Chem 101 1st EditionExam # 2 Study Guide Lectures: 6 - 9Lecture 6 (February 4)Regions of the Periodic TableWhat are the main groups of the periodic table and what column or family do they correspond with? How do you locate an element on the periodic table by using the period and group numbers?The columns are known as Families or Groups (G1-G18)G1: Alkali MetalsG2: Alkaline Earth MetalsG3 – G12: Transition MetalsG13: B GroupG14: C GroupG15: N GroupG16: O GroupG17: Halogens G18: Noble Gases: these elements fulfill the octet rule and there for are stable and un-reactive.The rows are known as Periods. It is important to remember the correlation between periods and the energy level of electron orbitals. You can use the group numbers and periods to locate elements on the periodic table. Think of them as coordinates. Example: Zinc is an element from period 4 and group 12What is a Halogen from period 3?  ClValence electrons (VE) are the electrons in the outer shell of an atom. The valence electrons are the ones involved in forming bonds to adjacent atoms. Therefore, the number of VE is important for determining the number of bonds an atom will form, the number of unpaired electrons, and an atom's formal charge.You can determine the number of valence electrons by looking at the periodic table:As you can see the Alkali metals have only 1 valence electron. These elements are highly reactive. Other than H, these elements want to achieve the octet rule. Octet Rule: is a chemical rule of thumb that states that atoms of main-group elements tend to combine in such a way that each atom has eight electrons in its valence shell, giving it the same electronic configuration as a noble gas (which as stated above, is stable)Not all elements fulfill the octet rule, such as H and He, and other elements can exceed the octet rule. However, you are not responsible for the elemental compounds that exceed the octet rule. Understand that because H and He only have 1- 2 electrons their valence shell is complete at 2 electrons.Types of Compounds IntroCovalent Compounds are formed from the sharing of electrons between nonmetal elements. We will be looking at formulas of binary covalent compounds.Example: CO2, HF, PF5, N2O3  notice that these covalent compounds are composed of nonmetals. That is how you determine what kind of compound you are looking at. Also notice the order in which the elements of the compounds are in. Notice howthe subscripts go from low to high as you move from left to right. This is because generally the element with lower electro negativity. Lecture 7 (February 11)CompoundsDistinguish between covalent (molecular) and ionic compounds. You must be able to correctly name a compound as well as write the correct formula of a compound. You must memorize the prefixes for covalent compounds (figure 4.1) Ionic Compounds are composed of ionic bonds; a type of chemical bond that involves the electrostatic attraction between oppositely charged ions and the transferring of electrons. The ions represent atoms that have lost one or more electrons (known as cations) and atoms that have gained one or more electrons (known as an anion).Ionic compounds tend to have high melting points and form ridged structures. The strength of the attraction between ions is directly related to the magnitude of their charges. These bonds form between metals and nonmetals. You can determine if a compound is ionic if one of the atoms is that of a metal element. Metals lose electrons to nonmetals. Cations are positively charged. Anions are negatively charged.The differences in charges are what form the attractions between the cations and anions. The opposite charges balance each other out. Alkali metals are unstable and quick to lose electrons. Anions always have a fixed charge. To figure out the charge of an anion take the group number of the atom and subtract 18. Cations can either have a fixed charge or a variable charge. Cations with a fixed charge:- Metals from Group 1 gave a charge of +1- Metals from Group 2 gave a charge of +2- Metals from Group 13 have a charge of +3 - Al and Ga from Group 13 also have a fixed charge of +3- Zn has a fixed charge of +2 - Ag +1 ionCations with a variable charge:- Transition metals (with Zn and Ag as exceptions)- Fe: Fe+2, Fe+3- Cu: Cu+, Cu+2- Co: Co+2, Co+3Remember that Formula Units are the empirical formula of any ionic or covalent network solid compound used as an independent entity for Stoichiometry calculations. It is the lowest whole number ratio of ions represented in an ionic compound.Naming Covalent BondsNaming Covalent Bonds: The first element is named first, using the elements name. Second element is named as an Anion (suffix "-ide")Prefixes are used to denote the number ofatoms. You must memorize these. "Mono" is notused to name the first element. Example: Carbon oxide (CO)1. S – sulfide2. O – oxide 3. N – nitride4. Se – Selenide 5. B – boride6. I – iodide7. Cl – Chloride8. F – fluoride 9. As – Arsenide10. P – phosphide Naming Ionic Compounds the cation (positively charged ion) is always named first. The anion is written second in the name. 1. If the cation is a metal ion with a fixed charge, the name of the cation is the sameas the (neutral) element from which it is derived (e.g., Na+ = "sodium").2. If the cation is a metal ion with a variable charge, the charge on the cation is indicated using a Roman numeral, in parentheses, immediately following the name of the cation (e.g., Fe3+ = "iron(III)").a. Fe+3  Iron (III) b. Cu+  Copper (I) c. Co+2  Cobalt (II) 3. If the anion is a monatomic ion, the anion is named by adding the suffix -ide to the root of the element name (e.g., I- = "iodide") \4. Note: Greek prefixes are not used to indicate the number of atoms, or polyatomicions, in the formula unit for the compound (ex, Ca(NO3)2 is named "calcium nitrate" not "calciuim dinitrate").Ex: Na2S – Sodium SulfideA good way to study this concept is to write out and memorize the concept map on page 107 in your chemistry book. It looks something along the lines of this:Lecture 8 (February 23)IonsYou must memorize the polyatomic ions from figure 4.3 in your book; both the formula name and charge. Be able to distinguish between polyatomic and Monoatomic. You must be able to apply your knowledge to write out chemical formulas as well as balance them.Polyatomic ions also known as a molecular ion, is a charged ion composed of two or more atoms