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Chemistry What You Should Already Know Matter • Matter is defined as anything that has mass and volume. • Matter can be divided into two main groups: mixture and pure substance. • ALL matter is made of atoms. Mixtures Mixture • Two or more types of pure substances • NOT chemically combined • No definite ratio • Can be heterogeneous or homogeneous • Substances retain their original chemical and physical properties • Separated using physical properties Separation Techniques • Sort by size, shape, or color • Remove portions with magnets • Fractional distillation • Evaporation • Decant • Chromatography • Filtration • precipitation Pure Substances Elements • About 110 known at this point • Organized on the Periodic Table • Made of atoms • Each type of element has a unique atomic structure • Basic structure includes p+, n, and e- Compounds • CHEMICAL combinations of two or more elements • Combined in definite, whole # ratios • Made or separated only through chemical reactions • Simply classified as ionic or covalent • Have completely different properties than the elements that make them Basic Atomic Structure • Atoms are made of protons, neutrons, and electrons. • An ION is an atom that has lost or gained electrons. Ions can be positive or negatively charged. • An ISOTOPE is an atom with a different number of neutrons than most other atoms of that type. Subatomic Particles Proton Neutron Electron • Found in nucleus • Positive charge (+1) • Mass = 1amu • # in nucleus identifies atomic # • Found in nucleus • Neutral charge • Mass = 1amu • Number in nucleus can change without atom type changing • Found in energy levels around the nucleus • Negative charge (-1) • Mass = 0amu • Outer shell #ecan change to make ions Different Types of Atoms • Atoms are all made of subatomic particles but there are several different types of atoms • The number of subatomic particles in each atom will determine the type of atom • The # OF PROTONS will be unique for each type of atom. This is the atomic number. • The periodic table of elements is the best tool for chemistry. You should ALWAYS have one ready to use. Basic Periodic Table Information • Nearly every periodic table will have the same basic information. Usually this includes symbol, name, atomic number, and average atomic mass. Using the Periodic Table • You should already know how to use the periodic table to identify basic information related to atoms. • Number of p+ is the atomic number • Number of e- is the same as the atomic number for neutral atoms • Number of neutrons = mass number – atomic number