## Tips on how to write a formula out from the name

NicoJones_1B
Posts: 49
Joined: Fri Aug 09, 2019 12:16 am

### Tips on how to write a formula out from the name

When there is a word problem that names a chemical compound and it tells you to write the formula what are some tips on how to write out the exact formula. I haven't taken chem since sophomore year of high school so I am not well versed in the names of common chemical compounds, so if you guys know any resources on how I can learn about common chemicals that we will be expected to know in this course please let me know!

Sam McNeill 1E
Posts: 89
Joined: Sat Aug 24, 2019 12:17 am

### Re: Tips on how to write a formula out from the name

There is something called the Hill System Order that states that Carbon is always listed first in the formula, Hydrogen second, and after that all elements are listed in alphabetical order.

Ananta3G
Posts: 62
Joined: Wed Sep 18, 2019 12:19 am

### Re: Tips on how to write a formula out from the name

Hello! I am in a similar boat as you are & I found that the D section in the Fundamentals in the textbook was a really helpful read for brushing up on naming so definitely look into those pages & maybe do some of the exercises there.

Some other tips to remember:

Ionic compounds are named by both their cation & anion with the "ide" ending.

Molecular compounds use a similar rule apart from the fact that you must add the prefix for how many of a given element you have ie SO2 is sulfur dioxide.

Hope these suggestions help!

AChoudhry_1L
Posts: 55
Joined: Sat Sep 07, 2019 12:17 am

### Re: Tips on how to write a formula out from the name

One thing that helps me to write down the formulas from the word is to analyze the prefixes of the words. For example, dioxide means 2 atoms of oxygen because di means 2 and hexafluoride has 6 atoms of fluorine because the prefix hexa means 6. This helps with figuring out what subscript each element will have when writing out the formula.

Jamie Lee 1F
Posts: 81
Joined: Fri Aug 09, 2019 12:16 am

### Re: Tips on how to write a formula out from the name

Khan Academy has always been a great resource to use! https://www.khanacademy.org/science/che ... -compounds

Cations (metals) are named first, then anions (nonmetals). Once you write the atoms down and don't have the charges yet, use the cross over method by writing their charges at the top right (ex: Mg^+2 Cl^-1) and then cross the charges and bring them down to the bottom (ex: MgCl2).

I hope this makes sense!

Anisha Chandra 1K
Posts: 98
Joined: Thu Jul 11, 2019 12:17 am

### Re: Tips on how to write a formula out from the name

I think looking up some common ions in chemistry could be helpful! My junior year chemistry teacher had us memorize some, and based on the suffixes, you can basically start predicting formulas from names after awhile. For example, one set to know would be nitride, nitrite, and nitrate. Another would be sulfide, sulfite, sulfate, etc.

ALegala_2I
Posts: 81
Joined: Thu Jul 11, 2019 12:17 am

### Re: Tips on how to write a formula out from the name

There are several polyatomic ions which are good to memorize. There is a list of nomenclature in the beginning of the book which can be useful for future problems.

MAC 4G
Posts: 97
Joined: Wed Sep 18, 2019 12:16 am

### Re: Tips on how to write a formula out from the name

Also, if you are concerned about this for a test or an exam, my TA said that they normally provide you the formula of the named compound. The only time that they won't is when the question is asking you to write the formula, whether it be the empirical or the molecular formula.

505306205
Posts: 75
Joined: Thu Jul 25, 2019 12:15 am

### Re: Tips on how to write a formula out from the name

There's a list of strong acids and bases in the textbook which would come in handy for some of the problems, so I suggest memorizing them. Learning these would also help with understanding the nomenclature pattern of acids/bases and the ions involved.

Maya Beal Dis 1D
Posts: 82
Joined: Sat Aug 17, 2019 12:16 am
Been upvoted: 2 times

### Re: Tips on how to write a formula out from the name

Do we need to have the formulas and charges of polyatomic ions and their charges memorized or will they be given on a test? For example in textbook problem G.5 you are unable to solve the problem unless you know the molecular formula of sodium carbonate. Will there be problems like this on the test?