Chapter 7: Ionic and Metallic Bonding ` Name: Period : Date: California Chemistry Content Standards Atomic and Molecular Structure The periodic table displays the elements in increasing atomic number and shows how periodicity of the physical and chemical properties of the elements relates to atomic structure. As a basis for understanding this concept: e. Students know how to use the periodic table to determine the number of electrons available for bonding. Chemical Bonds Biological, chemical, and physical properties of matter result from the ability of atoms to form bonds from electrostatic forces between electrons and protons and between atoms and molecules. As a basis for understanding this concept: a. Students know atoms combine to form molecules by sharing electrons to form covalent or metallic bonds or by exchanging electrons to form ionic bonds. b. Students know chemical bonds between atoms in molecules such as H 2, CH 4, NH 3, H 2 CCH 2, N 2, Cl 2, and many large biological molecules are covalent. c. Students know salt crystals, such as NaCl, are repeating patterns of positive and negative ions held together by electrostatic attraction. d. Students know how to draw Lewis dot structures. 7.1 Ions I. Valence Electrons- A. For representative elements, the number of valence electrons is equal to. B. Valence electrons determine the of the element. Examples: Give the number of valence electrons for the following elements. Na = Al = Cl = C. Electron dot structures 1
II. The Octet Rule - A. Octet rule explains why some elements lose electrons, and some gain electrons. B. Metals tend to their valence electrons, leaving a complete octet in the nextlowest energy level. C. The ion formed will be ( ). D. For metal ions: Charges of cations: Group 1A = Group 2A = Group 3A = E. Atoms of some non-metals tend to electrons or to share electrons with another nonmetal to achieve a complete octet. F. The ion formed will be ( ). G. For nonmetal ions: H. Charges of anions: Group VI1A = Group VIA =.Group VA = Examples: Give the symbols for the ions formed by the following elements. Br: K: N: Al: S: Cs: Formation of Cations A. Cations formed by some elements in groups 1A, 2A and 3A: B. The name of the ion Examples: Cs: Ca: Al: Mg: 2
Formation of Anions A. Anions formed by some elements in groups 5 6A and 7A: B. The name of the anion: Examples: N Br: S: P: C. All halogens electron and are called Polyatomic Ions A group of atoms carrying a charge Examples: Write the symbol and name of the ion formed when a) Iodine gains one electron b) Strontium loses 2 electrons. c) Sulfur gains 2 electrons d) Aluminum loses three electrons 3
7.2 Ionic Bonds and Ionic Compounds I. Formation of Ionic Compounds A. Ionic Compounds B. Although they are composed of ions, ionic compounds are neutral. C. Ionic Bonds D. Chemical formula - 1. Since an ionic compound is a very large array of anions and cations, the chemical formula does not represent a, but a. 2. Formula unit - Examples: 1. What is the chemical formula of sodium chloride? 2. What is the chemical formula of magnesium chloride? 3. What is the formula of the compound between potassium and oxygen 4. What is the formula of the compound between magnesium and nitrogen? 5. Write the formula of the compound between potassium and iodine 6. Write the formula of the compound between aluminum and oxygen. 4
III. Properties of Ionic Compounds 7.3 Bonding in Metals 1. Most ionic compounds are crystalline at room temperature. 2. Ionic compounds generally have melting points. 3. The orderly arrangement of component ions produces solids. 4. Ionic compounds can conduct an when melted or dissolved in water. I. Metallic Bonds and Metallic Properties II. Alloys A. The valence electrons of metal atoms can be modeled as a. 1. The valence electrons are mobile and can drift freely from one part of the metal to another. 2. Metallic bonds consist of the attraction of the free-floating valence electrons for the positively charged metal ions. 1. Alloys are important because their properties are often superior to those of their component elements. 2. Bicycle frames are often made of titanium alloys that contain aluminum and vanadium. 3. The most important alloys today are steels. Steels have a wide range of useful properties, such as corrosion resistance, ductility, hardness, and toughness. 5
Check Your Understanding 1. How many valence electrons are there in an atom of oxygen? a) 2 b) 4 c) 6 d) 8 2. Atoms that tend to gain a noble gas configuration by losing valence electrons are a) metals. b) nonmetals. c) noble gases. d) representative elements. 3. When a magnesium atom forms a cation, it does so by a) losing two electrons. b) gaining two electrons. c) losing one electron. d) gaining one electron. 4. When a bromine atom forms an anion, it does so by a) losing two electrons. b) gaining two electrons. c) losing one electron. d) gaining one electron 5. Which chemical formula is incorrect? a) KF 2 b) CaS c) MgO d) NaBr 6. Ionic compounds can conduct an electric current a) only when melted. b) when melted or dissolved in water. c) only when dissolved in water. d) when solid or melted. 7. At room temperature, most ionic compounds are a) crystalline solids. b) liquids. c) gases. d) soft, low melting-point solids. 8. The valence electrons of metals can be modeled as a) a body-centered cube. b) octets of electrons. c) a rigid array of electrons. d) a sea of electrons. 9. In most metals, the atoms are a) free to move from one part of the metal to another. b) arranged in a compact and orderly pattern. c) placed at irregular locations. d) randomly distributed. 10. Alloys are important because they a) are pure substances. b) are the ores from which metals can be refined. c) can have properties superior to those of their components. d) are produced by the combustion of metals. 6