6.6 – NOTES Symbols, Formulas, and Equations

B.4 Particulate View of Water Particulate level: the level of atoms and molecules Atoms Building blocks of matter Made up of protons and neutrons in the nucleus, and electrons in the electron cloud Elements One single type of atom – gold (Au), Oxygen (O) Compound Two or more elements bonded together Written using formulas – H2O, CuSO4

Elements and compounds are considered to be substances Substances have uniform and fixed composition and properties separate from the elements themselves   Smallest unit of a substance is a molecule Molecules are held together by bonds, which are either covalent or ionic

B.6 Symbols, Formulas, and Equations Chemists use an international language to convey information so everyone can understand it The language of chemistry is made of symbols, formulas, and equations   Chemical symbols- letters Each element has a unique symbol of 1 or 2 letters; some based on old Latin name and not related to what they are known by today 1st letter – capital 2nd letter – lower case Lead Pb plumbum Tin Sn Stannum Potassium K Katrium Sodium Na Natrium

Chemical formulas- words Make use of subscripts Number written below line H2O Tell how many atoms of each kind are present in 1 unit of the substance   Counting atoms in a formula How many atoms of each element are present in the following compounds? Al2(SO4)3 FeCl3 Al – 2 Fe – 1 S – 3 Cl – 3 O - 12

Chemical equations- sentences 2 H2 + O2  2H2O   Summarize details of chemical reactions Reactants- what you start with; left side of the arrow Products- what you finish with; right side of the arrow

Diatomic molecules Br2 I2 N2 Cl2 H2 O2 F2 “Brinclhof” Made up of 2 atoms of the same element Never found as single atoms in nature when the element is by itself. The diatomic elements are   Br2 I2 N2 Cl2 H2 O2 F2 “Brinclhof”

B.8 the Electrical Nature of Matter Like charges repel; opposite charges attract   Atoms are made up of three components that are charged + protons (p+)  – electron (e-) 0 (neutral) – neutrons (n0) The attraction between protons and electrons is what holds atoms together in chemical bonds Nucleus – center of atom; holds protons and neutrons – positive charge Electron cloud – region around nucleus where electrons are negative charge Atoms are neutral – # protons = # electrons