Water chemical formula oxygen atom

A chemical formula denotes the composition of the substance. A molecular formula shows the exact number of atoms of each element in a molecule. In our discussion of molecules, each example was given with its molecular formula in parentheses. Thus, H2 is the molecular formula for hydrogen. Oi is that for oxygen. O3 is that for ozone, and H2O is that of water. The subscript numeral indicates the number of atoms of an element present. There is no subscript for O in H2O because there is only one atom of oxygen in a molecule of water. The number one is never used as a subscript in a chemical formula. Oxygen (O2) and ozone (O3) are allotropes of oxygen. An allotrope is one of two or more distinct forms of an element. Two of the allotropic forms of the element carbon—diamond and graphite—have dramatically different properties (and prices). 

The types of atoms and the number of each type in each unit (molecule) of a given compound are conveniently expressed by a chemical formula. In a chemical formula the atoms are indicated by the element symbols, and the number of each type of atom is indicated by a subscript, a number that appears to the right of and below the symbol for the element. The formula for water is written H2O, indicating that each molecule of water contains two atoms of hydrogen and one atom of oxygen (the... 

The chemical formula for water shows how formulas are constructed. The formula lists the symbols of all elements found in the compound, in this case H (hydrogen) and O (oxygen). A subscript number after an element s symbol denotes how many atoms of that element are present in the molecule. The subscript 2 in the formula for water indicates that each molecule contains two hydrogen atoms. No subscript is used when only one atom is present, as is the case for the oxygen atom in a water molecule. Atoms are indivisible, so molecules always contain whole numbers of atoms. Consequently, the subscripts in chemical formulas of molecular substances are always integers. We explore chemical formulas in greater detail in Chapter 3. 

The chemical name of compounds composed of only two elements usually ends with the suffix ide. The chemical name for water, for example, which is composed of two atoms of hydrogen and one of oxygen, and whose chemical formula is H20, is, therefore, hydrogen oxide. The chemical name for common table salt, composed of one atom of sodium and one of chlorine, and has the formula is NaCI, is sodium chloride. Pyrite, an iron ore composed of one atom of iron (ferrum in Latin) and one of sulfur, has the formula FeS, and its chemical name is ferrous sulfide. 

A coefficient in front of a chemical formula tells us the number of times that element or compound must be counted. For example, 2 F120 indicates two water molecules, which contain a total of four hydrogen atoms and two oxygen... 

Ethers are organic compounds structurally related to alcohols. The oxygen atom in an ether group, however, is bonded not to a carbon and a hydrogen but rather to two carbons. As we see in Figure 12.14, ethanol and dimethyl ether have the same chemical formula, C2H(50, but their physical properties are vastly different. Whereas ethanol is a liquid at room temperature (boiling point 78°C) and mixes quite well with water, dimethyl ether is a gas at room temperature (boiling point —25°C) and is much less soluble in water. 

Remember that a chemical formula uses chemical symbols and numbers to show the kinds of atoms of each element that are joined together. The chemical formula for water is HaO. This means that two atoms of hydrogen are chemically joined to one atom of oxygen to make a molecule of water. A molecule is the smallest unit of a chemical compound that still has the same chemical properties of the compound. When there is only one atom in a molecule, such as the oxygen in water, the numeral 1 is not written but is just assumed to be there. 

Scientists use chemical formulas as a short way to show the elements that make up a molecule of a substance. A chemical formula includes the symbols of each element that makes up the molecule. The formula for water, for example, is H20. This chemical formula shows that two hydrogen atoms are bonded to one oxygen atom in one molecule of water. 

Most substances consist of two or more elements joined by chemical bonds. For example, consider the chemical combination of the elements hydrogen and oxygen shown in Figure 1.6. Oxygen, chemical symbol O, has an atomic number of 8 and an atomic mass of 16, and it exists in the elemental form as diatomic molecules of 02. Hydrogen atoms combine with oxygen atoms to form molecules in which two H atoms are bonded to one O atom in a substance with a chemical formula of H20 (water). A substance such as H20 that consists of a chemically bonded combination of two or more elements is called a chemical compound. In the chemical formula for water the letters H and O are the chemical symbols of the two elements in the compound and the subscript 2 indicates that there are two H atoms per one O atom. (The absence of a subscript after the O denotes the presence of just one O atom in the molecule.)... 

Atoms are conserved in a chemical reaction so that the number of carbon atoms, oxygen atoms, and hydrogen atoms must be the same on each side of the equation. The formula states that one atom of carbon reacts with one molecule of water to form one molecule of carbon monoxide and one molecule of hydrogen gas. The relative amounts of the substances participating in a reaction are given by the coefficients in the reaction formula, termed stoichiometric coefficients. In this case all the stoichiometric coefficients are one. 

A most familiar molecule is water. H20 is the chemical formula for water and a shorthand way to say that each water molecule is made up of two hydrogen atoms and one oxygen atom as shown in Figure 1.3. In the figure, the lines between hydrogen and oxygen represent bonds. 

The sum of the oxidation numbers in a neutral molecule or compound is zero. Table salt, with the chemical formula of sodium chloride, is made up of two ions, a positively charged sodium ion and a negatively charged chloride ion. A water molecule consists of two hydrogen atoms, each having an oxidation number of plus one, and an oxygen atom with an oxidation number of minus two. 

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