Transition Metals Properties

Hey guys. In this new video we're going to take a look at how do we calculate the oxidation number of certain transition metals based on what they're connected to. So, we take a look at this first example, it says, determine the oxidation number of the underlined element. So, we're looking for the oxidation state of nickel. Now here this a little bit different from what we're used to seeing, here we actually have nickel connected to six waters inside of brackets and then chlorines to the right of it. Now, remember since we're looking for nickel here, nickel will be x, then we have to ask ourselves what's the oxidation number of water. Now, just think of it in simple terms, water is a covalent compound and it has no charge, therefore it's oxidation number will be equal to 0, next, we have halogens here, we have chlorine. Now, remember chlorine here is connected to the nickel not to the oxygen and water and remember the rules that we've talked about in the past, group 7a elements, halogens, they're equal to negative one unless they're connected to oxygen, here they're not connected to the oxygen, they're basically closely related to the nickel therefore their oxidation number here is minus one, then we're going to use a, treated like a math problem, we're going to say here we have one nickel, which is x plus six waters, each one is 0, plus two chlorine could little to their, each one is minus one. Remember, our equation equals the charge of the molecule, here it has no charge, there's no positive charge or negative charge that we can see. So, its charge is 0, this drops out because it's just 0. So, x minus 2 equals 0, x equals plus two. So, nickel here would be plus two in terms of its charge, we've done this example here, I want you guys to attempt to you to the next one, see if you can figure out what it would be. Remember, tell yourself, this is a covalent compound, does it have a charge or not, that determines its oxidation state, from there treat it like a math problem, here we're looking for Cobalt, I want you guys to attempt to do this on your own, come back and see how I approach the question.

Hopefully you guys attempted to do on your own. Now, let's take a look at it together, here we have cobalt, which is x again, and here we have ammonia NH3 and we have water again? Well, we know water is 0? Well, remember ammonia is NH3, NH3 is neutral. So, it's oxidation number is 0, if I had given you ammonium ion, ammonium since it's 1+, its oxidation number would have been 1+ just remember, this is ammonia and this here is ammonium, okay? So, remember the difference. So, this would also be 0, these halogens here, each would be 1- treat it like a math problem x1 cobalt plus 4 ammonia each one is 0, plus 1 water, which is 0, plus 1 bromine, which is 1-, plus 2 more bromines, each one is 1- equals a charge of 0. So, here this dropped out, this drops out x minus 2 minus one minus 2 equals 0, x minus 3 equals 0. So, here x equals plus 3. So, that'd be the oxidation state of cobalt. Now, for this practice 1, I want you guys to try to remember what is going on in terms of this question, it's asking us which one has greater metallic behavior, okay? And remember I kind of talked about this when we talked about oxidation states. Remember, the small the oxidation state, what does that mean in terms of the types of bonds we form and the greater the oxidation state of the transition metal, what kind of bonds do we form, this is key to answering this question, attempt to do it on your own and then come back and see how I approach the same question, good luck guys.