Log in graccebird121 7 years agoPosted 7 years ago. Direct link to graccebird121's post “I'm still a little confus...” I'm still a little confused on how to know what the chemical name is going to end with depending on the number of ions • (41 votes) alex 7 years agoPosted 7 years ago. Direct link to alex's post “At 2:37, this is confusin...” At • (17 votes) RogerP 7 years agoPosted 7 years ago. Direct link to RogerP's post “The overall structure nee...” The overall structure needs to be neutral in terms of charge. Thus Ca has a charge of +2 and Br has a charge of -1. Therefore, to get a neutral compound requires two Br and one Ca - ie, CaBr2. (10 votes) Andrea Balingit 7 years agoPosted 7 years ago. Direct link to Andrea Balingit's post “Why did he not put a pare...” Why did he not put a parenthesis? Ca(Br)2? • (13 votes) awemond 7 years agoPosted 7 years ago. Direct link to awemond's post “Parentheses are generally...” Parentheses are generally only used for complex ions. Since the anion here, Br, is a single atom, there is no need to include parentheses. If the anion had been, for example HSO4-, then we would have included parentheses to make it clear that here are two of these complex anions: Ca(HSO4)2. (17 votes) Matt Broadley 7 years agoPosted 7 years ago. Direct link to Matt Broadley's post “What is the rule for an i...” What is the rule for an ionic compound ending in ate, ite, or ide (or any other suffix)? The way I understand it right now is that "ide" is from when there is two of an anion, "ite" is for three of an anion, and "ate" is for four of an anion. Is this right? • (6 votes) Ryan W 7 years agoPosted 7 years ago. Direct link to Ryan W's post “-ide is just the negative...” -ide is just the negative anion of that element, chloride, sulfide, nitride -ate depends on the central atom, it's generally the most common n eg phosphate is PO4 3-, sulfate is SO4 2- but nitrate is NO3 - and chlorate is ClO3 - -ite is 1 less oxygen than -ate, phosphite is PO3 3-, sulfite is SO3 2-, nitrite is NO2 - Hypo- -ite means 1 oxygen less than -ite eg ClO2- is chlorite and ClO- is hypochlorite Per- -ate means 1 oxygen more than -ate eg ClO3 - is chlorite and ClO4- is perchlorate (28 votes) Matthew Nodar 7 years agoPosted 7 years ago. Direct link to Matthew Nodar's post “How do we know that Bromi...” How do we know that Bromine will gain an electron just based on where it is on the periodic table? • (6 votes) Andrew M 7 years agoPosted 7 years ago. Direct link to Andrew M's post “It wants to fill its oute...” It wants to fill its outer shell, and if it can do that easily by gaining an electron, that's what it will do. (6 votes) Ahmed Mohamed Salah Elkhodary 7 years agoPosted 7 years ago. Direct link to Ahmed Mohamed Salah Elkhodary's post “At 2:32, the ionic compou...” At • (4 votes) Ryan W 7 years agoPosted 7 years ago. Direct link to Ryan W's post “You would need to know wh...” You would need to know what oxidation state the metal is in first. It should always be included in the name. Iron(II) bromide would be FeBr2 while iron(III) bromide would be FeBr3 Copper(I) bromide would be CuBr while copper(II) bromide would be CuBr2 Does that help? (8 votes) courtney a year agoPosted a year ago. Direct link to courtney's post “How do you know which ele...” How do you know which elements are going to be 2+ or 1- and so on? • (4 votes) Richard a year agoPosted a year ago. Direct link to Richard's post “For the most part it depe...” For the most part it depends on the group (column) in which the element is found in on the periodic table. It corresponds to how many valence electrons those elements in that group have and therefore how many they wish to donate to other atoms to form cations. Elements in group 1, the alkali metals, have one valence electrons so they tend to lose that one electron and take on a +1 charge. Elements in group 2, the alkaline earth metals, take on a +2 charge for a similar reason. Elements in group 13 take on a +3 charge. Elements in group 14 have the possibility of taking on a +4 or a -4 charge. And the groups further to the right tend to take on negative charges to become anions because they like to accept electrons now instead of donate them. Collectively these elements in groups 1-2 & 13-18 are known as main block elements and have (usually) constant charges. The elements in the middle of the periodic table, the transition metals, are odd in that they have the potential of taking on several possible positive charges. Hope that helps. (7 votes) C4LOwenZ 10 months agoPosted 10 months ago. Direct link to C4LOwenZ's post “1:27 I'm pretty sure Brom...” • (2 votes) Lady of Light 10 months agoPosted 10 months ago. Direct link to Lady of Light's post “Halides are chemical comp...” Halides are chemical compounds that contain halogens, so this example, CaBr2, is a Halide. Bromine itself is a Halogen. (5 votes) Jean Helen 7 years agoPosted 7 years ago. Direct link to Jean Helen's post “Its still not clear how t...” Its still not clear how there are 2 bromides in the end. Can you please explain? • (1 