Chapter 3 - Chapter 3: Molecules, Compounds, and Chemical...

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Chapter 3: Molecules, Compounds, and Chemical Equations Elements in their Natural States Very few Elements are found in pure ‘atomic’ form in nature Some Elements consist of DIATOMIC MOLECULES in their uncombined forms - Hydrogen, Nitrogen, Oxygen, Fluorine, Chlorine, Bromine, and Iodine 3.3 Representing Compounds : Chemical Formulae and Molecular Models 3.2 Chemical Bonds (see Ch 9) 3.2/3.3 Compounds Compound – a substance made up of atoms of two or more elements, chemically combined, with the different kinds of atoms in fixed proportions - N.B. Compounds CAN be decomposed into simpler compounds or elements by chemical means! Please note – the properties of an element in its natural state are generally NOT the same as its properties in a compound 3.2/3.3 Chemical Formula A chemical formula shows the SYMBOLS and RATIO of the atoms of an element in a compound 3.2/3.3 Molecular Compounds and their Formula A Molecule is a discrete, uncharged group of two or more atoms held together in a definite spatial arrangement by forces called covalent bonds A Molecular formula shows the actual number of atoms of each element in a molecule of the compound 3.2/3.3 Empirical Formulae of Molecular Compounds The Empirical formula shows the smallest whole number ratio of each type of atom in a compound - Empirical and molecular formulae are related by an integral factor, and are sometimes equal A Structural formula shows the covalent bonds between atoms in a molecule A Condensed Structural formula also shows the connections between atoms in a molecule 3.2/3.3 ‘3-D’ Models of Molecular Compounds ‘Ball and stick’ and ‘Space filling’ models can be useful when visualizing the microscopic world 3.2/3.3 Ionic Compounds Ionic compounds are held together in a lattice by attractive forces ( Ionic Bonds ) that exist between positively and negatively charged ions 3.2/3.3 Formula Units of Ionic Compounds The formula unit of an IONIC compound is the smallest whole number ratio possible for cations(+) and anions(–) that gives neutrality
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Chapter 3: Molecules, Compounds, and Chemical Equations 3.2/3.3 Compounds – Molecular or Ionic Ionic compounds tend to form between metals and non-metals - Molecular (Covalent) compounds tend to form between non-metals and non- metals 3.5/3.6 Compounds (Ionic and Molecular) : Formulae and Names Nomenclature is a systematic method for naming compounds and writing formulas for compounds Organic and Inorganic Compounds Organic compounds are composed of the elements C , H, N, O, P, S Organic chemistry is the study of carbon and its compounds Inorganic compounds are composed of all the other lovely stuff, including boron 3.5/3.6 Names and Formulae of Binary Inorganic Compounds Binary compounds contain 2 elements : - A1, A2, A3, Metal + Non-Metals (IONIC) - B. Non-Metal + Non-Metal (MOLECULAR) - C. Non-Metal + Hydrogen A1. Binary Compounds Metal + Non-metal ( IONIC ) Some metals form
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Chapter 3 - Chapter 3: Molecules, Compounds, and Chemical...

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