The Components of Matter

Taking It Apart Like this machine transmission, every day matter consists of simpier components that are themselves made of even simpler parts. In this chapter, you ll learn their properties and discover how chemists identify the components to see how they combine. 

A substance is matter with a fixed composition an element consists of a single type of atom a compouncf consists of molecules (or formula units) made up of two or more atoms combined in a specific ratio. A mixture consists of two or more substances intermingled physically and, thus, has a variable composition. 

According to Dalton s atomic theory, atoms of a given element have a unique mass and other properties. Mass is conserved during a chemical reaction because all the atoms of the reacting substances are just rearranged into different substances. 

Atoms have a structure made of three types of subatomic particles positively charged protons and uncharged neutrons make up the nucleus, which contains nearly all the mass of the atom negatively charged electrons move continuously around the nucleus. All the atoms of a given element have the same number of protons atomic number, Z). Atoms are neutral because the number of protons equals the number of electrons. 

Isotopes of an element are atoms of different masses because they have different numbers of neutrons, but they behave the same way chemically. The atomic mass of an element is the weighted average of the masses of its naturally occurring isotopes. 

The electrons of atoms are involved in forming compounds. In ionic bonding, metal atoms transfer electrons to nonmetal atoms, and the resulting charged particles (jons) attract each other into solid arrays. In covalent bonding, nonmetal atoms share electrons and usually form individual molecules. Each compound has a unique name, formula, and mass based on its component elements. 

Unlike compounds, mixtures can be separated by physica/mearTS into their components. A heterogeneous mixture has a non-uniform composition with visible boundaries between the components. A homogeneous mixture (solution) has a uniform compositton because the components (elements and/or compounds) are mixed as individual atoms, ions, or molecules. 

Atomic Number, Mass Number, and Atomic Symbol 

Formation of Ionic Compounds Formation of Covalent Compounds 

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What was the basic philosophy of Aristotle on the components of matter ... 

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