vote) Ryan W 7 years agoPosted 7 years ago. Direct link to Ryan W's post “Calcium commonly forms a ...” Calcium commonly forms a cation with a charge of +2 In the formula of an ionic compound we are showing the ratio between the ions. The overall charge of any ionic compound is 0 so for that to happen we need 2 bromide ions for every 1 calcium ion. (6 votes) Polly Bochkariov a year agoPosted a year ago. Direct link to Polly Bochkariov's post “There is something I don'...” There is something I don't understand. How can I figure out the formula of an ionic metal compound using the periodic table? How do I know that Iron is going to form a more than one positive ion? My textbook has this example question where it says, "What is the chemical name for the ionic compound CuCl2?" The answer is, of course, copper (II) chloride. But why can't it be Copper (IV) chloride? Or Copper (III) chloride? Do you use electron configurations? Or does this have to do with the charge of the atoms? • (2 votes) Richard a year agoPosted a year ago. Direct link to Richard's post “Ionic compound’s empirica...” Ionic compound’s empirical formulae always have a neutral net charge, or a total charge of 0. The positive charges must equal and cancel all the negative charges. So the cumulative charges of the cations (a metal often) must equal the charges of the anions (a nonmetal often). The elements in the s and p blocks (groups 1,2, & 13-18) are collectively referred to as main group and for the most part have constant charges. Group 1 elements have 1+ charges for example, while group 17 elements have 1- charges. This is a generalization and there are exceptions to this rule; lead for example is a main group element but can take on +2 and +4 charges. Elements in the middle of the periodic table, the transition metals, can take on several different positive charges in different compounds. We differentiate between these possible charges by using roman numerals in their names. So CuCl2, has copper (the cation and a transition metals with variable charges) and chlorine (the anion with a constant 1- charge). We know the whole formula must be neutral to the copper’s positive charge must cancel the negative charges of the two chlorines. We can determine the copper’s charge using algebra: x + 2(-1) = 0, where x is the copper’s charge. Doing some quick math, we find that x = 2, so copper has a 2+ charge. The name should therefore be copper(II) chloride. Copper(III) chloride and copper(IV) chloride would have the formulas CuCl3 and CuCl4 respectively using the same rules. Hope that helps. (3 votes)Want to join the conversation?
2:37
2:32 1:27
Bromine commonly forms an anion with a charge of -1
So the formula is CaBr2
Sorry for a million questions, but I DO need help! Thank you!
Video transcript
- [Instructor] Let's now see if we can come up with the chemical formula for the ionic compound calcium bromide. And like always, if you areinspired, pause the video and see if you can comeup with it on your own. All right, so theconvention is that we write the positive ion first andso that's a pretty good clue that calcium is goingto be the positive ion. Now let's look at theperiodic table to confirm that it's likely that calciumwould ionize as a cation. Well, calcium is rightover here in Group Two, and Group Two elements, alsoknown as alkaline earth metals, they tend to ionize bylosing two electrons and that's because they have two electrons in their outermost shell andthey would like to lose them. And so when calciumionizes, it is going to be, it is going to ionize as Ca2+. Now, let's look at the bromide part. The -ide tells us that thisis going to be a negative ion or it's going to be an anion. And if you look at where brominesits in our periodic table, right over here, we see it is a halide. We see that it likes to gain an electron and so it makes sense thatit's going to be our anion. And so bromine wouldlike to gain an electron to have eight electronsin its outermost shell. So, our bromide anion isgoing to look like this. It's going be to 1-. It's gonna wanna gain an electron, that's what the elementsin this group like to do. Now, what is the formula going to be, and remember, the key hereis for an ionic compound, especially one thathas, well, we don't see any net charge here,for an ionic compound, these things are goingto cancel each other out. The charge of the calcium cation is going to cancel outwith the bromide anion. So how is that going to happen? Well, have you 2+ here,you only have 1- here, so you're gonna have to have two bromides for every of the calcium ions. So this is going to be, forevery one of the calciums, you're going to have two bromides. So it's going to be like this, Br2, and there you have it, that is the chemical formula for calcium bromide. And how did we know that we have two bromides for every calcium? Well, because when calciumionizes, it's going to be 2+, it's a Group Two element right over here. And bromine only gets a -1 or a 1- charge, so you're gonna need two of the bromides for every one of the calciums.
