Classification of Chemical Substances
Experiment #17
Classification of Chemical Substances
Prepared for: Dr. Robert O’Reilly
By: Kudaibergenov Baizak
20.11.2013
Nazarbayev University
Introduction
While many thousands of substances are known, they can be classified into a few simple categories based on type of bonding that exists among the atoms in the substance. Bonds are chemical forces that hold atoms together to form molecules or compounds. These categories are ionic, molecular and metallic substances.
In ionic compounds valence electrons are transferred from one atom to another, resulting in formation of ions of opposite charge. Metals will lose electrons to form cations (positively charged) and non-metals can gain electrons to form anions (negatively charged); these oppositely charged ions attract each other and form an ionic compound Because the attraction of the ions is so strong, ionic compounds are always solid at room temperature and usually crystalline with high melting and boiling points. They usually are soluble in water and form solutions that will conduct electricity because free ions are formed in solution. They will also conduct electricity when melted and are usually insoluble in organic liquids.
In molecular compounds, the atoms share valence electrons and are said to be joined by covalent bonds. Molecular compounds can be gases, liquids or low-melting, boiling points and densities than ionic compounds and many are insoluble in water but soluble in organic liquids. They do not conduct electricity when melted or dissolved.
Metallic bonding is a special type of bonding found in samples of pure metals or alloys (mixtures of metals). In a metal the nucleus and core electrons (i.e cations) are surrounded by a “sea” of valence electrons. Since the valence electrons are free to roam over the entire sample (they are described as delocalized), metals are good conductors of electricity in the solid state. Metals are typically lustrous (shiny), flexible, malleable
Classification of Chemical Substances
Prepared for: Dr. Robert O’Reilly
By: Kudaibergenov Baizak
20.11.2013
Nazarbayev University
Introduction
While many thousands of substances are known, they can be classified into a few simple categories based on type of bonding that exists among the atoms in the substance. Bonds are chemical forces that hold atoms together to form molecules or compounds. These categories are ionic, molecular and metallic substances.
In ionic compounds valence electrons are transferred from one atom to another, resulting in formation of ions of opposite charge. Metals will lose electrons to form cations (positively charged) and non-metals can gain electrons to form anions (negatively charged); these oppositely charged ions attract each other and form an ionic compound Because the attraction of the ions is so strong, ionic compounds are always solid at room temperature and usually crystalline with high melting and boiling points. They usually are soluble in water and form solutions that will conduct electricity because free ions are formed in solution. They will also conduct electricity when melted and are usually insoluble in organic liquids.
In molecular compounds, the atoms share valence electrons and are said to be joined by covalent bonds. Molecular compounds can be gases, liquids or low-melting, boiling points and densities than ionic compounds and many are insoluble in water but soluble in organic liquids. They do not conduct electricity when melted or dissolved.
Metallic bonding is a special type of bonding found in samples of pure metals or alloys (mixtures of metals). In a metal the nucleus and core electrons (i.e cations) are surrounded by a “sea” of valence electrons. Since the valence electrons are free to roam over the entire sample (they are described as delocalized), metals are good conductors of electricity in the solid state. Metals are typically lustrous (shiny), flexible, malleable