Chapter 7 Section 1

1. Chapter 7 Section 1 Notes

2. Types of Chemical Bonding(via electrostatic attraction) *Chemical bonding= electrostatic attraction that holds two or more atoms togetherbnbnbnbnbnbnbnbnbnbnbnbnbnbnbn 1) Metallic bonding a) holds together metal atoms b) forms by moving electrons in the sea of electrons 2) Ionic bonding • forms between metal and nonmetal atoms • forms by transferring electrons from metal to nonmetal atoms 3) Covalent bonding (or molecular bonding) a) forms between nonmetal atoms b) forms by sharing electrons

3. Ions? 1. form when an atom gains or loses one or more electrons 2. cations a) metal atoms become by losing valence electrons ** valence electrons = the electrons in the highest energy level b) each electron lost = 1+ c) the charge written as a positive number upper right of the atomic symbol (Ex) Ca → 2e- + Ca2+ 3. anions a) nonmetal atoms become by gaining electrons b) each electron gained = 1‒ c) the charge written as a negative number (Ex) P + 3e-→P3-

4. Predicting Valence Electrons • *Why gain or lose electrons? • To achieve 8 valence electrons (called “octet rule”) and become pseudo noble gas • *Why filling up the s and p orbitals? • To lower potential energy and to become stable

5. Practices Draw the (Lewis) dot structure for each atom. • Ca (2) K (3) Ar (4) Al (5) Br (6) C (7) He (8) O (9) P (10) H

6. Naming Ions • Cations • “A” group metals: Name the same as element’s name plus ion (Ex) Ca2+ = calcium ion B) “B” group metals: Name the same as element’s name, charge expressed as a Roman numeral in parenthesis plus ion (Ex) Cu+ = copper(I) ion (Ex) Zn2+ = zinc(II) ion ** Roman numerals: I, II, III, IV, V, VI, VII, VIII, IX, X

7. 2) Anions: Modify the end of nonmetal element’s name with “ide” ending ** Don’t confuse with “ite” or “ate” ending (will learn later) (Ex) hydrogen → hydride oxygen → oxide nitrogen → nitride bromine → bromide phosphorus →phosphide selenium → selenide iodine → iodide sulfur → sulfide halogen → halide

8. Ionic Bond Formation • Cations(+) and anions(‒) attract each other by electrostatic force • # of electrons given = # of electrons accepted • Total positive charge = Total negative charge • Total charge = 0 (or neutral) (Ex) Form the ionic bond between: • Na & Cl • Ca & Br • Al & S

9. Ionic Compounds • Substances formed by ionic bonds • Formula unit: • the smallest building block of an ionic compound • the lowest numbers of cations to anions (Ex) How many Ca2+ ion and F- ions in one formula unit of CaF2?

10. Chemical Formulas • Represent compounds ** Compounds: pure substances formed by either ionic or covalent bonding • Ionic compound formulas • Cation (metal) is written first; then anion (nonmetal) • A subscript is used to indicate the number of ions • The net charge of all ions in an ionic compound = 0 (Ex) What is the chemical formula for combining 2 Al3+ ions with 3 O2- ions?

11. Practices Write the correct chemical formula. • Rb1+ and P3- • Be2+ and Br- • Ti2+ and O2- • strontium chloride • aluminum fluoride • calcium sulfide

12. Properties of Ionic Compounds • Crystalline solid at room temperature • Ions are arranged in repeating 3 dimensional pattern = lattice structure **lattice = rectangular or square structure like windows or doors • High melting point due to strong electrostatic attraction • Conduct electricity in solutions or molten liquid, but not in solid, of ionic compounds