Fix the mistake: Substances Around Us

Classification and Properties of Substances

There are various substances around us. As the starting point of middle-school chemistry, we will learn how to classify substances according to their properties.

Basic Knowledge

Substances are first divided into organic substances and inorganic substances. Organic substances contain carbon and produce carbon dioxide and water when burned (such as sugar, starch, and plastics). Inorganic substances are all other substances, including table salt, metals, and glass. However, carbon, carbon dioxide, and carbonates contain carbon but are conventionally classified as inorganic substances.
Metals have properties in common: ①metallic luster, ②good conduction of electricity and heat, and ③malleability when hammered and ductility when pulled. Only some metals, such as iron, nickel, and cobalt, are attracted to magnets; this is not a property of all metals.

Important Terms
Organic substance（a substance containing carbon that produces carbon dioxide and water when burned）
Inorganic substance（a substance other than an organic substance, such as table salt, metals, and water）
Metallic luster（the shiny brilliance characteristic of metals）
Malleability（the property of spreading into a thin sheet when hammered）
Ductility（the property of stretching into a thin wire when pulled）
Nonmetal（a substance without the properties of metals, such as plastic, wood, and glass）

Further Exploration (Background and Significance)

The idea that substances can be broadly classified using the simple test of whether they produce carbon dioxide when burned is an excellent starting point in chemistry. This test determines whether a substance contains carbon atoms and also serves as an introduction to organic chemistry, which we will study later.
The malleability and ductility of metals result from atoms arranged regularly and held together by free electrons. This is a property of metallic bonding, which is studied in high school. Aluminum cans and copper wires that we use every day take advantage of these properties of metals.

Key Points
  • Organic substances contain carbon and produce CO2 and water when burned
  • Exceptions: carbon, carbon dioxide, and carbonates are classified as inorganic substances
  • Common properties of metals = luster, electrical/thermal conductivity, malleability, and ductility
  • Only some metals (iron, nickel, and cobalt) are attracted to magnets
  • Nonmetals = substances other than metals
  • Metals conduct electricity because of free electrons

Points to Note (Easily Confused)

① Be careful about the boundary between organic substances and inorganic substances. Remember the exceptions—carbon, CO2, and carbonates—which contain carbon but are treated as inorganic substances. ② Metallic luster is common to all metals, but only some metals are attracted to magnets. ③ Distinguish malleability (spreading) from ductility (stretching). ④ Plastic is derived from petroleum and is an organic substance (it produces CO2 and water when burned).

Practice

  1. Briefly explain the definition of an organic substance.
  2. List three properties common to metals.
  3. Is plastic an organic or inorganic substance? Answer with a reason.

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