinds of atoms. (4) when the same atoms form different substances, the structure is different. (5) the smallest particles of atomic chemical change. (6) the atomic structure is in the atom: the number of nuclear charges = the number of protons = the number of electrons (7) the same class of atomic elements as nuclear power. (8) the original neutron number has the same nuclear charge number and the same atomic number. (9) ions: electrically charged atoms or groups of atoms. A positively charged cation, a negatively charged anion. The ion charge is equal to the valence, which is essentially formed by the electron gain and loss of the original son. (10) nuclear power nuclear number 4 (11) nuclear power nuclear number 4 easy to lose electrons Elements of 3. The elements in the earths crust range from large to small in order: oxygen - silicon aluminium - calcium, potassium, magnesium, potassium, magnesium, and memory: the beauty of a daughter 4. Differences and links between subatomic and atomic: Concept of molecules and atoms to keep physical chemical properties of a particle chemical changes in the minimum difference between particle properties In a chemical change can be divided into, maintain physical chemical properties In a chemical change not constitute by the child component Composed of protons, neutrons, electrons in common with certain quality and size, have a certain