When solid, non-metals tend to be brittle, such as sulfur, which flakes apart rather than bending like a metal would Fig. The elements in Group 17, including fluorine F 2 , chlorine Cl 2 , Fig.
The nonmetals in Group 17 are all diatomic two atoms in their elemental form and have similar reactive properties. There are other organizational features of the periodic table. Most periods have the first element of the period in Group 1 and the last element in Group An exception is the first period. Sometimes hydrogen H is placed in Group 17, above fluorine F , because it has similar properties to the nonmetals in that group; for example, in its elemental state hydrogen exists as a diatomic gas, H2. Sometimes hydrogen is placed in both Groups 1 and Groups of elements have similar properties.
The properties of some groups are so unique or important that the groups are referred to by special names. The elements in this group are called the noble gases. Noble gases seldom react with other elements. Noble gases have many uses, for example, they are used in neon signs Fig 2. Group 1 is often referred to as the alkali metals, Group 2 as the alkaline earth metals, and Group 17 as the halogens. The two groups that are pulled out on the bottom of the periodic table in rows are called the lanthanide rare earth series top row and the actinide series bottom row.
Molecules and Models: The molecular structures of main group element compounds
This document may be freely reproduced and distributed for non-profit educational purposes. Skip to main content. Search form Search. Join The Community Request new password. Main menu About this Site Table of Contents. Atoms, Molecules, and Compounds. NGSS Performance Expectations: HS-PS Use the periodic table as a model to predict the relative properties of elements based on the patterns of electrons in the outermost energy level of atoms.
The content and activity in this topic will work towards building an understanding of the structure of atoms and how elements are organized on the periodic table. Chemical Structures The properties of elements and compounds are determined by their structures. Determine how charged matter interacts. Other Organizational Features of the Periodic Table There are other organizational features of the periodic table. Further Investigations.
Molecules and models : the molecular structures of main group element compounds - Semantic Scholar
Table of Contents: Atoms, Molecules, and Compounds. Activity: Electrostatic Forces.
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Molecules and Models: The Molecular Structures of Main Group Element Compounds
Partner Organizations. Professional Development. Purchase a membership! Atomic Number. Atomic Symbol. Number of Protons. Number of Electrons. Many compounds do not contain ions but instead consist solely of discrete, neutral molecules. These molecular compounds covalent compounds result when atoms share, rather than transfer gain or lose , electrons. Covalent bonding is an important and extensive concept in chemistry, and it will be treated in considerable detail in a later chapter of this text.
We can often identify molecular compounds on the basis of their physical properties. Under normal conditions, molecular compounds often exist as gases, low-boiling liquids, and low-melting solids, although many important exceptions exist. Whereas ionic compounds are usually formed when a metal and a nonmetal combine, covalent compounds are usually formed by a combination of nonmetals.
Thus, the periodic table can help us recognize many of the compounds that are covalent. Predicting the Type of Bonding in Compounds Predict whether the following compounds are ionic or molecular:. Solution a Potassium group 1 is a metal, and iodine group 17 is a nonmetal; KI is predicted to be ionic. Check Your Learning Using the periodic table, predict whether the following compounds are ionic or covalent:. Metals particularly those in groups 1 and 2 tend to lose the number of electrons that would leave them with the same number of electrons as in the preceding noble gas in the periodic table.
By this means, a positively charged ion is formed. Similarly, nonmetals especially those in groups 16 and 17, and, to a lesser extent, those in Group 15 can gain the number of electrons needed to provide atoms with the same number of electrons as in the next noble gas in the periodic table.
Thus, nonmetals tend to form negative ions. Positively charged ions are called cations, and negatively charged ions are called anions. Ions can be either monatomic containing only one atom or polyatomic containing more than one atom. Compounds that contain ions are called ionic compounds. Ionic compounds generally form from metals and nonmetals. Compounds that do not contain ions, but instead consist of atoms bonded tightly together in molecules uncharged groups of atoms that behave as a single unit , are called covalent compounds.
Covalent compounds usually form from two nonmetals. Skip to content Increase Font Size. Chapter 2. Atoms, Molecules, and Ions. Learning Objectives By the end of this section, you will be able to: Define ionic and molecular covalent compounds Predict the type of compound formed from elements based on their location within the periodic table Determine formulas for simple ionic compounds. Example 1 Composition of Ions An ion found in some compounds used as antiperspirants contains 13 protons and 10 electrons.
Example 2 Formation of Ions Magnesium and nitrogen react to form an ionic compound. Figure 4. Although pure aluminum oxide is colorless, trace amounts of iron and titanium give blue sapphire its characteristic color. Answer: Na 2 S. Answer: Li 2 O 2. Example 5 Predicting the Type of Bonding in Compounds Predict whether the following compounds are ionic or molecular: a KI, the compound used as a source of iodine in table salt b H 2 O 2 , the bleach and disinfectant hydrogen peroxide c CHCl 3 , the anesthetic chloroform d Li 2 CO 3 , a source of lithium in antidepressants Solution a Potassium group 1 is a metal, and iodine group 17 is a nonmetal; KI is predicted to be ionic.
For each of the following compounds, state whether it is ionic or covalent. Previous: 2. Next: 2. License 2. Share This Book. Each element is represented by its own chemical symbol.
The periodic table shows the names and symbols of the elements. A chemical symbol:. For example, the element mercury is shown as Hg. You must not show it as HG, hg or hG. A chemical formula represents an element or compound in balanced equations. The formulae for most elements is just their symbol.