Molecular Elements

There are many substances that exist as two or more atoms connected together so strongly that they behave as a single particle. These multi-atom combinations are called molecules. The smallest part of a substance that has the physical and chemical properties of that substance. A molecule is the smallest part of a substance that has the physical and chemical properties of that substance. In some respects, a molecule is similar to an atom. A molecule, however, is composed of more than one atom.

Some elements exist naturally as molecules. For example, hydrogen and oxygen exist as two-atom molecules. Other elements also exist naturally as diatomic molecules. A molecule with only two atoms (Table 1 ). As with any molecule, these elements are labeled with a molecular formula, a formal listing of what and how many atoms are in a molecule. (Sometimes only the word formula is used, and its meaning is inferred from the context.) For example, the molecular formula for elemental hydrogen is H₂, with H being the symbol for hydrogen and the subscript 2 implying that there are two atoms of this element in the molecule. Other diatomic elements have similar formulas: O₂, N₂, and so forth. Other elements exist as molecules—for example, sulfur normally exists as an eight-atom molecule, S₈, while phosphorus exists as a four-atom molecule, P₄ (Figure 1).

Figure 1 : Molecular Art of S₈ and P₄ Molecules. If each green ball represents a sulfur atom, then the diagram on the left represents an S₈ molecule. The molecule on the right shows that one form of elemental phosphorus exists, as a four-atom molecule.

Figure 1 shows two examples of how we will be representing molecules in this text. An atom is represented by a small ball or sphere, which generally indicates where the nucleus is in the molecule. A cylindrical line connecting the balls represents the connection between the atoms that make this collection of atoms a molecule. This connection is called a chemical bond.

مواضيع ذات صلة

تسمية المركبات الجزيئية Molecular Compounds

تسمية المركبات الأيونية Ionic Compounds

تسمية المركبات Naming Compounds

صيغ المركبات الأيونية Formula of Ionic Compounds

الصيغ الأولية Empirical Formulas

الصيغ الجزيئية Molecular Formulas

الأيونات Ions

الجزيئات Molecules

الجدول الدوري The Periodic Table

العدد الذري وعدد الكتلة والنظائر Atomic Number, Mass Number and Isotopes

النيوترون The Neutron

البروتون والنواة The Proton and the Nucleus