Horizontal rows on the periodic table are called periods Vertical columns are called groups For most of this class we will be more concerned with elements in the same group because they exhibit similar characteristics For example all of the elements in the first group starting with lithium and ending with francium are highly reactive when added to water We will learn more about these trends later in the course For now we are going to focus on a few special groups and focus on their oxidation states or charges when they form ionic compounds Find Group 1 This is the orange column on the far left of the periodic table These elements are called the alkali metals and have an oxidation state of 1 Keep in mind that hydrogen H is actually a nonmental and its location is purely for organization and convenience Find Group 2 This is the yellow column on the left side of the periodic table These elements are called alkaline earth metals and have an oxidation state of 2 Find Group 13 This is the green teal column towards that right side of the periodic table and starts with boron These elements tend have an oxidation state of 3 Keep in mind that boron is a metalloid an element that exhibits both metallic and non metallic properties and will usually form covalent compounds We will talk about this more later Next locate Group 18 This is the light blue column on the far right of the period table These elements are called the Noble Gases and have an oxidation state of 0 These elements do not typically bond with others but some exceptions do exist which we will discuss later in the course Metal element nonmetal element Next is Group 17 This is the light teal color towards the right side of the periodic table These elements are called the halogens and have an oxidation state of 1 Next is group 16 This is the oxygen group located towards the right of the periodic table These elements tend to have an oxidation state of 2 And lastly Group 15 This is the nitrogen group again located towards the right side of the periodic table These elements tend to have an oxidation state of 3 All of the information we just went over will be extremely helpful in teaching you how to read and write formulas for ionic compounds Let s start with the simplest of examples Metals are towards the left of the periodic table and nonmetals are towards the right Example 1 Sodium chloride The first step is to find these elements on the periodic table to get their symbols Sodium Chlorine Now that we have identified the elements we need to apply the information we went over above What are the oxidation state of Na and Cl Na is in Group 1 so its charge is 1 Chlorine is in Group 17 so its charge is 1 Now we can write the ionic symbols for these elements Now we can write the formula for sodium chloride by crossing the charges of each element and making them subscripts for each element in the formula Since the charges were equal and opposite we do not need to write them The 1 and 1 balance each other out and are implied in the formula So we just write NaCl Name of metal root of nonmetal ide How would you go the other way How would you write the name of a compound given the formula Example 2 Our goal is to name this The first thing to do is recognize that this is an ionic compound We know it is because it s the combination of a metal K and a nonmetal S Next we need to decide what kind of ionic compound it is We only know of one type so far which is metal element nonmetal element When this happens we name based on the following pattern So for this example we have Let s look at another form of ionic naming which involves the transition metals The transition metals are the block of elements that fill in Groups 3 12 When writing the formulas of ionic compounds that include transition metals we must be given the charge in the compound s name This is noted by Roman numerals in parentheses after the name of the metal Example 3 Iron III oxide First let s determine the symbols for each element Iron Oxygen Next let s determine the charge for each ion In the case of iron the name iron III told us that the charge of ion was 3 Then for oxygen we just have to use what we learned at the beginning and that is that the oxygen group is 2 So we can write the following Iron Oxygen Next we will do an example of writing the name of a transition metal ionic compound given its formula Example 4 This example is a little more difficult but it serves to show you that you can always find the charge of an atom within a compound if you us the information given above Since titanium is the transition metal we have to figure out its charge To do that we look at what it is combined with In this case we have two oxygens We know what each oxygen will carry a 2 charge We also know that we will only have one titanium So we must ask ourselves what charge must one atom have in order to balance out two atoms each with a 2 charge To balance we must have a 4 charge on the titanium This is shown mathematically Now we can write the name of this When we have a transition metal element and a nonmetal element compound the following pattern is used So for this example we have If we were to write this name into a formula some students might write Ti2O4 This is right except that when we write the formulas of ionic compounds we always want to write empirical formulas or the reduced versions This is why it was written the way it is above Name of transition metal charge in Roman numerals root of nonmetal ide We will now introduce a new component of ionic nomenclature and that is compounds containing polyatomic ions The polyatomic ions that you will need to have memorized for this class include Ammonium Carbonate Chlorate Chromate Cyanide Dichromate Hydroxide Nitrate Permanganate Phosphate Sulfate Thiocyanate Acetate Phosphate Let s practice Example 5 Write the formula for magnesium phosphate The first step is to recognize that this is an ionic compound example We know it is because we can see a metal magnesium and a nonmetal anion phosphate Then we need to determine the formulas for each component Magnesium comes from the periodic table and we know it carries a 2 charge Phosphate comes from the list of polyatomics that we have to have memorized Applying our procedure for ionic compounds Magnesium This is almost right However we need a way to distinguish between 2 phosphate ions in the compound versus having 42 oxygen atoms in the compound For this …
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